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Retrorectal cyst: a rare tumor frequently misdiagnosed
Retrorectal Cyst: A Rare Tumor Frequently Misdiagnosed Marc A Singer, MD, Jose´ R Cintron, MD, FACS, Joseph E Martz, MD, David J Schoetz, MD, FACS, Herand Abcarian, MD, FACS The rarity of retrorectal cysts and their nonspecific clinical presentations often lead to misdiagnoses and inappropriate operations. In recent years, several such patients have been referred to our institutions for evaluation and treatment of misdiagnosed retrorectal cysts. A review of these patients is presented. STUDY DESIGN: Medical records of the colorectal surgery divisions at two institutions were reviewed. Patients found to have previously misdiagnosed retrorectal cysts were identified. Preliminary diagnoses, radiologic examinations, operative procedures, and final diagnoses were obtained. RESULTS: Seven patients with retrorectal cysts who had been misdiagnosed before referral were identified. These patients had been treated for fistulae in ano, pilonidal cysts, perianal abscesses; psychogenic, lower back, posttraumatic, or postpartum pain, and proctalgia fugax before the correct diagnosis was made. Patients underwent an average of 4.1 operative procedures. Physical examination in combination with CT scanning made the correct diagnosis in all patients. All patients underwent successful resection through a parasacrococcygeal approach, and six of seven did not require coccygectomy. The resected tumors included four hamartomas, two epidermoid cysts, and one enteric duplication cyst. CONCLUSIONS: Retrorectal cysts are a rare entity that can be difficult to diagnose without a high index of clinical suspicion. A history of multiple unsuccessful procedures should alert the clinician to the diagnosis of retrorectal cyst. Once suspected, the correct diagnosis can be made with physical examination and a CT scan before a definitive surgical procedure. ( J Am Coll Surg 2003;196: 880–886. © 2003 by the American College of Surgeons) BACKGROUND:
Retrorectal cysts are a heterogeneous collection of lesions contained within the retrorectal space. The rarity of these tumors in adults and their nonspecific clinical presentations often lead to misdiagnoses. Patients frequently undergo multiple operations before the correct diagnosis is made. Several patients have been referred to the University of Illinois at Chicago and The Lahey Clinic Divisions of Colorectal Surgery for the treatment of previously misdiagnosed retrorectal cysts in recent
years. These cases are presented to illustrate several major clinical features. METHODS Medical records of the Divisions of Colorectal Surgery at the University of Illinois at Chicago and The Lahey Clinic were searched. Patients treated for retrorectal cysts were identified. From this group, patients with a referring diagnosis other than retrorectal cyst were identified. Patient demographics, referring diagnoses, diagnostic procedures, surgical history, and final pathology were collected.
No competing interests declared.
Supported in part by the Eleanor B Pillsbury Fellowship at the University of Illinois Hospital.
RESULTS The search identified seven patients. All seven had been treated at outside institutions before referral to either the University of Illinois at Chicago or the Lahey Clinic Divisions of Colorectal Surgery. There were six women and one man. Mean age was 36 years, with a range of 17 to 49 years. Presenting symptoms included lower back
Received May 29, 2002; Revised November 6, 2002; Accepted November 6, 2002. From the Departments of Surgery, The University of Illinois at Chicago, Chicago, IL (Singer, Cintron, Abcarian) and The Lahey Clinic, Burlington, MA (Martz, Schoetz). Correspondence address: Dr. Herand Abcarian, Department of Surgery, University of Illinois, 840 South Wood St, Room 518, M/C 958, Chicago, IL 60612.
© 2003 by the American College of Surgeons Published by Elsevier Science Inc.
880
ISSN 1072-7515/03/$21.00 doi:10.1016/S1072-7515(03)00133-9
Singer et al
Vol. 196, No. 6, June 2003
Misdiagnosed Retrorectal Cysts
881
Table 1. Patient Characteristics Pt. No. Age Gender (y)
Symptoms
Duration (y)
1
17
F
Back pain
1
2
18
F
4
3
44
F
Draining paracoccygeal sinus Rectal pain
4 5
33 45
F F
5 2
6
49
M
Rectal pain Pain; swelling; constipation; pain with ambulation Perianal pain; fevers
7
43
F
Draining wound
11
8
3
Previous treatments
Misdiagnoses
No. of procedures
Treatment
Final diagnosis
Drainage catheter ⫻ 2; I Perirectal abscess; ⫹ D; biopsy posttraumatic pain; 3 “pilonidal excisions”; Pilonidal CT fistulogram
5
Excision
Enteric cyst
5
Excision
Epidermoid cyst
I ⫹ D ⫻ 2; fistulogram; Presacral abscess, drainage catheter fistula in ano Colonoscopy ⫻ 3; Psychogenic pain CT myelogram; Pilonidal cyst aspiration of cyst ⫻ 2;
5
Excision
4 4
Excision Excision
Epidermoid cyst Hamartoma Hamartoma
Fistula in ano; I ⫹ D; I ⫹ D with perianal abscess excision fistula tract; I ⫹ D with fistulotomy; fistulectomy with malecot; curettage with catheter; sinogram with downsizing catheters Fistulectomy; closure Fistula in ano; internal and drainage perianal abscess
7
Excision with Hamartoma coccygectomy
3
Excision
Hamartoma
I ⫹ D, incision and draining.
pain, rectal or anal pain, constipation, swelling, pain with ambulation, fevers, and chronically draining wounds. The average duration of symptoms at presentation was 4.9 years, with a range of 1 to 11 years. Initial diagnoses included perianal abscess, fistula in ano, posttraumatic pain, pilonidal cyst, presacral abscess, postpartum pain, and psychogenic pain. The patients had undergone a mean of 4.7 operations or invasive procedures to diagnose and treat their disease (Table 1) excluding imaging studies. The correct diagnosis was made in all seven patients based on history, digital rectal examination, and CT scanning. All patients were treated with excision of the cyst by the posterior parasacrococcygeal approach. Only one patient required a coccygectomy during the excision. Final diagnoses included four hamartomas, two epidermoid cysts, and one enteric duplication cyst. A selected patient is presented below. It is representative of this patient group and illustrates several important features common to these patients. Case presentation
An 18-year-old woman complained of a persistently draining paracoccygeal sinus for 4 years. The drainage
was usually serosanguinous, and occasionally purulent. She also had intermittent fevers. She had previously undergone three operative resections for suspected pilonidal disease, with immediate recurrence of her symptoms after each operation. The patient was referred to our institution for evaluation of her persistent “pilonidal disease.” Examination revealed the external opening of a well epithelialized tract in the paracoccygeal region with serosanguinous drainage (Fig. 1). Rectal examination was unremarkable and showed no evidence of a primary fistulous opening. Laboratory tests were normal. A CT fistulogram of the abdomen and pelvis demonstrated a well-circumscribed 3 ⫻ 3-cm cystic mass in the retrorectal space (Fig. 2). There was no evidence of local invasion or bony destruction. Based on radiographic findings and the history of recurrent abscesses, a retrorectal cyst was diagnosed and the patient was taken to the operating room for excision of the cyst. The patient was operated on under spinal anesthesia and in the prone jack-knife position. A Foley catheter was introduced into the cyst through the sinus tract, and the catheter balloon was inflated with 5 mL of saline. A parasacrococcygeal incision was made. Levator ani mus-
882
Singer et al
Misdiagnosed Retrorectal Cysts
J Am Coll Surg
moid cyst. The patient did well postoperatively and has not had a recurrence of symptoms in more than 2 years.
Figure 1. Photograph of wound. Note the postanal dimple, which can be mistaken for a fistula in ano.
cles were divided and dissection continued into the supralevator space. The retrorectal space was then explored without removal of the coccyx. The cyst, which was well demarcated because of the inflated Foley catheter balloon, was carefully dissected off the posterior wall of the rectum. The excised cyst was then opened for examination (Fig. 3), and the diagnosis of an epidermoid developmental cyst was made. The muscle layers were reapproximated and the wound was closed over a suction drain. Pathology confirmed the diagnosis of an epider-
DISCUSSION The true incidence of retrorectal cysts is difficult to estimate because there have been few large series published. Jao and colleagues1 have estimated the incidence of retrorectal cysts to be approximately 1 in 40,000 hospital admissions to the Mayo Clinic. The etiology of the cysts is varied (Table 2). Because this list is extensive, a comprehensive review of each type will not be presented. Rather, the types of cysts in the case series will be briefly reviewed. About half of all retrorectal tumors are congenital lesions, and most of those are developmental cysts (epidermoid, dermoid, mucus-secreting cysts, and teratomas). Developmental cysts can arise from any of the germ layers. A strong female predominance is associated with developmental cysts.1 Both epidermoid and dermoid cysts result from closure defects of the ectodermal tube with inclusions of skin, but dermoid cysts also contain skin appendages, such as sweat glands, hair follicles, or sebaceous glands.1 The cysts can communicate with the skin surface, causing a characteristic postanal dimple. Approximately one-third will become infected.2 If an infected cyst communicates with a postanal dimple,
Figure 2. CT fistulogram. (Left) The patient in the prone position as contrast material is injected into the external opening and is obviously filling the cyst cavity. There is clearly no communication with the rectum. (Right) The patient in the supine position and lateral displacement of the rectum by the cyst.
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Table 2. Differential Diagnosis of a Retrorectal Cyst Congenital Osseous Epidermoid Dermoid Mucus-secreting Teratoma Chordoma Teratocarcinoma Adrenal rest tumor Anterior sacral meningocele Duplication of rectum
Osteoma Osteogenic sarcoma Simple bone cyst, sacrum Ewing’s tumor Chondromyxosarcoma Aneurysmal bone cyst Giant cell tumor
Miscellaneous Inflammatory
Figure 3. Photograph of epidermoid cyst.
the appearance can be quite similar to a fistula in ano or pilonidal disease, resulting in misdiagnosis. Enterogenous cysts result from the sequestration of the developing hindgut. They tend to be multilocular, with one major cyst and several adjacent minor cysts. Like dermoid and epidermoid cysts, these are also more common in women and tend to become infected. If not infected or malignant, they will usually remain asymptomatic. They are almost always benign, although malignancy has been reported in the literature.3 Tailgut cysts (also called cystic hamartomas or mucus secreting cysts) are remnants of the embryonic portion of the gut extending beyond the anus. This portion of the gut normally regresses with the embryonic tail.4 They can be differentiated from dermoid cysts by the lack of dermal appendages, from enteric cysts by the lack of intestinal epithelium, and from teratomas that contain all three germ layers. Complete excision of the entire cyst will prevent recurrence. Benign lesions are more common than malignant lesions in most reported series.1,5,6 In adults, the risk of malignancy in cystic lesions of any type is somewhere between 10% and 60%.5 The most common retrorectal malignancy is the chordoma, which arises from remnants of the fetal notochord. Malignancy is equally common in men and women, despite the fact that retrorectal lesions are much more common in women. This might
Foreign body granuloma Perineal abscess Internal fistula Pelvirectal abscess Chronic infectious granuloma
Neurogenic Neurofibroma and sarcoma Neurilemoma Ependymoma Ganglioneuroma Neurofibrosarcoma
Metastatic carcinoma Liposarcoma Hemangioendothelial sarcoma Lymphangioma Extra-abdominal desmoid tumor Plasma cell myeloma Malignant neoplasm of unknown type Lipoma Fibroma Fibrosarcoma Leiomyoma Leiomyosarcoma Hemangioma Pericytoma Endothelioma
(From: Uhlig BE, Johnson RL. Presacral tumors and cysts in adults. Dis Colon Rectum 1975;18:581–596, with permission.)
relate to the fact that malignant tumors are usually symptomatic and will present themselves; benign tumors are usually asymptomatic and remain undetected until the childbearing years. The frequency of pelvic examinations during that time might account for the increased incidence in women. The clinical presentation of retrorectal cysts is often nonspecific or misleading. The most common symptom is pain, especially if the cyst is infected or malignant. The pain is typically vague, poorly localized, and dull. If the tumor has invaded the sacral plexus, then pain can be experienced in the legs or buttocks. The pain can be postural, especially with chordomas. Infection can be the presenting symptom in some patients. The appearance of a draining sinus or fistula tract is what frequently leads to misdiagnosis as pilonidal abscess, perianal abscess, or fistula in ano. A history of multiple drainage procedures and recurrences should be
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Misdiagnosed Retrorectal Cysts
J Am Coll Surg
Figure 4. Fistulogram. The catheter has been inserted into the cutaneous wound. The contrast fills the cyst, but does not communicate with the rectum. Note the lobular appearance of the cyst.
a warning to the clinician that an undiagnosed retrorectal cyst exists. Large masses can cause constipation, and nerve invasion can result in fecal incontinence or urinary symptoms. A previously undiagnosed tumor can grow large enough to obstruct labor.7 Anterior sacral meningoceles can present as headache or recurrent meningitis.7 Physical examination is diagnostic in most cases and can also determine the operative approach for most patients. In the Mayo Clinic series, 97% of tumors were detectable by digital rectal examination alone.1 A retrorectal mass can be palpated through the posterior wall of the rectum but cystic lesions can be more difficult to detect. Sigmoidoscopy should be performed in all cases to rule out invasion of the rectal wall. An infected mass that is palpable in the posterior perineum can be misdiagnosed as a perirectal abscess or infected pilonidal cyst. A “pilonidal cyst” anterior to the coccyx should suggest an alternative diagnosis. A postanal dimple suggests the presence of a developmental cyst (Fig. 1). Laxity of the sphincters or anesthesia of the perineum signifies invasion of the sacral nerves. Plain x-rays can be valuable in diagnosing retrorectal tumors. Solid tumors are often seen compressing, invading, or displacing the sacrum on the x-ray. Invasion or bony destruction suggests malignancy.4 Anterior sacral meningoceles can have the pathognomonic scimitar sign caused by a unilateral sacral defect. Chronic fistulae can be evaluated with a fistulogram, which documents anatomy and rules out communication with the rectum (Fig. 4). CT scans have become the most valuable diagnostic
modality for evaluating retrorectal tumors. CT scans can determine if the lesion is cystic or solid, define the extent of the tumor and its relationship to surrounding structures, and help plan an operative approach (Fig. 2). MRI has been used with equal success in our experience, but published data are lacking. Myelography can help to confirm involvement of the central nervous system. Endorectal ultrasonography can be beneficial in evaluating retrorectal cysts.5 If a lesion is thought to be resectable, then there is no role for preoperative biopsy. Even benign lesions must be completely resected because there is an increased chance of becoming infected or malignant with time. In addition, needle biopsy puts the patient at risk for seeding of the tract with malignant cells, and at risk for meningitis if a meningocele is present. Only if a lesion is thought to be inoperable, can a biopsy be useful to determine adjuvant therapy. If a biopsy must be performed, then a CT-guided extrarectal and presacral approach is recommended.5 Transrectal biopsy should be avoided because of the risk of infection or seeding the rectum with tumor. Choices of operative approach include the abdominal approach, posterior approach, or a combined technique. The abdominal approach is best for high retrorectal tumors. If the tumor invades the rectum, resection would be required. The posterior approach is most useful for low-lying lesions and infected cysts. If superior border of the tumor can be palpated during digital examination, the posterior approach should be successful. The patient is
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Figure 5. Resection via posterior approach. The operation is performed with the patient in the prone jack-knife position, A. The location of the cyst between the presacral fascia and rectum is illustrated, B, and the parasacrococcygeal skin incision is shown on C. The anococcygeal ligament is divided transversely (arrow), and the gluteus maximus muscle can be partially divided to gain exposure, D. The cyst is readily identified and dissected sharply from the rectal wall and lateral attachments, E. (Adapted from Abel ME, Nelson R, Prasad ML, et al. Parasacrococcygeal approach for the resection of retrorectal development cysts. Dis Colon Rectum 1985;28:855– 858, with permission.)
placed in the prone jack-knife position. A parasacrococcygeal, curvilinear, or horizontal incision can be used. The anococcygeal ligament and the levator ani muscle are divided, and the supralevator space is entered. Some surgeons prefer to remove the coccyx routinely, but Abel and colleagues2 demonstrated that tumors can successfully be excised through the paracoccygeal approach without removing the coccyx (Fig. 5). If the tumor extends in the cephalad direction, hemostasis can be difficult. If hemorrhage is uncontrollable, then the patient should be repositioned and a laparotomy performed. Infected cysts should be drained, and then excised electively at a later time. Tumors greater than 3 or 4 cm or those rising above the sacral promontory might be best approached with a combined abdominosacral approach.8,9 This permits maximal vascular control and good exposure for protection of the sacral nerves. Laparotomy is performed first, followed by posterior dissection and resection. Mobilization of the rectum from above can make resolution of the mass from below a simpler procedure.5 Irrespective of the approach, all patients should un-
dergo preoperative mechanical and antibiotic preparation, in case the cyst connects with or tumor invades the rectum and partial rectal excision and closure is needed. Longterm survival after treatment of retrorectal cyst is difficult to estimate because of the wide variety of pathology comprising this category of tumor. At the Mayo Clinic, 5-year survival for chordoma was 75%, but only 17% for other malignancies.1 In cases of local recurrence, most reexcision should be attempted. Surgical exposure to the retrorectal space is limited at best, so complete excision at the first attempt is critical. Radiotherapy can provide palliation for some inoperable tumors. Chemotherapy has essentially no role at this time. Although small in number, this case series illustrates several important features of retrorectal cysts, ie, delay in diagnosis, misdiagnosis, and errors in treatment. Presence of postanal dimple, palpable mass, history of recurrent disease, lack of an infected anal gland, and fullness in the precoccygeal region should all suggest the presence of retrorectal cyst. CT scan (with or without fistulogram) is the diagnostic procedure of choice for retro-
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rectal cyst. Most patients can be managed through parasacrococcygeal approach without coccygectomy.2 In conclusion, retrorectal cyst is a rare entity that can be difficult to diagnose. Patients can be misdiagnosed and inappropriately treated for many years. Physical examination in combination with CT scanning will make the diagnosis in all patients. Complete surgical excision is required in all patients, and can usually be accomplished through the posterior approach. Author contributions
Study conception and design: Cintron, Schoetz, Abcarian Acquisition of data: Singer, Martz Analysis and interpretation of data: Singer, Cintron, Abcarian Drafting of manuscript: Singer Critical revision: Cintron, Abcarian Statistical expertise: Singer, Abcarian Supervision: Abcarian
J Am Coll Surg
REFERENCES 1. Jao SW, Beart RW Jr, Spencer RJ, et al. Retrorectal tumors: Mayo Clinic Experience, 1960-1979. Dis Colon Rectum 1985;28:644– 652. 2. Abel ME, Nelson R, Prasad ML, et al. Parasacrococcygeal approach for the resection of retrorectal developmental cysts. Dis Colon Rectum 1985;28:855–858. 3. Springall RG, Griffiths JD. Malignant change in retrorectal duplication. J R Soc Med 1990;83:185–186. 4. Hjermstad BM, Helwig EB. Tailgut cysts. Report of 53 cases. Am J Clin Pathol 1988;89:139–147. 5. Gordon PH. Retrorectal tumors. In: Gordon PH, Nivatvongs S, eds. Principles and practice of surgery for the colon, rectum, and anus. 2nd ed. St Louis, MO: Quality Medical Publishing; 1999: 428–445. 6. Gray SW, Singhabhandhu B, Smith RA, et al. Sacrococcygeal chordoma: report of a case and review of the literature. Surgery 1975;78:573–582. 7. Oren M, Lorber B, Lee SH, et al. Anterior sacral meningocele: report of five cases and review of the literature. Dis Colon Rectum 1977;20:492–505. 8. Localio SA, Eng K, Ranson JHC. Abdominosacral approach for retrorectal tumors. Ann Surg 1980;191:555–560. 9. Hannon J, Subramony C, Scott-Conner CEH. Benign retrorectal tumors in adults: the choice of operative approach. Am Surg 1994;60:267–272.
Retrorectal cysts are a heterogeneous collection of lesions contained within the retrorectal space. The rarity of these tumors in adults and their nonspecific clinical presentations often lead to misdiagnoses. Patients frequently undergo multiple operations before the correct diagnosis is made. Several patients have been referred to the University of Illinois at Chicago and The Lahey Clinic Divisions of Colorectal Surgery for the treatment of previously misdiagnosed retrorectal cysts in recent
years. These cases are presented to illustrate several major clinical features. METHODS Medical records of the Divisions of Colorectal Surgery at the University of Illinois at Chicago and The Lahey Clinic were searched. Patients treated for retrorectal cysts were identified. From this group, patients with a referring diagnosis other than retrorectal cyst were identified. Patient demographics, referring diagnoses, diagnostic procedures, surgical history, and final pathology were collected.
No competing interests declared.
Supported in part by the Eleanor B Pillsbury Fellowship at the University of Illinois Hospital.
RESULTS The search identified seven patients. All seven had been treated at outside institutions before referral to either the University of Illinois at Chicago or the Lahey Clinic Divisions of Colorectal Surgery. There were six women and one man. Mean age was 36 years, with a range of 17 to 49 years. Presenting symptoms included lower back
Received May 29, 2002; Revised November 6, 2002; Accepted November 6, 2002. From the Departments of Surgery, The University of Illinois at Chicago, Chicago, IL (Singer, Cintron, Abcarian) and The Lahey Clinic, Burlington, MA (Martz, Schoetz). Correspondence address: Dr. Herand Abcarian, Department of Surgery, University of Illinois, 840 South Wood St, Room 518, M/C 958, Chicago, IL 60612.
© 2003 by the American College of Surgeons Published by Elsevier Science Inc.
880
ISSN 1072-7515/03/$21.00 doi:10.1016/S1072-7515(03)00133-9
Singer et al
Vol. 196, No. 6, June 2003
Misdiagnosed Retrorectal Cysts
881
Table 1. Patient Characteristics Pt. No. Age Gender (y)
Symptoms
Duration (y)
1
17
F
Back pain
1
2
18
F
4
3
44
F
Draining paracoccygeal sinus Rectal pain
4 5
33 45
F F
5 2
6
49
M
Rectal pain Pain; swelling; constipation; pain with ambulation Perianal pain; fevers
7
43
F
Draining wound
11
8
3
Previous treatments
Misdiagnoses
No. of procedures
Treatment
Final diagnosis
Drainage catheter ⫻ 2; I Perirectal abscess; ⫹ D; biopsy posttraumatic pain; 3 “pilonidal excisions”; Pilonidal CT fistulogram
5
Excision
Enteric cyst
5
Excision
Epidermoid cyst
I ⫹ D ⫻ 2; fistulogram; Presacral abscess, drainage catheter fistula in ano Colonoscopy ⫻ 3; Psychogenic pain CT myelogram; Pilonidal cyst aspiration of cyst ⫻ 2;
5
Excision
4 4
Excision Excision
Epidermoid cyst Hamartoma Hamartoma
Fistula in ano; I ⫹ D; I ⫹ D with perianal abscess excision fistula tract; I ⫹ D with fistulotomy; fistulectomy with malecot; curettage with catheter; sinogram with downsizing catheters Fistulectomy; closure Fistula in ano; internal and drainage perianal abscess
7
Excision with Hamartoma coccygectomy
3
Excision
Hamartoma
I ⫹ D, incision and draining.
pain, rectal or anal pain, constipation, swelling, pain with ambulation, fevers, and chronically draining wounds. The average duration of symptoms at presentation was 4.9 years, with a range of 1 to 11 years. Initial diagnoses included perianal abscess, fistula in ano, posttraumatic pain, pilonidal cyst, presacral abscess, postpartum pain, and psychogenic pain. The patients had undergone a mean of 4.7 operations or invasive procedures to diagnose and treat their disease (Table 1) excluding imaging studies. The correct diagnosis was made in all seven patients based on history, digital rectal examination, and CT scanning. All patients were treated with excision of the cyst by the posterior parasacrococcygeal approach. Only one patient required a coccygectomy during the excision. Final diagnoses included four hamartomas, two epidermoid cysts, and one enteric duplication cyst. A selected patient is presented below. It is representative of this patient group and illustrates several important features common to these patients. Case presentation
An 18-year-old woman complained of a persistently draining paracoccygeal sinus for 4 years. The drainage
was usually serosanguinous, and occasionally purulent. She also had intermittent fevers. She had previously undergone three operative resections for suspected pilonidal disease, with immediate recurrence of her symptoms after each operation. The patient was referred to our institution for evaluation of her persistent “pilonidal disease.” Examination revealed the external opening of a well epithelialized tract in the paracoccygeal region with serosanguinous drainage (Fig. 1). Rectal examination was unremarkable and showed no evidence of a primary fistulous opening. Laboratory tests were normal. A CT fistulogram of the abdomen and pelvis demonstrated a well-circumscribed 3 ⫻ 3-cm cystic mass in the retrorectal space (Fig. 2). There was no evidence of local invasion or bony destruction. Based on radiographic findings and the history of recurrent abscesses, a retrorectal cyst was diagnosed and the patient was taken to the operating room for excision of the cyst. The patient was operated on under spinal anesthesia and in the prone jack-knife position. A Foley catheter was introduced into the cyst through the sinus tract, and the catheter balloon was inflated with 5 mL of saline. A parasacrococcygeal incision was made. Levator ani mus-
882
Singer et al
Misdiagnosed Retrorectal Cysts
J Am Coll Surg
moid cyst. The patient did well postoperatively and has not had a recurrence of symptoms in more than 2 years.
Figure 1. Photograph of wound. Note the postanal dimple, which can be mistaken for a fistula in ano.
cles were divided and dissection continued into the supralevator space. The retrorectal space was then explored without removal of the coccyx. The cyst, which was well demarcated because of the inflated Foley catheter balloon, was carefully dissected off the posterior wall of the rectum. The excised cyst was then opened for examination (Fig. 3), and the diagnosis of an epidermoid developmental cyst was made. The muscle layers were reapproximated and the wound was closed over a suction drain. Pathology confirmed the diagnosis of an epider-
DISCUSSION The true incidence of retrorectal cysts is difficult to estimate because there have been few large series published. Jao and colleagues1 have estimated the incidence of retrorectal cysts to be approximately 1 in 40,000 hospital admissions to the Mayo Clinic. The etiology of the cysts is varied (Table 2). Because this list is extensive, a comprehensive review of each type will not be presented. Rather, the types of cysts in the case series will be briefly reviewed. About half of all retrorectal tumors are congenital lesions, and most of those are developmental cysts (epidermoid, dermoid, mucus-secreting cysts, and teratomas). Developmental cysts can arise from any of the germ layers. A strong female predominance is associated with developmental cysts.1 Both epidermoid and dermoid cysts result from closure defects of the ectodermal tube with inclusions of skin, but dermoid cysts also contain skin appendages, such as sweat glands, hair follicles, or sebaceous glands.1 The cysts can communicate with the skin surface, causing a characteristic postanal dimple. Approximately one-third will become infected.2 If an infected cyst communicates with a postanal dimple,
Figure 2. CT fistulogram. (Left) The patient in the prone position as contrast material is injected into the external opening and is obviously filling the cyst cavity. There is clearly no communication with the rectum. (Right) The patient in the supine position and lateral displacement of the rectum by the cyst.
Vol. 196, No. 6, June 2003
Singer et al
Misdiagnosed Retrorectal Cysts
883
Table 2. Differential Diagnosis of a Retrorectal Cyst Congenital Osseous Epidermoid Dermoid Mucus-secreting Teratoma Chordoma Teratocarcinoma Adrenal rest tumor Anterior sacral meningocele Duplication of rectum
Osteoma Osteogenic sarcoma Simple bone cyst, sacrum Ewing’s tumor Chondromyxosarcoma Aneurysmal bone cyst Giant cell tumor
Miscellaneous Inflammatory
Figure 3. Photograph of epidermoid cyst.
the appearance can be quite similar to a fistula in ano or pilonidal disease, resulting in misdiagnosis. Enterogenous cysts result from the sequestration of the developing hindgut. They tend to be multilocular, with one major cyst and several adjacent minor cysts. Like dermoid and epidermoid cysts, these are also more common in women and tend to become infected. If not infected or malignant, they will usually remain asymptomatic. They are almost always benign, although malignancy has been reported in the literature.3 Tailgut cysts (also called cystic hamartomas or mucus secreting cysts) are remnants of the embryonic portion of the gut extending beyond the anus. This portion of the gut normally regresses with the embryonic tail.4 They can be differentiated from dermoid cysts by the lack of dermal appendages, from enteric cysts by the lack of intestinal epithelium, and from teratomas that contain all three germ layers. Complete excision of the entire cyst will prevent recurrence. Benign lesions are more common than malignant lesions in most reported series.1,5,6 In adults, the risk of malignancy in cystic lesions of any type is somewhere between 10% and 60%.5 The most common retrorectal malignancy is the chordoma, which arises from remnants of the fetal notochord. Malignancy is equally common in men and women, despite the fact that retrorectal lesions are much more common in women. This might
Foreign body granuloma Perineal abscess Internal fistula Pelvirectal abscess Chronic infectious granuloma
Neurogenic Neurofibroma and sarcoma Neurilemoma Ependymoma Ganglioneuroma Neurofibrosarcoma
Metastatic carcinoma Liposarcoma Hemangioendothelial sarcoma Lymphangioma Extra-abdominal desmoid tumor Plasma cell myeloma Malignant neoplasm of unknown type Lipoma Fibroma Fibrosarcoma Leiomyoma Leiomyosarcoma Hemangioma Pericytoma Endothelioma
(From: Uhlig BE, Johnson RL. Presacral tumors and cysts in adults. Dis Colon Rectum 1975;18:581–596, with permission.)
relate to the fact that malignant tumors are usually symptomatic and will present themselves; benign tumors are usually asymptomatic and remain undetected until the childbearing years. The frequency of pelvic examinations during that time might account for the increased incidence in women. The clinical presentation of retrorectal cysts is often nonspecific or misleading. The most common symptom is pain, especially if the cyst is infected or malignant. The pain is typically vague, poorly localized, and dull. If the tumor has invaded the sacral plexus, then pain can be experienced in the legs or buttocks. The pain can be postural, especially with chordomas. Infection can be the presenting symptom in some patients. The appearance of a draining sinus or fistula tract is what frequently leads to misdiagnosis as pilonidal abscess, perianal abscess, or fistula in ano. A history of multiple drainage procedures and recurrences should be
884
Singer et al
Misdiagnosed Retrorectal Cysts
J Am Coll Surg
Figure 4. Fistulogram. The catheter has been inserted into the cutaneous wound. The contrast fills the cyst, but does not communicate with the rectum. Note the lobular appearance of the cyst.
a warning to the clinician that an undiagnosed retrorectal cyst exists. Large masses can cause constipation, and nerve invasion can result in fecal incontinence or urinary symptoms. A previously undiagnosed tumor can grow large enough to obstruct labor.7 Anterior sacral meningoceles can present as headache or recurrent meningitis.7 Physical examination is diagnostic in most cases and can also determine the operative approach for most patients. In the Mayo Clinic series, 97% of tumors were detectable by digital rectal examination alone.1 A retrorectal mass can be palpated through the posterior wall of the rectum but cystic lesions can be more difficult to detect. Sigmoidoscopy should be performed in all cases to rule out invasion of the rectal wall. An infected mass that is palpable in the posterior perineum can be misdiagnosed as a perirectal abscess or infected pilonidal cyst. A “pilonidal cyst” anterior to the coccyx should suggest an alternative diagnosis. A postanal dimple suggests the presence of a developmental cyst (Fig. 1). Laxity of the sphincters or anesthesia of the perineum signifies invasion of the sacral nerves. Plain x-rays can be valuable in diagnosing retrorectal tumors. Solid tumors are often seen compressing, invading, or displacing the sacrum on the x-ray. Invasion or bony destruction suggests malignancy.4 Anterior sacral meningoceles can have the pathognomonic scimitar sign caused by a unilateral sacral defect. Chronic fistulae can be evaluated with a fistulogram, which documents anatomy and rules out communication with the rectum (Fig. 4). CT scans have become the most valuable diagnostic
modality for evaluating retrorectal tumors. CT scans can determine if the lesion is cystic or solid, define the extent of the tumor and its relationship to surrounding structures, and help plan an operative approach (Fig. 2). MRI has been used with equal success in our experience, but published data are lacking. Myelography can help to confirm involvement of the central nervous system. Endorectal ultrasonography can be beneficial in evaluating retrorectal cysts.5 If a lesion is thought to be resectable, then there is no role for preoperative biopsy. Even benign lesions must be completely resected because there is an increased chance of becoming infected or malignant with time. In addition, needle biopsy puts the patient at risk for seeding of the tract with malignant cells, and at risk for meningitis if a meningocele is present. Only if a lesion is thought to be inoperable, can a biopsy be useful to determine adjuvant therapy. If a biopsy must be performed, then a CT-guided extrarectal and presacral approach is recommended.5 Transrectal biopsy should be avoided because of the risk of infection or seeding the rectum with tumor. Choices of operative approach include the abdominal approach, posterior approach, or a combined technique. The abdominal approach is best for high retrorectal tumors. If the tumor invades the rectum, resection would be required. The posterior approach is most useful for low-lying lesions and infected cysts. If superior border of the tumor can be palpated during digital examination, the posterior approach should be successful. The patient is
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Figure 5. Resection via posterior approach. The operation is performed with the patient in the prone jack-knife position, A. The location of the cyst between the presacral fascia and rectum is illustrated, B, and the parasacrococcygeal skin incision is shown on C. The anococcygeal ligament is divided transversely (arrow), and the gluteus maximus muscle can be partially divided to gain exposure, D. The cyst is readily identified and dissected sharply from the rectal wall and lateral attachments, E. (Adapted from Abel ME, Nelson R, Prasad ML, et al. Parasacrococcygeal approach for the resection of retrorectal development cysts. Dis Colon Rectum 1985;28:855– 858, with permission.)
placed in the prone jack-knife position. A parasacrococcygeal, curvilinear, or horizontal incision can be used. The anococcygeal ligament and the levator ani muscle are divided, and the supralevator space is entered. Some surgeons prefer to remove the coccyx routinely, but Abel and colleagues2 demonstrated that tumors can successfully be excised through the paracoccygeal approach without removing the coccyx (Fig. 5). If the tumor extends in the cephalad direction, hemostasis can be difficult. If hemorrhage is uncontrollable, then the patient should be repositioned and a laparotomy performed. Infected cysts should be drained, and then excised electively at a later time. Tumors greater than 3 or 4 cm or those rising above the sacral promontory might be best approached with a combined abdominosacral approach.8,9 This permits maximal vascular control and good exposure for protection of the sacral nerves. Laparotomy is performed first, followed by posterior dissection and resection. Mobilization of the rectum from above can make resolution of the mass from below a simpler procedure.5 Irrespective of the approach, all patients should un-
dergo preoperative mechanical and antibiotic preparation, in case the cyst connects with or tumor invades the rectum and partial rectal excision and closure is needed. Longterm survival after treatment of retrorectal cyst is difficult to estimate because of the wide variety of pathology comprising this category of tumor. At the Mayo Clinic, 5-year survival for chordoma was 75%, but only 17% for other malignancies.1 In cases of local recurrence, most reexcision should be attempted. Surgical exposure to the retrorectal space is limited at best, so complete excision at the first attempt is critical. Radiotherapy can provide palliation for some inoperable tumors. Chemotherapy has essentially no role at this time. Although small in number, this case series illustrates several important features of retrorectal cysts, ie, delay in diagnosis, misdiagnosis, and errors in treatment. Presence of postanal dimple, palpable mass, history of recurrent disease, lack of an infected anal gland, and fullness in the precoccygeal region should all suggest the presence of retrorectal cyst. CT scan (with or without fistulogram) is the diagnostic procedure of choice for retro-
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rectal cyst. Most patients can be managed through parasacrococcygeal approach without coccygectomy.2 In conclusion, retrorectal cyst is a rare entity that can be difficult to diagnose. Patients can be misdiagnosed and inappropriately treated for many years. Physical examination in combination with CT scanning will make the diagnosis in all patients. Complete surgical excision is required in all patients, and can usually be accomplished through the posterior approach. Author contributions
Study conception and design: Cintron, Schoetz, Abcarian Acquisition of data: Singer, Martz Analysis and interpretation of data: Singer, Cintron, Abcarian Drafting of manuscript: Singer Critical revision: Cintron, Abcarian Statistical expertise: Singer, Abcarian Supervision: Abcarian
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REFERENCES 1. Jao SW, Beart RW Jr, Spencer RJ, et al. Retrorectal tumors: Mayo Clinic Experience, 1960-1979. Dis Colon Rectum 1985;28:644– 652. 2. Abel ME, Nelson R, Prasad ML, et al. Parasacrococcygeal approach for the resection of retrorectal developmental cysts. Dis Colon Rectum 1985;28:855–858. 3. Springall RG, Griffiths JD. Malignant change in retrorectal duplication. J R Soc Med 1990;83:185–186. 4. Hjermstad BM, Helwig EB. Tailgut cysts. Report of 53 cases. Am J Clin Pathol 1988;89:139–147. 5. Gordon PH. Retrorectal tumors. In: Gordon PH, Nivatvongs S, eds. Principles and practice of surgery for the colon, rectum, and anus. 2nd ed. St Louis, MO: Quality Medical Publishing; 1999: 428–445. 6. Gray SW, Singhabhandhu B, Smith RA, et al. Sacrococcygeal chordoma: report of a case and review of the literature. Surgery 1975;78:573–582. 7. Oren M, Lorber B, Lee SH, et al. Anterior sacral meningocele: report of five cases and review of the literature. Dis Colon Rectum 1977;20:492–505. 8. Localio SA, Eng K, Ranson JHC. Abdominosacral approach for retrorectal tumors. Ann Surg 1980;191:555–560. 9. Hannon J, Subramony C, Scott-Conner CEH. Benign retrorectal tumors in adults: the choice of operative approach. Am Surg 1994;60:267–272.