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Benign anal and perianal polypoid neoplasms and tumor-like lesions
Pathology – Research and Practice 208 (2012) 719–725
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Original article
Benign anal and perianal polypoid neoplasms and tumor-like lesions Badr AbdullGaffar a,∗ , Tasnim Keloth b , Mouza Al-Hattawi c , Mamoun Al Marzouqi d , Yousif ElTayeb e a
Pathology Section, Rashid Hospital, Oud Metha Road, Dubai, United Arab Emirates Histopathology Department, Dubai Hospital, United Arab Emirates c General Surgery Unit, Dubai Hospital, United Arab Emirates d Pediatric Surgery Unit, AlWasl Hospital, United Arab Emirates e General Surgery Unit, Rashid Hospital, Dubai, United Arab Emirates b
a r t i c l e
i n f o
Article history: Received 18 June 2012 Received in revised form 28 August 2012 Accepted 13 September 2012 Keywords: Anal canal Perianal Polyps Mesenchymal neoplasms Cysts
a b s t r a c t Mesenchymal anal and perianal tumors are relatively uncommon. The majority are malignant. Benign mesenchymal anal tumors are rare. Some are common stromal neoplasms, but with the rare presentation as anal polyps. Other lesions are rare, but unique to the anal/perianal region. Common keratinous cysts might uncommonly present as anal polyps, while other rare cysts are unique to the anogenital region. A retrospective review study of 493 anal and perianal specimens conducted over seven years showed twenty cases (4.0%) of benign anal polypoid lesions. We excluded the usual fibroepithelial polyps, anal tags, papilla, hemorrhoids and warts. We found six cysts, three lipomas, two papillary hidradenomas, two melanocytic nevi, one hamartoma, one xanthogranuloma, one seborrheic keratosis, one hematoma, one fibrous histiocytoma, one granular cell tumor and one lymphangioma. The male to female ratio was 1.5:1. They were found in adults (mean age 37.8 years) and in infants (mean age 2.4 years). In general, they were smaller than 2 cm. They were either asymptomatic or presented with anal pain, bleeding or lumps. Some were clinically confused with the more common non-neoplastic anal tags, hemorrhoids and fibroepithelial polyps/papilla. A variety of common and rare benign lesions might present as anal polyps with important surgical and pathologic challenges and implications. © 2012 Elsevier GmbH. All rights reserved.
Introduction Mesenchymal tumors of the anal canal and perianal region are relatively rare. The majority are malignant [12,13]. Benign mesenchymal tumors are even rarer clinical and pathologic findings [9,27]. Non-epithelial non-mesenchymal neoplasms and tumorlike lesions of the anal/perianal region are also uncommon findings. Both encompass a variety of neoplastic and nonneoplastic mesenchymal and non-mesenchymal lesions. Some, for example, leiomyomas, granular cell tumors and lipomas, are common neoplasms, but with the rare presentation as anal polyps [1,15,17]. Others, for example, papillary hidradenomas, are unique to the perianal region [7]. These lesions can be confused clinically with the common non-neoplastic causes of anal polyps, for example, anal tags, hemorrhoids and fibroepithelial polyps [8]. This might result in inappropriate management of these neoplasms with the risk of local recurrence. Some might present diagnostic challenges to the novice pathologists. Common epidermoid cysts might unusually present as anal polyps, while other rare developmental cysts are
∗ Corresponding author. Tel.: +971 4 219 2948; fax: +971 4 344 6972. E-mail addresses: [email protected], [email protected] (B. AbdullGaffar). 0344-0338/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.prp.2012.09.004
restricted to the perianal region [4,16,20,21]. We aimed to review the prevalence, distribution and the clinical and pathologic importance of benign anal polypoid neoplasms and tumor-like lesions. In our institution, a retrospective review study confirmed the relative rarity of these benign polypoid lesions of the anal canal and the perianal region with an estimated prevalence of 4.0%. It also highlighted the relatively wide spectrum of lesions that could involve the anal and perianal regions. Even though some of these lesions were benign nonneoplastic lesions, most were clinically important for the subsequent management of patients because they were neoplasms with the potential risk of local recurrence. In addition, some may present diagnostic challenges to the unwary pathologists. Materials and methods A retrospective review study of 387 anal specimens and 106 perianal specimens was conducted over seven years from May 2005 to May 2012. Anal and perianal specimens that were removed for symptomatic anal lesions, as well as those removed as part of lower abdominoperineal resection, those that were incidental findings during routine colonoscopy or pediatric examination for suspected Hirschsprung disease, or incidentally discovered by patients or by their mothers, were collected and reviewed. A computer retrieval
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search was used to collect anal specimens that were clinically and grossly labeled as polyps, polypoid, nodule, swelling, mass, papule or wart. The inclusion criteria were lesions arising from the anal canal from the anal verge to 2 cm above the dentate line, as well as from the perianal skin of the anal margin, but the perineum skin was excluded. Lesions from the rectum proper were excluded. Malignant epithelial neoplasms, malignant melanocytic neoplasms and malignant mesenchymal tumors were excluded. The usual anal tags associated with anal fissures, fibroepithelial polyps, and hypertrophic papilla and inflammatory cloacogenic polyps were excluded, as well as hemorrhoids and viral warts. Anal or perianal inflammatory mass lesions secondary to abscess formation, fissures and fistulas were also excluded from the study. Polypoid anal lesions due to secondary metastases of known primary carcinomas or due to extension from rectum, prostate or female reproductive tract, as well as due to lymphomas and leukemias, were excluded. For each collected case, the gross appearance of cut-surface of the specimen, including the size, was recorded. Sections of 4–6 m thickness were stained with routine hematoxylin and eosin (H&E) stain. Serial sections with multiple deeper levels for each block were performed if necessary. All the H&E slides for each collected case were reviewed. Special stains, for example periodic acid Schiff (PAS), Alcian blue, Masson trichrome, and immunohistochemistry (IHC) study for vimentin, smooth muscle actin (SMA), desmin, S100, CD68, CD117, CD34, ALK, HMB45 and cytokeratin (CK) were performed as directed by the H&E slides examination and as appropriate for the diagnosis of certain cases. The age, gender, the clinical data regarding the presentation of the anal polypoid lesions, including the pre-operative clinical impression, as well as follow up data (when available) and any associated lesions, whether local or systemic, were collected. The topographical localization of each lesion in relation to the different zones of the anal canal was recorded.
Results Of the total 493 anal and perianal specimens, twenty cases (4.0%) showed different types of anal and perianal polypoid neoplasms and tumor-like lesions. We found seven anal cases out of 387 anal specimens and thirteen perianal cases out of 106 perianal specimens. The age range was between 1.6 and 56 years with a mean age of 32.5 years. Three cases were in infants with an average age of 2.4 years. The remaining seventeen cases were found in young and middle-aged adults with an average age of 37.8 years. We did not find similar cases between the age 3 and 20, even though 18 patients within this age range had the usual anal/perianal lesions, for example fibroepithelial polyps, warts, papilla, anal tags, fissures and fistulas. In addition, we found ten infants, apart from our three cases, below the age of 3 with the usual anal polyps. The male to female ratio was 1.2–1 (12 males to 8 females). For the total 493 specimens, the male to female ratio was 2.3–1 (345 males to 148 females). Ten cases presented as asymptomatic polyps or lumps, and ten presented with pain, discomfort, tenderness, bleeding and discharge (Table 1). The duration of the presentation ranged from days to weeks to months in most cases and only few for years depending on the symptoms. Clinically, most were diagnosed as anal tags or the usual anal polyps, while others were labeled as hemorrhoids or abscess. Most of the cysts were correctly labeled as cysts. None of the twenty collected cases were found in the specimens retrieved from abdominoperineal resections, during routine colonoscopy, or during pediatric examination for suspected Hirschsprung disease. They were either clinically symptomatic, presented as palpable polypoid lumps or were incidentally discovered by the parents. Three cases involved the middle transitional zone, three the lower anal canal/anal verge area and
Fig. 1. Diffuse solid sheets of proliferating neoplastic cells replace the dermis with hyperplastic acanthosis of the overlying epidermis (hematoxylin and eosin stain (H&E), original magnification 20×). Inset shows sheets and nests of mononuclear cells with abundant eosinophilic granular cytoplasm and bland nuclei (H&E, 200×). Inner inset shows strong and diffuse staining for S100 (Dako, S100, 200×).
one involved the upper anal canal zone. Six cases involved the left perianal region, four the midline perianal skin and three the right perianal region. The gross appearance was variable according to the type of each lesion (Table 1). The size ranged between 0.4 and 3.0 cm with an average size of 1.2 cm. Follow-up data were available for fifteen cases with a follow-up period that ranged between two months and six years with average of 2.2 years. These cases had an uneventful clinical follow-up, and no local recurrence occurred after complete excision of the lesions. Two cases (cases 11 and 14) had coexistent viral warts and anal fistulas. The other cases were solitary and did not have any associated lesions. Case 1 showed histologic features of granular cell tumor with infiltration and expansion of the dermis by large cells with characteristic eosinophilic granular cytoplasm. These cells were strongly and diffusely positive for S100 (Fig. 1). CD68, HMB45, CD117 and CK were negative. Case 2 showed a polyp of the anal transitional zone (ATZ) mucosa with marked hemorrhage and edema of the underlying stroma (Fig. 2). No evidence of dilated piles or ruptured vessels
Fig. 2. A polyp of the transitional zone with massive hemorrhage and edema of the stroma. (H&E, 20×). Inset shows hemorrhage dissecting through the smooth muscle fibers (H&E, 200×).
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Table 1 Comparison of the clinical and pathologic features of the collected cases of anal and perianal polypoid tumors and tumor-like lesions from 2005 to 2012. SN
Age (years)
Sex
Clinical presentation, duration and initial impression
Location
Gross cut surface appearance and size (cm)
Histology/diagnosis (inferred)
Associated lesions/follow up
1
23
Female
Left anterolateral perianal
2
51
Male
Left lateral anal wall (transitional zone)
Gray white to tan firm polypoid nodule (2.1) Congested edematous polyp (1.4)
28
Male
4
31
Male
Lower posterior anal canal wall, near anal verge Posterior midline perianal (0.9)
White spongy papule (0.8) Polypoid cystic nodule (Fig. 4C)
Granular cell tumor (Fig. 1) Hematoma (spontaneous) (Fig. 2) Lymphangioma. (Fig. 3C) Epidermoid inclusion cyst
None/3 years (NR) None/5 years (NR)
3
5
56
Male
Asymptomatic non-tender mass, few months (lipoma) Bleeding anal polyp and pain, few days (thrombosed hemorrhoid) Asymptomatic non-tender polyp, incidental (anal tag) Perianal nodule and discomfort, few weeks (abscess) Asymptomatic perianal swelling, months (abscess) Painful anal nodule, days to weeks (infected fistula)
Anterior midline perianal (2.0) Posterior midline anal wall (transitional zone)
Pedunculated cystic polyp (Fig. 5) Yellow polypoid nodule (0.6)
Rectal bleeding and discomfort, few months (low rectal/upper anal hemorrhoid) Asymptomatic perianal swelling, months (lipoma) Slightly tender perianal nodule, months (anal polyp/tag) Asymptomatic non-tender perianal nodule, few months (anal tag) Anal pain, weeks to months (perianal wart)
Upper right anal wall (above pectinate line)
Yellow tan soft polypoid swelling (1.8)
Ciliated median raphe cyst Xanthogranuloma (juvenile-type) (Fig. 6) Submucosal lipoma (Fig. 3B)
Right perianal skin
Soft polypoid yellow fatty swelling (3.0) Solid lobulated yellow tan nodule (1.2)
Subcutaneous lipoma Hidradenoma papilliferum
None/5 years (NR) None/2 years (NR)
Left anal verge (0.8)
Pigmented polypoid nodule
Intradermal melanocytic nevus
None/3 years (NR)
Left anal verge/perianal skin
Pigmented warty lesion (1.2)
Seborrheic keratosis (pigmented acanthotic-type) (Fig. 3D)
Asymptomatic perianal swelling, years (?lymphoma) Asymptomatic solitary blackish anal verge papule, months (cyst)
Right posterolateral perianal
Soft yellow fatty lobulated lump (2.7)
Subcutaneous lipoma
Previous treated perianal viral warts + coexistent anal fistula + perianal abscess/6 months (NR) None/2 years (NR)
Left anterolateral perianal
Dark papule (0.4)
Anal pain, perianal nodule, few weeks (cyst) Anal pain and discharge, days (fistula with anal tag) Solitary asymptomatic, non-tender polyp, ? duration, incidental (anal polyp) Tender anal verge/perianal nodule, months (anal polyp) Anal pain with swelling and bleeding, weeks (anal fissure with anal tag)
Posterior midline perianal
Polypoid cystic papule (0.8) Cystic nodule (0.7)
Hair cyst (pigmented follicular cyst) (Fig. 4A) Epidermoid inclusion cyst Ruptured cyst (epidermoid-type) Striated muscle hamartoma (Fig. 7)
6
2.5
Male
7
49
Male
8
38
Male
9
43
Female
10
39
Female
11
36
Male
12
34
Female
13
30
Female
14
37
Male
15
3
Male
16
1.6
Male
17
51
Female
18
28
Female
19
29
Female
20
40
Male
Asymptomatic pigmented perianal nodule, ? duration incidental (anal tag) Asymptomatic, non-tender perianal nodule, few months (cyst)
Left perianal region
Posterior midline perianal Left middle anal canal (transitional zone)
Fleshy firm polyp (0.8)
Left anterolateral perianal
Solid lobulated tan nodule (0.9)
Posterior lower midline anal canal
Yellow tan firm polyp (1.4)
Right posterolateral perianal
Pigmented nodule (0.5)
Left anterolateral perianal
Polypoid cystic nodule (0.9)
Hidradenoma papilliferum (Fig. 4B) Fibrohistiocytic lesion (Benign fibrous histiocytoma) (Fig. 8) Intradermal melanocytic nevus (Fig. 3A) Epidermoid inclusion cyst
None/4 years (NR) None/1 year (NR)
None/NA None/6 years (NR) None/NA
None/1 year (NR)
Coexistent anal fistula/NA None/2 months (NR) None/3 months (NR)
NA/NA
None/3 months (NR)
NA/NA
None/2 months (NR)
SN, serial numbered; NR, no recurrence; NA, not available; ?, unknown. Note: the collected cased were serially numbered according to their chronologic order.
was seen. The patient did not give a history of recent trauma or procedure. This case was diagnosed as spontaneous non-traumatic hematoma. Case 3 showed proliferation of dilated lymphatics lined by endothelial cells and some filled with pink lymph material and few lymphocytes (Fig. 3C). The lymphatics involved the superficial dermis and impinged on the overlying hyperplastic epidermis. This
case represented lymphangioma. Four cases (cases 4, 14, 15 and 20) showed a cyst wall lined by epidermoid-type keratinous epithelium. Case 15 showed a focal area of ruptured cyst wall with foreign body giant cell reaction. No evidence of hair shafts or adnexal structures was seen (Fig. 4C). These cases represented epidermoid-type inclusion cysts. They were found in males. Case 5 showed a cyst wall
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Fig. 3. (A) A polyp of the perianal skin composed of nests and sheets of intradermal melanocytes occupying the dermis without epidermal junctional activity (H&E, 40×). (B) Colorectal mucosa of the upper anal canal with expansion of the submucosa by adipocytes and fibrovascular septa arranged in ill-defined lobules (H&E, 40×). (C) A small polyp formed by dilated lymphatics involving the dermis and impinging on the overlying hyperplastic epidermis (H&E, 40×). (D) A polyp of the anal verge composed of proliferation epidermis with elongated and expanded rete ridges, some with horn cysts and heavy pigmentation (H&E, 40×).
lined by epithelium that varied from non-keratinizing squamous epithelium, transitional epithelium to ciliated columnar epithelium (Fig. 5). Alcian blue special mucin stain was negative, and no goblet cells were seen. No evidence of adnexal structures was seen. This case qualified for median raphe cyst of the anogenital region. Case 6 showed a polypoid nodule composed of sheets of eosinophilic histiocytes with multinucleated giant cells. They were positive for CD68 and negative for CD1a and S100. Touton-type and foreign body-type giant cells were seen (Fig. 6). Focal erosion of the overlying ATZ was seen. The case presented in a 2.5-year-old baby, and the overall histomorphology was consistent with juvenile xanthogranuloma. Three cases (cases 7, 8 and 12) showed typical lobules of mature adipocytes of lipoma. Two cases (cases 8 and 12) involved the perianal subcutaneus tissue. Case 7 involved the submucosa of the upper anal canal. It showed ill-defined lobules of adipocytes with thick blood vessels and thin fibrous septa (Fig. 3B). Cases 9 and 17 showed lobulated nodules composed of adnexal tumor with the characteristic papillary and glandular proliferation of hidradenoma papilliferum (Fig. 4B). They were restricted to females. Two cases (cases 10 and 19) showed typical features of polypoid intradermal melanocytic nevus (Fig. 3A). They were positive for S100 and HMB45. They were found in females. Case 11 showed a warty lesion composed of proliferating pigmented basaloid cells resulting in markedly acanthotic epidermal rete ridges with horn cysts (Fig. 3D). No evidence of koilocytic changes was seen, and HPV immunomarker was negative. We diagnosed this case as seborrheic keratosis of the pigmented acanthotic-type. Case 13 showed a small dermis-based cyst lined by keratinizing squamous epithelium, and the lumen contained frequent pigmented hair shafts (Fig. 4A). This hair cyst was diagnosed as pigmented
follicular cyst. Case 16 showed a polyp with fascicles and thick bundles of haphazardly arranged striated skeletal-type muscle fibers admixed with fibrovascular tissue strands and fatty tissue lobules (Fig. 7). We diagnosed this case as striated muscle hamartoma in a baby. Case 18 showed a polyp composed of well-defined nodule of proliferating fibrohistiocytic cells with a grenz zone from the overlying squamous epithelium. It showed mostly mononuclear foamy histiocytes with foci of fibrous areas with oval to spindle cells and other areas of multinucleated giant cells. The cells were positive for CD68 and negative for CD1a, S100, CD34 and CK. Factor XIIIa was not done because it is not available in our laboratory. We did not find evidence of nuclear pleomorphism, mitotic figures, cholesterol clefts or Touton giant cells. These features, in addition to the occurrence of this lesion in an adult in a non-sun-exposed area, represent an example of a benign fibrohistiocytic lesion most in keeping with benign fibrous histiocytoma. From our retrieved cases, we found one case that was diagnosed as tubulovillous adenoma of the anal canal. However, microscopic re-examination of the H&E slides showed features of inflammatory cloacogenic polyp of the anus rather than true adenoma. Therefore, this case was excluded from our collected list. Discussion The anal canal, by definition, extends from the lower end of the rectum at the anorectal ring to the perianal skin at the anal verge and ranges from 3 to 5 cm [8,10,28]. The anal canal is divided into four zones according to the type of lining epithelium. Below the dentate line is the non-keratinizing squamous mucosa, above is the colorectal-type columnar epithelium and in between
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Fig. 4. (A) The dermis showed a small cyst lined by keratinizing squamous epithelium with frequent pigmented hair shafts in the cavity. The cyst wall is devoid of adnexal structures (H&E, 40×). (B) A polypoid nodule composed of proliferating glandular and papillary lobules with connection to the overlying epidermis and focal surface erosion (H&E, 20×). (C) A perianal cyst lined by keratinizing squamous epithelium. The cyst wall is free of adnexal structures, and the lumen did not contain hair shafts (H&E, 20×).
is a gradual transition zone epithelium [10,28]. The lower anal canal ends at the anal verge or the margin where the squamous mucosa merges with the perianal skin characterized by keratinizing squamous epithelium and the cutaneous appendages, including apocrine glands. Anal glands and anal ducts open into the transitional zone and might extend to the proximal anal canal, thus explaining the occurrence of some unusual submucosal neoplasms [10]. Even though the anal/perianal region is a relatively limited
Fig. 5. An elongated finger-like polyp formed by a cyst (H&E, 20×). Inset shows ciliated glandular epithelium lining the cyst wall (H&E, 400×).
compartment, the histologic variations could result in a variety of epithelial, melanocytic, neuroendocrine, adnexal and mesenchymal neoplasms. The majority of these neoplasms are malignant, while their benign counterparts are relatively uncommon in this region [8,12,13].
Fig. 6. A polyp involves the transitional zone of the anus composed of a welldefined eosinophilic solid nodule (H&E, 20×). Inset shows infiltrate of mononuclear histiocytic cells with frequent multinucleated giant cells and a background of lymphoplasmacytic infiltrate. Focal erosion of the transitional epithelium is evident (H&E, 200×).
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Fig. 7. A polyp formed by a nodule composed of haphazardly arranged bundles of eosinophilic thick muscle fibers (H&E, 20×). Inset shows striated muscle bundles admixed with fibrous strands, blood vessels and fatty lobules (H&E, 100×).
In our study, we found nine cases of benign mesenchymal neoplasms and tumor-like lesions. Granular cell tumors are common mesenchymal neoplasms, but are relatively infrequent findings in the perianal region [15]. Even though lipomas are the commonest benign mesenchymal neoplasms, their occurrence in the anus is in general uncommon [9,17]. Benign histiocytic and fibrohistiocytic lesions are rare in the anogenital region. They might include juvenile xanthogranuloma and fibrous histiocytoma [5,11]. Case 18 showed a benign fibrohistiocytic lesion, most likely benign fibrous histiocytoma, which probably represents the first to involve the ATZ of the anal canal since the case of fibrous histiocytoma in Gomez et al.’s reported series involved the anal margin [11]. Spontaneous perianal and anal hematomas are usually painful lesions that can present as polypoid tumor-like lesions. They are not true hemorrhoids and are not necessarily trauma-related [8,9]. Striated muscle hamartoma is a rare congenital developmental malformation. The reported cases involved the perianal region in female infants [22,23]. Our case involved the transitional zone in a male infant. Even though lymphangiomas are common vascular
Fig. 8. A well-defined polypoid nodule demarcated from the overlying squamous epithelium by a grenz zone (H&E, 40×). Inset shows mononuclear fibrohistiocytic cells arranged in sheets and focal storiform pattern with multinucleated foamy giant cells. Background showed scattered lymphoplasmacytic infiltrate (H&E, 200×).
neoplasms, only one case of a pedunculated polypoid lymphangioma of the anal canal has been reported [26]. We had a similar case that involved the lower anal canal. We found six cases of different types of cysts. Cysts of the perianal region are relatively frequent findings, the most common of which being epidermoid inclusion cysts [4]. Other less common cysts, for example, hair cysts that are usually found in the head and neck region, might rarely involve the anal region [16]. Even though case 13 was suggested clinically to be a vellus hair cyst, we favored follicular pigmented cyst because vellus hair cysts are usually multiple and involve upper body parts. In addition, the presence of pigmented hair shafts favored follicular cyst. Other rare cysts, for example median raphe cysts are almost restricted to the anogenital region [20,21]. They are characterized by the presence of glandular, sometimes ciliated epithelium with or without mucin-secreting cells [20,21]. Two papillary hidradenomas represented the adnexal tumors in our cases. A wide variety of adnexal neoplasms have been reported in the perianal skin; the most common is hidradenoma papilliferum, which is almost exclusive to women [7]. Two intradermal nevi represented the benign melanocytic lesions in our study. Even though one study [18] suggested cytoarchitectural atypia in nevi involving the perianal region and other flexural areas, we did not find such atypia in our cases. We found one case of an epithelial proliferative lesion of the epidermis presenting as anal polyp. Even though seborrheic keratosis is more common in older patients in sun-exposed areas, previous cases involving the perianal region have been reported [24]. The main difficulty in this situation is to differentiate between condyloma accuminata and true seborrheic keratosis. Absence of koilocytes and negativity for HPV marker are helpful. A variety of other rare benign anal polyps have been reported in the literature. They included mesenchymal neoplasms, for example, leiomyomas and fibroadenomas [1,3,6,9]. Few cases of gastric and prostatic tissue heterotopia presenting as anal polyps have also been reported in the literature [9,19,25]. We did not find similar cases in our study. Tubulovillous adenomas of the anal canal were well documented by several case reports [2,14]. Even though one of the retrieved cases in our study was originally labeled as a case of tubulovillous adenoma of the anal canal, re-review of the H&E slides showed histologic features of inflammatory cloacogenic polyp of the anus. In fact, this confusion between these two entities is possible and therefore the separation is important because adenomas have the potential risk of malignant transformation [2,14]. One of the limitations of our study is that five cases did not have a follow-up, and two cases did not have available clinical information regarding associated lesions. In addition, autopsy study to investigate the prevalence of undiscovered anal polyps was not available. Despite these limitations, several lessons could be learned from our study. Even though benign anal polypoid lesions are uncommon, they might present diagnostic challenges for the surgeons and pathologists. This might result in inappropriate management of these neoplasms with the risk of local recurrence if incomplete excision is performed. In addition, some lesions might present diagnostic challenges to the novice pathologists because they are rare and unlikely to present as anal polyps. Interestingly, these lesions were found in infants or adults. No children or teens were identified with such anal polypoid lesions in our review study even though 18 patients in this age group had the usual anal lesions of fibroepithelial polyps/papilla and tags. This finding was comparable to the reported cases and case series in the literature. This might suggest that these lesions are less prevalent in this age group. In general, they were equally distributed in males and females, even though some, for example cysts, were more common in males while others, for example papillary hidradenomas, were exclusive to females. Some of the lesions were asymptomatic surgical findings, for example, nevi, cysts and lipomas. Others, for example, fibrohistiocytic lesions, hematoma and papillary
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hidradenomas were symptomatic causing discomfort, pain or bleeding. The majority were small lesions of less than 2 cm size. This means that many could be unnoticed or incidentally discovered. They were found throughout the anal zones, but were more common in the lower anal canal and the anal verge/perianal region, making their detection by simple rectal examination and palpation easy. All were solitary and were not associated with other neoplasms or tumor-like lesions and therefore are not associated with syndromes or other lesions. In conclusion, benign anal and perianal polypoid lesions are relatively uncommon surgical and pathologic findings. They cover a variety of mesenchymal neoplasms, tumor-like lesions and cysts. Some are common lesions but rare as anal polyps, while others are rare but unique to the anal/perianal region. They might present diagnostic challenges to the surgeons and pathologists. Awareness of these lesions might alleviate these difficulties and allow proper management and diagnosis by the clinicians and pathologists. References [1] J. Alonso Gomez, A. Membrives Obrero, D. Martinez Cecilia, et al., Real anal leiomyoma, J. Gastrointest. Cancer 42 (2011) 54–56. [2] B.S. Anand, G. Verstovsek, G. Cole, Tubulovillous adenoma of anal canal: a case report, World J. Gastroenterol. 12 (2006) 1780–1781. [3] D. Assor, J.B. Davis, Multiple apocrine fibroadenomas of the anal skin, Am. J. Clin. Pathol. 68 (1977) 397–399. [4] G.M. Bonser, F.P. Raper, H.S. Schucksmith, Epidermoid cysts in the region of the rectum and anus, Br. J. Surg. 37 (1950) 303–306. [5] J.C. Bowling, N. Francis, B. Bunker, Solitary anogenital xanthogranuloma, Clin. Exp. Dermatol. 30 (2005) 716–717. [6] W.W. Choi, T.S. Tadros, B. Majmudar, Anal fibroadenoma: report of a common tumor type in an unusual location, South. Med. J. 100 (2007) 914–915. [7] F. Daniel, A. Mahmoudi, V. de Parades, et al., An uncommon perianal nodule: hidradenoma papilliferum, Gastroenterol. Clin. Biol. 31 (2007) 166–168. [8] W.J. Daniel, Anorectal pain, bleeding and lumps, Aust. Fam. Physician 39 (2010) 376–381. [9] J. Denis, R. Ganansia, T. Puy-Montbrun, Rare anorectal pathologic conditions, Curr. Opin. Gen. Surg. (1994) 103–107.
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[10] C. Fenger, Anal canal, in: S.S. Sternberg (Ed.), Histology for Pathologists, 2nd ed., Lippincott Williams & Wilkins, Philadelphia, 1997, pp. 551–571. [11] C.S. Gomez, E. Calonje, C.D.M. Fletcher, Epithelioid bening fibrohisticytoma of the skin: clinic–pathological analysis of 20 cases of a poorly known variant, Histopathology 24 (1994) 123–129. [12] S. Haque, P.J. Dean, Stromal neoplasms of the rectum and anal canal, Hum. Pathol. 23 (1992) 762–767. [13] K.F. Hatch, D.K. Blanchard, G.F. Hatch 3rd, et al., Tumors of the rectum and anal canal, World J. Surg. 24 (2000) 437–443. [14] D. Jain, S. Dhawan, Tubulovillous adenoma of the anal canal: report of 2 rare case with review of literature, Ann. Diagn. Pathol. 16 (2012) 210–213. [15] J. Johnston, E.B. Helwig, Granular cell tumors of the gastrointestinal tract and perianal region: a study of 74 cases, Dig. Dis. Sci. 26 (1981) 807–816. [16] L. Perez-Perez, J. Alvarez, M.M. Pereiro-Ferreiros, et al., Multiple terminal hair cysts in perianal region, Actas Dermosifiliogr. 98 (2007) 213–214. [17] J.A. Robb, R.A. Jones, Spindle cell lipoma in a perianal location, Hum. Pathol. 13 (1982) 1052. [18] F. Rongioletti, R.A. Ball, R. Marcus, R.L. Barnhill, Histopathological features of flexural melanocytic nevi: a study of 40 cases, J. Cutan. Pathol. 27 (2000) 215–217. [19] V. Sabater Marco, M. Martorell Cebollada, Anal polypoid tumor formation as the form of presentation of rectal gastric heterotopia, Rev. Esp. Enferm. Dig. 82 (1992) 56–58 (Abstract). [20] J. Sagar, B. Sagar, A.F. Padel, D.K. Shah, Ciliated median raphe cyst of perineum presenting as perianal polyp: a case report with immunohistochemical study, review of literature, and pathogenesis, ScientificWorldJournal 6 (2006) 2339–2344. [21] M. Scelwyn, Median raphe cyst of the perineum presenting as a perianal polyp, Pathology 28 (1996) 201–202. [22] J.E. Schrecengost, S. Tabbara, J. Patterson, M.R. Wick, Cutaneous mesenchymal hamartoma with mixed myogenous differentiation, J. Cutan. Pathol. 33 (2006) 327–330. [23] Y. Scrivener, P. Petiau, C. Rodier-Bruant, et al., Perianal striated muscle hamartoma, Pediatr. Dermatol. 15 (1998) 274–276. [24] C. Stefanaki, A. Rozakou, K. Stefanaki, et al., Giant perianal seborrhoeic keratosis mimicking condyloma acuminata, Int. J. STD AIDS 20 (2009) 213–214. [25] K. Tekin, U. Sungurtekin, F.O. Aytekin, et al., Ectopic prostatic tissue of the anal canal presenting with rectal bleeding: report of a case, Dis. Colon Rectum 45 (2002) 979–980. [26] J.F. Val-Bernal, M. Mayorga, C. Diego, et al., Pedunculated polypoid lymphangioma of the anal canal, Pathol. Int. 58 (2008) 442–444. [27] G. Vanneuville, P. Dechelotte, T. Scheye, et al., Polypoid formations at the anal margin in infants less than two years old, Eur. J. Pediatr. Surg. 5 (1995) 164–166. [28] E.W. Walls, Observations on the microscopic anatomy of the human anal canal, Br. J. Surg. 45 (1958) 504–512.
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Pathology – Research and Practice journal homepage: www.elsevier.com/locate/prp
Original article
Benign anal and perianal polypoid neoplasms and tumor-like lesions Badr AbdullGaffar a,∗ , Tasnim Keloth b , Mouza Al-Hattawi c , Mamoun Al Marzouqi d , Yousif ElTayeb e a
Pathology Section, Rashid Hospital, Oud Metha Road, Dubai, United Arab Emirates Histopathology Department, Dubai Hospital, United Arab Emirates c General Surgery Unit, Dubai Hospital, United Arab Emirates d Pediatric Surgery Unit, AlWasl Hospital, United Arab Emirates e General Surgery Unit, Rashid Hospital, Dubai, United Arab Emirates b
a r t i c l e
i n f o
Article history: Received 18 June 2012 Received in revised form 28 August 2012 Accepted 13 September 2012 Keywords: Anal canal Perianal Polyps Mesenchymal neoplasms Cysts
a b s t r a c t Mesenchymal anal and perianal tumors are relatively uncommon. The majority are malignant. Benign mesenchymal anal tumors are rare. Some are common stromal neoplasms, but with the rare presentation as anal polyps. Other lesions are rare, but unique to the anal/perianal region. Common keratinous cysts might uncommonly present as anal polyps, while other rare cysts are unique to the anogenital region. A retrospective review study of 493 anal and perianal specimens conducted over seven years showed twenty cases (4.0%) of benign anal polypoid lesions. We excluded the usual fibroepithelial polyps, anal tags, papilla, hemorrhoids and warts. We found six cysts, three lipomas, two papillary hidradenomas, two melanocytic nevi, one hamartoma, one xanthogranuloma, one seborrheic keratosis, one hematoma, one fibrous histiocytoma, one granular cell tumor and one lymphangioma. The male to female ratio was 1.5:1. They were found in adults (mean age 37.8 years) and in infants (mean age 2.4 years). In general, they were smaller than 2 cm. They were either asymptomatic or presented with anal pain, bleeding or lumps. Some were clinically confused with the more common non-neoplastic anal tags, hemorrhoids and fibroepithelial polyps/papilla. A variety of common and rare benign lesions might present as anal polyps with important surgical and pathologic challenges and implications. © 2012 Elsevier GmbH. All rights reserved.
Introduction Mesenchymal tumors of the anal canal and perianal region are relatively rare. The majority are malignant [12,13]. Benign mesenchymal tumors are even rarer clinical and pathologic findings [9,27]. Non-epithelial non-mesenchymal neoplasms and tumorlike lesions of the anal/perianal region are also uncommon findings. Both encompass a variety of neoplastic and nonneoplastic mesenchymal and non-mesenchymal lesions. Some, for example, leiomyomas, granular cell tumors and lipomas, are common neoplasms, but with the rare presentation as anal polyps [1,15,17]. Others, for example, papillary hidradenomas, are unique to the perianal region [7]. These lesions can be confused clinically with the common non-neoplastic causes of anal polyps, for example, anal tags, hemorrhoids and fibroepithelial polyps [8]. This might result in inappropriate management of these neoplasms with the risk of local recurrence. Some might present diagnostic challenges to the novice pathologists. Common epidermoid cysts might unusually present as anal polyps, while other rare developmental cysts are
∗ Corresponding author. Tel.: +971 4 219 2948; fax: +971 4 344 6972. E-mail addresses: [email protected], [email protected] (B. AbdullGaffar). 0344-0338/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.prp.2012.09.004
restricted to the perianal region [4,16,20,21]. We aimed to review the prevalence, distribution and the clinical and pathologic importance of benign anal polypoid neoplasms and tumor-like lesions. In our institution, a retrospective review study confirmed the relative rarity of these benign polypoid lesions of the anal canal and the perianal region with an estimated prevalence of 4.0%. It also highlighted the relatively wide spectrum of lesions that could involve the anal and perianal regions. Even though some of these lesions were benign nonneoplastic lesions, most were clinically important for the subsequent management of patients because they were neoplasms with the potential risk of local recurrence. In addition, some may present diagnostic challenges to the unwary pathologists. Materials and methods A retrospective review study of 387 anal specimens and 106 perianal specimens was conducted over seven years from May 2005 to May 2012. Anal and perianal specimens that were removed for symptomatic anal lesions, as well as those removed as part of lower abdominoperineal resection, those that were incidental findings during routine colonoscopy or pediatric examination for suspected Hirschsprung disease, or incidentally discovered by patients or by their mothers, were collected and reviewed. A computer retrieval
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search was used to collect anal specimens that were clinically and grossly labeled as polyps, polypoid, nodule, swelling, mass, papule or wart. The inclusion criteria were lesions arising from the anal canal from the anal verge to 2 cm above the dentate line, as well as from the perianal skin of the anal margin, but the perineum skin was excluded. Lesions from the rectum proper were excluded. Malignant epithelial neoplasms, malignant melanocytic neoplasms and malignant mesenchymal tumors were excluded. The usual anal tags associated with anal fissures, fibroepithelial polyps, and hypertrophic papilla and inflammatory cloacogenic polyps were excluded, as well as hemorrhoids and viral warts. Anal or perianal inflammatory mass lesions secondary to abscess formation, fissures and fistulas were also excluded from the study. Polypoid anal lesions due to secondary metastases of known primary carcinomas or due to extension from rectum, prostate or female reproductive tract, as well as due to lymphomas and leukemias, were excluded. For each collected case, the gross appearance of cut-surface of the specimen, including the size, was recorded. Sections of 4–6 m thickness were stained with routine hematoxylin and eosin (H&E) stain. Serial sections with multiple deeper levels for each block were performed if necessary. All the H&E slides for each collected case were reviewed. Special stains, for example periodic acid Schiff (PAS), Alcian blue, Masson trichrome, and immunohistochemistry (IHC) study for vimentin, smooth muscle actin (SMA), desmin, S100, CD68, CD117, CD34, ALK, HMB45 and cytokeratin (CK) were performed as directed by the H&E slides examination and as appropriate for the diagnosis of certain cases. The age, gender, the clinical data regarding the presentation of the anal polypoid lesions, including the pre-operative clinical impression, as well as follow up data (when available) and any associated lesions, whether local or systemic, were collected. The topographical localization of each lesion in relation to the different zones of the anal canal was recorded.
Results Of the total 493 anal and perianal specimens, twenty cases (4.0%) showed different types of anal and perianal polypoid neoplasms and tumor-like lesions. We found seven anal cases out of 387 anal specimens and thirteen perianal cases out of 106 perianal specimens. The age range was between 1.6 and 56 years with a mean age of 32.5 years. Three cases were in infants with an average age of 2.4 years. The remaining seventeen cases were found in young and middle-aged adults with an average age of 37.8 years. We did not find similar cases between the age 3 and 20, even though 18 patients within this age range had the usual anal/perianal lesions, for example fibroepithelial polyps, warts, papilla, anal tags, fissures and fistulas. In addition, we found ten infants, apart from our three cases, below the age of 3 with the usual anal polyps. The male to female ratio was 1.2–1 (12 males to 8 females). For the total 493 specimens, the male to female ratio was 2.3–1 (345 males to 148 females). Ten cases presented as asymptomatic polyps or lumps, and ten presented with pain, discomfort, tenderness, bleeding and discharge (Table 1). The duration of the presentation ranged from days to weeks to months in most cases and only few for years depending on the symptoms. Clinically, most were diagnosed as anal tags or the usual anal polyps, while others were labeled as hemorrhoids or abscess. Most of the cysts were correctly labeled as cysts. None of the twenty collected cases were found in the specimens retrieved from abdominoperineal resections, during routine colonoscopy, or during pediatric examination for suspected Hirschsprung disease. They were either clinically symptomatic, presented as palpable polypoid lumps or were incidentally discovered by the parents. Three cases involved the middle transitional zone, three the lower anal canal/anal verge area and
Fig. 1. Diffuse solid sheets of proliferating neoplastic cells replace the dermis with hyperplastic acanthosis of the overlying epidermis (hematoxylin and eosin stain (H&E), original magnification 20×). Inset shows sheets and nests of mononuclear cells with abundant eosinophilic granular cytoplasm and bland nuclei (H&E, 200×). Inner inset shows strong and diffuse staining for S100 (Dako, S100, 200×).
one involved the upper anal canal zone. Six cases involved the left perianal region, four the midline perianal skin and three the right perianal region. The gross appearance was variable according to the type of each lesion (Table 1). The size ranged between 0.4 and 3.0 cm with an average size of 1.2 cm. Follow-up data were available for fifteen cases with a follow-up period that ranged between two months and six years with average of 2.2 years. These cases had an uneventful clinical follow-up, and no local recurrence occurred after complete excision of the lesions. Two cases (cases 11 and 14) had coexistent viral warts and anal fistulas. The other cases were solitary and did not have any associated lesions. Case 1 showed histologic features of granular cell tumor with infiltration and expansion of the dermis by large cells with characteristic eosinophilic granular cytoplasm. These cells were strongly and diffusely positive for S100 (Fig. 1). CD68, HMB45, CD117 and CK were negative. Case 2 showed a polyp of the anal transitional zone (ATZ) mucosa with marked hemorrhage and edema of the underlying stroma (Fig. 2). No evidence of dilated piles or ruptured vessels
Fig. 2. A polyp of the transitional zone with massive hemorrhage and edema of the stroma. (H&E, 20×). Inset shows hemorrhage dissecting through the smooth muscle fibers (H&E, 200×).
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Table 1 Comparison of the clinical and pathologic features of the collected cases of anal and perianal polypoid tumors and tumor-like lesions from 2005 to 2012. SN
Age (years)
Sex
Clinical presentation, duration and initial impression
Location
Gross cut surface appearance and size (cm)
Histology/diagnosis (inferred)
Associated lesions/follow up
1
23
Female
Left anterolateral perianal
2
51
Male
Left lateral anal wall (transitional zone)
Gray white to tan firm polypoid nodule (2.1) Congested edematous polyp (1.4)
28
Male
4
31
Male
Lower posterior anal canal wall, near anal verge Posterior midline perianal (0.9)
White spongy papule (0.8) Polypoid cystic nodule (Fig. 4C)
Granular cell tumor (Fig. 1) Hematoma (spontaneous) (Fig. 2) Lymphangioma. (Fig. 3C) Epidermoid inclusion cyst
None/3 years (NR) None/5 years (NR)
3
5
56
Male
Asymptomatic non-tender mass, few months (lipoma) Bleeding anal polyp and pain, few days (thrombosed hemorrhoid) Asymptomatic non-tender polyp, incidental (anal tag) Perianal nodule and discomfort, few weeks (abscess) Asymptomatic perianal swelling, months (abscess) Painful anal nodule, days to weeks (infected fistula)
Anterior midline perianal (2.0) Posterior midline anal wall (transitional zone)
Pedunculated cystic polyp (Fig. 5) Yellow polypoid nodule (0.6)
Rectal bleeding and discomfort, few months (low rectal/upper anal hemorrhoid) Asymptomatic perianal swelling, months (lipoma) Slightly tender perianal nodule, months (anal polyp/tag) Asymptomatic non-tender perianal nodule, few months (anal tag) Anal pain, weeks to months (perianal wart)
Upper right anal wall (above pectinate line)
Yellow tan soft polypoid swelling (1.8)
Ciliated median raphe cyst Xanthogranuloma (juvenile-type) (Fig. 6) Submucosal lipoma (Fig. 3B)
Right perianal skin
Soft polypoid yellow fatty swelling (3.0) Solid lobulated yellow tan nodule (1.2)
Subcutaneous lipoma Hidradenoma papilliferum
None/5 years (NR) None/2 years (NR)
Left anal verge (0.8)
Pigmented polypoid nodule
Intradermal melanocytic nevus
None/3 years (NR)
Left anal verge/perianal skin
Pigmented warty lesion (1.2)
Seborrheic keratosis (pigmented acanthotic-type) (Fig. 3D)
Asymptomatic perianal swelling, years (?lymphoma) Asymptomatic solitary blackish anal verge papule, months (cyst)
Right posterolateral perianal
Soft yellow fatty lobulated lump (2.7)
Subcutaneous lipoma
Previous treated perianal viral warts + coexistent anal fistula + perianal abscess/6 months (NR) None/2 years (NR)
Left anterolateral perianal
Dark papule (0.4)
Anal pain, perianal nodule, few weeks (cyst) Anal pain and discharge, days (fistula with anal tag) Solitary asymptomatic, non-tender polyp, ? duration, incidental (anal polyp) Tender anal verge/perianal nodule, months (anal polyp) Anal pain with swelling and bleeding, weeks (anal fissure with anal tag)
Posterior midline perianal
Polypoid cystic papule (0.8) Cystic nodule (0.7)
Hair cyst (pigmented follicular cyst) (Fig. 4A) Epidermoid inclusion cyst Ruptured cyst (epidermoid-type) Striated muscle hamartoma (Fig. 7)
6
2.5
Male
7
49
Male
8
38
Male
9
43
Female
10
39
Female
11
36
Male
12
34
Female
13
30
Female
14
37
Male
15
3
Male
16
1.6
Male
17
51
Female
18
28
Female
19
29
Female
20
40
Male
Asymptomatic pigmented perianal nodule, ? duration incidental (anal tag) Asymptomatic, non-tender perianal nodule, few months (cyst)
Left perianal region
Posterior midline perianal Left middle anal canal (transitional zone)
Fleshy firm polyp (0.8)
Left anterolateral perianal
Solid lobulated tan nodule (0.9)
Posterior lower midline anal canal
Yellow tan firm polyp (1.4)
Right posterolateral perianal
Pigmented nodule (0.5)
Left anterolateral perianal
Polypoid cystic nodule (0.9)
Hidradenoma papilliferum (Fig. 4B) Fibrohistiocytic lesion (Benign fibrous histiocytoma) (Fig. 8) Intradermal melanocytic nevus (Fig. 3A) Epidermoid inclusion cyst
None/4 years (NR) None/1 year (NR)
None/NA None/6 years (NR) None/NA
None/1 year (NR)
Coexistent anal fistula/NA None/2 months (NR) None/3 months (NR)
NA/NA
None/3 months (NR)
NA/NA
None/2 months (NR)
SN, serial numbered; NR, no recurrence; NA, not available; ?, unknown. Note: the collected cased were serially numbered according to their chronologic order.
was seen. The patient did not give a history of recent trauma or procedure. This case was diagnosed as spontaneous non-traumatic hematoma. Case 3 showed proliferation of dilated lymphatics lined by endothelial cells and some filled with pink lymph material and few lymphocytes (Fig. 3C). The lymphatics involved the superficial dermis and impinged on the overlying hyperplastic epidermis. This
case represented lymphangioma. Four cases (cases 4, 14, 15 and 20) showed a cyst wall lined by epidermoid-type keratinous epithelium. Case 15 showed a focal area of ruptured cyst wall with foreign body giant cell reaction. No evidence of hair shafts or adnexal structures was seen (Fig. 4C). These cases represented epidermoid-type inclusion cysts. They were found in males. Case 5 showed a cyst wall
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Fig. 3. (A) A polyp of the perianal skin composed of nests and sheets of intradermal melanocytes occupying the dermis without epidermal junctional activity (H&E, 40×). (B) Colorectal mucosa of the upper anal canal with expansion of the submucosa by adipocytes and fibrovascular septa arranged in ill-defined lobules (H&E, 40×). (C) A small polyp formed by dilated lymphatics involving the dermis and impinging on the overlying hyperplastic epidermis (H&E, 40×). (D) A polyp of the anal verge composed of proliferation epidermis with elongated and expanded rete ridges, some with horn cysts and heavy pigmentation (H&E, 40×).
lined by epithelium that varied from non-keratinizing squamous epithelium, transitional epithelium to ciliated columnar epithelium (Fig. 5). Alcian blue special mucin stain was negative, and no goblet cells were seen. No evidence of adnexal structures was seen. This case qualified for median raphe cyst of the anogenital region. Case 6 showed a polypoid nodule composed of sheets of eosinophilic histiocytes with multinucleated giant cells. They were positive for CD68 and negative for CD1a and S100. Touton-type and foreign body-type giant cells were seen (Fig. 6). Focal erosion of the overlying ATZ was seen. The case presented in a 2.5-year-old baby, and the overall histomorphology was consistent with juvenile xanthogranuloma. Three cases (cases 7, 8 and 12) showed typical lobules of mature adipocytes of lipoma. Two cases (cases 8 and 12) involved the perianal subcutaneus tissue. Case 7 involved the submucosa of the upper anal canal. It showed ill-defined lobules of adipocytes with thick blood vessels and thin fibrous septa (Fig. 3B). Cases 9 and 17 showed lobulated nodules composed of adnexal tumor with the characteristic papillary and glandular proliferation of hidradenoma papilliferum (Fig. 4B). They were restricted to females. Two cases (cases 10 and 19) showed typical features of polypoid intradermal melanocytic nevus (Fig. 3A). They were positive for S100 and HMB45. They were found in females. Case 11 showed a warty lesion composed of proliferating pigmented basaloid cells resulting in markedly acanthotic epidermal rete ridges with horn cysts (Fig. 3D). No evidence of koilocytic changes was seen, and HPV immunomarker was negative. We diagnosed this case as seborrheic keratosis of the pigmented acanthotic-type. Case 13 showed a small dermis-based cyst lined by keratinizing squamous epithelium, and the lumen contained frequent pigmented hair shafts (Fig. 4A). This hair cyst was diagnosed as pigmented
follicular cyst. Case 16 showed a polyp with fascicles and thick bundles of haphazardly arranged striated skeletal-type muscle fibers admixed with fibrovascular tissue strands and fatty tissue lobules (Fig. 7). We diagnosed this case as striated muscle hamartoma in a baby. Case 18 showed a polyp composed of well-defined nodule of proliferating fibrohistiocytic cells with a grenz zone from the overlying squamous epithelium. It showed mostly mononuclear foamy histiocytes with foci of fibrous areas with oval to spindle cells and other areas of multinucleated giant cells. The cells were positive for CD68 and negative for CD1a, S100, CD34 and CK. Factor XIIIa was not done because it is not available in our laboratory. We did not find evidence of nuclear pleomorphism, mitotic figures, cholesterol clefts or Touton giant cells. These features, in addition to the occurrence of this lesion in an adult in a non-sun-exposed area, represent an example of a benign fibrohistiocytic lesion most in keeping with benign fibrous histiocytoma. From our retrieved cases, we found one case that was diagnosed as tubulovillous adenoma of the anal canal. However, microscopic re-examination of the H&E slides showed features of inflammatory cloacogenic polyp of the anus rather than true adenoma. Therefore, this case was excluded from our collected list. Discussion The anal canal, by definition, extends from the lower end of the rectum at the anorectal ring to the perianal skin at the anal verge and ranges from 3 to 5 cm [8,10,28]. The anal canal is divided into four zones according to the type of lining epithelium. Below the dentate line is the non-keratinizing squamous mucosa, above is the colorectal-type columnar epithelium and in between
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Fig. 4. (A) The dermis showed a small cyst lined by keratinizing squamous epithelium with frequent pigmented hair shafts in the cavity. The cyst wall is devoid of adnexal structures (H&E, 40×). (B) A polypoid nodule composed of proliferating glandular and papillary lobules with connection to the overlying epidermis and focal surface erosion (H&E, 20×). (C) A perianal cyst lined by keratinizing squamous epithelium. The cyst wall is free of adnexal structures, and the lumen did not contain hair shafts (H&E, 20×).
is a gradual transition zone epithelium [10,28]. The lower anal canal ends at the anal verge or the margin where the squamous mucosa merges with the perianal skin characterized by keratinizing squamous epithelium and the cutaneous appendages, including apocrine glands. Anal glands and anal ducts open into the transitional zone and might extend to the proximal anal canal, thus explaining the occurrence of some unusual submucosal neoplasms [10]. Even though the anal/perianal region is a relatively limited
Fig. 5. An elongated finger-like polyp formed by a cyst (H&E, 20×). Inset shows ciliated glandular epithelium lining the cyst wall (H&E, 400×).
compartment, the histologic variations could result in a variety of epithelial, melanocytic, neuroendocrine, adnexal and mesenchymal neoplasms. The majority of these neoplasms are malignant, while their benign counterparts are relatively uncommon in this region [8,12,13].
Fig. 6. A polyp involves the transitional zone of the anus composed of a welldefined eosinophilic solid nodule (H&E, 20×). Inset shows infiltrate of mononuclear histiocytic cells with frequent multinucleated giant cells and a background of lymphoplasmacytic infiltrate. Focal erosion of the transitional epithelium is evident (H&E, 200×).
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Fig. 7. A polyp formed by a nodule composed of haphazardly arranged bundles of eosinophilic thick muscle fibers (H&E, 20×). Inset shows striated muscle bundles admixed with fibrous strands, blood vessels and fatty lobules (H&E, 100×).
In our study, we found nine cases of benign mesenchymal neoplasms and tumor-like lesions. Granular cell tumors are common mesenchymal neoplasms, but are relatively infrequent findings in the perianal region [15]. Even though lipomas are the commonest benign mesenchymal neoplasms, their occurrence in the anus is in general uncommon [9,17]. Benign histiocytic and fibrohistiocytic lesions are rare in the anogenital region. They might include juvenile xanthogranuloma and fibrous histiocytoma [5,11]. Case 18 showed a benign fibrohistiocytic lesion, most likely benign fibrous histiocytoma, which probably represents the first to involve the ATZ of the anal canal since the case of fibrous histiocytoma in Gomez et al.’s reported series involved the anal margin [11]. Spontaneous perianal and anal hematomas are usually painful lesions that can present as polypoid tumor-like lesions. They are not true hemorrhoids and are not necessarily trauma-related [8,9]. Striated muscle hamartoma is a rare congenital developmental malformation. The reported cases involved the perianal region in female infants [22,23]. Our case involved the transitional zone in a male infant. Even though lymphangiomas are common vascular
Fig. 8. A well-defined polypoid nodule demarcated from the overlying squamous epithelium by a grenz zone (H&E, 40×). Inset shows mononuclear fibrohistiocytic cells arranged in sheets and focal storiform pattern with multinucleated foamy giant cells. Background showed scattered lymphoplasmacytic infiltrate (H&E, 200×).
neoplasms, only one case of a pedunculated polypoid lymphangioma of the anal canal has been reported [26]. We had a similar case that involved the lower anal canal. We found six cases of different types of cysts. Cysts of the perianal region are relatively frequent findings, the most common of which being epidermoid inclusion cysts [4]. Other less common cysts, for example, hair cysts that are usually found in the head and neck region, might rarely involve the anal region [16]. Even though case 13 was suggested clinically to be a vellus hair cyst, we favored follicular pigmented cyst because vellus hair cysts are usually multiple and involve upper body parts. In addition, the presence of pigmented hair shafts favored follicular cyst. Other rare cysts, for example median raphe cysts are almost restricted to the anogenital region [20,21]. They are characterized by the presence of glandular, sometimes ciliated epithelium with or without mucin-secreting cells [20,21]. Two papillary hidradenomas represented the adnexal tumors in our cases. A wide variety of adnexal neoplasms have been reported in the perianal skin; the most common is hidradenoma papilliferum, which is almost exclusive to women [7]. Two intradermal nevi represented the benign melanocytic lesions in our study. Even though one study [18] suggested cytoarchitectural atypia in nevi involving the perianal region and other flexural areas, we did not find such atypia in our cases. We found one case of an epithelial proliferative lesion of the epidermis presenting as anal polyp. Even though seborrheic keratosis is more common in older patients in sun-exposed areas, previous cases involving the perianal region have been reported [24]. The main difficulty in this situation is to differentiate between condyloma accuminata and true seborrheic keratosis. Absence of koilocytes and negativity for HPV marker are helpful. A variety of other rare benign anal polyps have been reported in the literature. They included mesenchymal neoplasms, for example, leiomyomas and fibroadenomas [1,3,6,9]. Few cases of gastric and prostatic tissue heterotopia presenting as anal polyps have also been reported in the literature [9,19,25]. We did not find similar cases in our study. Tubulovillous adenomas of the anal canal were well documented by several case reports [2,14]. Even though one of the retrieved cases in our study was originally labeled as a case of tubulovillous adenoma of the anal canal, re-review of the H&E slides showed histologic features of inflammatory cloacogenic polyp of the anus. In fact, this confusion between these two entities is possible and therefore the separation is important because adenomas have the potential risk of malignant transformation [2,14]. One of the limitations of our study is that five cases did not have a follow-up, and two cases did not have available clinical information regarding associated lesions. In addition, autopsy study to investigate the prevalence of undiscovered anal polyps was not available. Despite these limitations, several lessons could be learned from our study. Even though benign anal polypoid lesions are uncommon, they might present diagnostic challenges for the surgeons and pathologists. This might result in inappropriate management of these neoplasms with the risk of local recurrence if incomplete excision is performed. In addition, some lesions might present diagnostic challenges to the novice pathologists because they are rare and unlikely to present as anal polyps. Interestingly, these lesions were found in infants or adults. No children or teens were identified with such anal polypoid lesions in our review study even though 18 patients in this age group had the usual anal lesions of fibroepithelial polyps/papilla and tags. This finding was comparable to the reported cases and case series in the literature. This might suggest that these lesions are less prevalent in this age group. In general, they were equally distributed in males and females, even though some, for example cysts, were more common in males while others, for example papillary hidradenomas, were exclusive to females. Some of the lesions were asymptomatic surgical findings, for example, nevi, cysts and lipomas. Others, for example, fibrohistiocytic lesions, hematoma and papillary
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hidradenomas were symptomatic causing discomfort, pain or bleeding. The majority were small lesions of less than 2 cm size. This means that many could be unnoticed or incidentally discovered. They were found throughout the anal zones, but were more common in the lower anal canal and the anal verge/perianal region, making their detection by simple rectal examination and palpation easy. All were solitary and were not associated with other neoplasms or tumor-like lesions and therefore are not associated with syndromes or other lesions. In conclusion, benign anal and perianal polypoid lesions are relatively uncommon surgical and pathologic findings. They cover a variety of mesenchymal neoplasms, tumor-like lesions and cysts. Some are common lesions but rare as anal polyps, while others are rare but unique to the anal/perianal region. They might present diagnostic challenges to the surgeons and pathologists. Awareness of these lesions might alleviate these difficulties and allow proper management and diagnosis by the clinicians and pathologists. References [1] J. Alonso Gomez, A. Membrives Obrero, D. Martinez Cecilia, et al., Real anal leiomyoma, J. Gastrointest. Cancer 42 (2011) 54–56. [2] B.S. Anand, G. Verstovsek, G. Cole, Tubulovillous adenoma of anal canal: a case report, World J. Gastroenterol. 12 (2006) 1780–1781. [3] D. Assor, J.B. Davis, Multiple apocrine fibroadenomas of the anal skin, Am. J. Clin. Pathol. 68 (1977) 397–399. [4] G.M. Bonser, F.P. Raper, H.S. Schucksmith, Epidermoid cysts in the region of the rectum and anus, Br. J. Surg. 37 (1950) 303–306. [5] J.C. Bowling, N. Francis, B. Bunker, Solitary anogenital xanthogranuloma, Clin. Exp. Dermatol. 30 (2005) 716–717. [6] W.W. Choi, T.S. Tadros, B. Majmudar, Anal fibroadenoma: report of a common tumor type in an unusual location, South. Med. J. 100 (2007) 914–915. [7] F. Daniel, A. Mahmoudi, V. de Parades, et al., An uncommon perianal nodule: hidradenoma papilliferum, Gastroenterol. Clin. Biol. 31 (2007) 166–168. [8] W.J. Daniel, Anorectal pain, bleeding and lumps, Aust. Fam. Physician 39 (2010) 376–381. [9] J. Denis, R. Ganansia, T. Puy-Montbrun, Rare anorectal pathologic conditions, Curr. Opin. Gen. Surg. (1994) 103–107.
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