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Rhabdomyomatous Mesenchymal Hamartoma: A Plaque-Type Variant in an Adult
Rhabdomyomatous mesenchymal hamartoma
RHABDOMYOMATOUS MESENCHYMAL HAMARTOMA: A PLAQUE-TYPE VARIANT IN AN ADULT Chih-Po Chang and Gwo-Shing Chen Department of Dermatology, Kaohsiung Medical University, Kaohsiung, Taiwan.
We present the case of a 40-year-old woman who had a flesh-colored asymptomatic plaque-like lesion above her chin since she was 30 years old. She was generally healthy and physical examination revealed no congenital abnormalities. Histopathology revealed a normal epidermal surface, mature striated muscle fibers arranged randomly within the dermis, and subcutaneous tissue associated with normal-appearing mesenchymal elements such as adipose tissue, collagen, blood vessels, and mature hair follicles. This fits the diagnosis of rhabdomyomatous mesenchymal hamartoma. Our case was different from previously reported cases with regards to the age of onset and clinical presentation. We report this rare adult case and discuss its differential diagnosis.
Key Words: rhabdomyomatous mesenchymal hamartoma, striated muscle, plaque (Kaohsiung J Med Sci 2005;21:185–8)
Rhabdomyomatous mesenchymal hamartoma (RMH) of the skin was first reported in English-language literature by Mills, who described a solitary dermal nodule in a newborn boy without congenital abnormalities [1]. Histologic features included normal epidermal surfaces and mature striated muscle fibers arranged randomly within the dermis associated with normal-appearing mesenchymal elements such as adipose tissue, collagen, and blood vessels. This kind of benign hamartoma had been reported under several different names, including striated muscle hamartoma [2, 3], congenital midline hamartoma [4], and hamartoma of the cutaneous adnexa and mesenchyme [5]. To the best of our knowledge, there are 24 cases in currently available English-language literature but only three case reports involving adults, males in each case [6,7]. No plaque-type lesions have been documented. Thus, we report an adult case and review the literature about this special hamartoma.
Received: November 25, 2004 Accepted: January 24, 2005 Address correspondence and reprint requests to: Dr. Gwo-Shing Chen, Department of Dermatology, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan. E-mail: [email protected] Kaohsiung J Med Sci April 2005 • Vol 21 • No 4 © 2005 Elsevier. All rights reserved.
CASE PRESENTATION This 40-year-old female came to our clinic to evaluate skincolored chin papules and plaques around the right mouth angle (Figure 1A). She stated that the skin lesion was not congenital, and it was only noted in her third decade. Physical examination revealed no pre-auricular skin tags or sinuses, vertebral abnormalities, or neurologic abnormalities. Family history was irrelevant. She only admitted a mild bumping sensation and cosmetic concerns. The lesion was not well demonstrated unless observed closely from the right lateral view (Figure 1B). Our first impression was some type of focal cutaneous mucinosis or mesenchymal tumor. Histopathologic findings revealed a normal epidermis and numerous bundles of mature skeletal muscle fibers randomly arranged in groups or randomly intermingled with collagen, blood vessels, and adipose tissue in the dermis and subcutis. Several mature pilosebaceous units were also present (Figure 2). A closer view showed cross striations with normal hematoxylin–eosin stain (Figure 3). These findings were consistent with the diagnosis of RMH. Since there is no report of treatment for a plaquetype RMH lesion, we encouraged our patient to undergo carbon dioxide laser treatment, but she was hesitant after receiving an explanation of its possible complications. 185
C.P. Chang and G.S. Chen Figure 1. (A) Clinical photograph revealing a smooth-topped, flesh-colored, plaque-like induration over the right upper chin (arrows). (B) Right lateral close-up view shows some papular lesions and confluent plaque (arrows).
A
B
➞ Figure 2. Photomicrograph shows predominance of mature skeletal muscle fibers (arrows) arranged randomly in the mingled collagen bundles, pilosebaceous units (P), and adipose tissue (*). (Hematoxylin & eosin, original magnification × 100.)
Figure 3. Higher magnification reveals the cross-striation muscle bundle distribution in the dermis and subcutis (arrow). (Hematoxylin & eosin, original magnification × 400.)
DISCUSSION
pre-auricular areas [1,9,10]. Most had lesions described as pedunculated papules resembling skin tags from birth. Reported locations include the sternal notch, periorbital area (eyelid, eyebrow), neck, nasal ala, nostril, forehead, and perineum. Two of the three adult cases had nasal papular lesions and the other presented with a subcutaneous nodule on his forehead, but none had plaque-type lesions. RMH is sometimes associated with other congenital abnormalities. At least four cases have been reported: a neonate with cleft lip and palate, amniotic bands, and syndactyl upper extremity digits [2]; a 6-month-old infant with coloboma, corneal leukoma, microphthalmia, and limbal dermoid [8]; a neonate with bilateral leukocoria from sclerocornea, low-set
RMHs have been reported as a benign single polypoid or sessile nodule/mass, and firm, fleshy skin lesions characterized histopathologically by randomly oriented mature striated muscle bundles and single muscle fibers within the dermis mingled with multiple mesenchymal tissue (collagen, adipose tissue, blood vessels) [8]. It was originally described as a striated muscle hamartoma by Hendrick et al [2] and subsequently renamed RMH by Mills [1]. All reports show male predominance. RMH is most common in AfricanAmericans and least common in Asians. Among reported cases, only two had multiple lesions on the periorbital and 186
Kaohsiung J Med Sci April 2005 • Vol 21 • No 4
Rhabdomyomatous mesenchymal hamartoma
ears, and pre-auricular sinus [9]; and a 3.5-month-old female with thyroglossal duct sinus [7]. The etiology of RMH is still unclear. It has been postulated that skeletal muscle fibers could aberrantly migrate into the dermis during embryogenesis [11]. Disturbances at 30–45 days of gestation, when branchial arches develop and populations of neural crest cells migrate, may impede the development of adjacent medial or frontonasal processes and have been suggested as possible causes of various anomaly syndromes with RMH [12]. Thus, it is suggested that RMH develops in anatomic areas containing second branchial arch-derived, superficially located, striated muscle, such as the orbicularis oris, platysma, and orbicularis oculi. RMH may also occur within the setting of multiple ectodermal/mesodermal abnormalities, suggested by the frequent occurrence of RMH in the setting of ocular abnormalities [8]. Several other clinical or pathologic entities must be considered in the differential diagnosis of RMH, including soft fibroma, nasal glioma, accessory tragus, nevus lipomatosus superficialis, neuromuscular hamartoma, fibrous hamartoma of infancy, and adult, fetal, and genital rhabdomyomas [13]. Soft fibroma can easily be excluded on microscopic grounds because it has an orderly arrangement of pilosebaceous and eccrine units with random mixtures of skeletal muscles [14]. Nasal glioma has central facial distribution and is typically located at the nasal root. Glial tissue can be seen on histopathology in nasal glioma, but never in RMH. Accessory tragus has elastic cartilage content along with eccrine sweat glands, blood vessels, and adipose tissue. Fragments of skeletal muscle may be present but are not a prominent feature. Clinically, accessory tragus would be more laterally distributed than RMH. Nevus lipomatosus superficialis exhibits ectopic adipose cell clusters in the upper dermis without a skeletal muscle component. Neuromuscular hamartoma (triton tumors) are composed of admixed skeletal muscle and neural elements (myelinated and unmyelinated nerve fibers) that can be demonstrated by S-100 staining, which is negative in RMH [14]. Infant fibrous hamartoma can be differentiated from RMH by the absence of skeletal muscle [9]. Adult rhabdomyomas are most commonly seen in the head and neck region of older people (age > 40 years). Histopathologically, they are composed of tightly packed, large, round or polygonal cells separated by thin fibrous septa and narrow vascular channels. Cross-striations are usually present but may be difficult to demonstrate [12]. Fetal rhabdomyoma, a rare benign tumor of infancy, also occurs in the Kaohsiung J Med Sci April 2005 • Vol 21 • No 4
head and neck region. It originates in subcutaneous tissue with myxoid matrix containing mesenchymal cells mixed in with scattered spindle cells showing varying degrees of skeletal differentiation without mature skeletal muscle bundles. Genital rhabdomyoma occurs as a mass in the vagina or vulva in young and middle-aged women. Scattered, predominantly mature, muscle fibers with distinct cross-striations are present in a matrix of varying amounts of collagen and mucoid material [8]. Our case corresponded to the diagnosis of RMH and the plaque-type lesion was unique. Although our patient had no clinically observable abnormality, we recommend systematic evaluation of patients diagnosed with this entity.
REFERENCES 1. Mills AE. Rhabdomyomatous mesenchymal hamartoma of skin. Am J Dermatopathol 1977;11:58–63. 2. Hendrick SJ, Sanchez RL, Blackwell SJ, et al. Striated muscle hamartoma: description of two cases. Pediatr Dermatol 1986;3: 153–7. 3. Nakanishi H, Hashimoto I, Takiwaki H, et al. Striated muscle hamartoma of the nostril. J Dermatol 1995;22:504–7. 4. Elgart GW, Patterson JW. Congential midline hamartoma: case report with histochemical and immunohistochemical findings. Pediatr Dermatol 1990;7:199–201. 5. Grilli R, Escalonilla P, Soriano ML, et al. The so-called striated muscle hamartoma is a hamartoma of cutaneous adnexa and mesenchyme, but not of striated muscle. Acta Derm Venereol 1998;78:390. 6. Rosenberg AS, Kirk J, Morgan MB, et al. Rhabdomyomatous mesenchymal hamartoma: an unusual dermal entity with a report of two cases and a review of the literature. J Cutan Pathol 2002;29:238–43. 7. Sanchez RL, Raimer SS. Clinical and histologic features of striated muscle hamartoma: possible relationship to Delleman’s syndrome. J Cutan Pathol 1994;21:40–6. 8. Read RW, Burnstine M, Rowland JM, et al. Rhabdomyomatous mesenchymal hamartoma of the eyelid: report of a case and literature review. Ophthalmology 2001;108:798–804. 9. Sahn EE, Garen PD, Pai GS, et al. Multiple rhabdomyomatous mesenchymal hamartomas of skin. Am J Dermatopathol 1990; 12:485–91. 10. Levkoff AH, Maize JC, Feingold M. Picture of the month. Am J Dis Child 1989;143:963–4. 11. Ashfaq R, Timmons CF. Rhabdomyomatous mesenchymal hamartoma of skin. Pediatr Pathol 1992;12:731–5. 12. Gorlin RJ, Cohen MM Jr, Levin LS. Syndromes of the Head and Neck, 3rd edition. New York: Oxford University Press, 1990:641–9. 13. Enzinger FM, Weiss SW. Soft Tissue Tumors, 3 rd edition. St. Louis: Mosby, 1995:523–37. 14. Markel SF, Enzinger FM. Neuromuscular hamartoma—a benign “triton tumor” composed of mature neural and striated muscle elements. Cancer 1982;49:140–4.
187
C.P. Chang and G.S. Chen
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!"VP NN OR !"VQ N OQ !"#$%&' !"!#$% UMT ! NMM Kaohsiung J Med Sci April 2005 • Vol 21 • No 4
RHABDOMYOMATOUS MESENCHYMAL HAMARTOMA: A PLAQUE-TYPE VARIANT IN AN ADULT Chih-Po Chang and Gwo-Shing Chen Department of Dermatology, Kaohsiung Medical University, Kaohsiung, Taiwan.
We present the case of a 40-year-old woman who had a flesh-colored asymptomatic plaque-like lesion above her chin since she was 30 years old. She was generally healthy and physical examination revealed no congenital abnormalities. Histopathology revealed a normal epidermal surface, mature striated muscle fibers arranged randomly within the dermis, and subcutaneous tissue associated with normal-appearing mesenchymal elements such as adipose tissue, collagen, blood vessels, and mature hair follicles. This fits the diagnosis of rhabdomyomatous mesenchymal hamartoma. Our case was different from previously reported cases with regards to the age of onset and clinical presentation. We report this rare adult case and discuss its differential diagnosis.
Key Words: rhabdomyomatous mesenchymal hamartoma, striated muscle, plaque (Kaohsiung J Med Sci 2005;21:185–8)
Rhabdomyomatous mesenchymal hamartoma (RMH) of the skin was first reported in English-language literature by Mills, who described a solitary dermal nodule in a newborn boy without congenital abnormalities [1]. Histologic features included normal epidermal surfaces and mature striated muscle fibers arranged randomly within the dermis associated with normal-appearing mesenchymal elements such as adipose tissue, collagen, and blood vessels. This kind of benign hamartoma had been reported under several different names, including striated muscle hamartoma [2, 3], congenital midline hamartoma [4], and hamartoma of the cutaneous adnexa and mesenchyme [5]. To the best of our knowledge, there are 24 cases in currently available English-language literature but only three case reports involving adults, males in each case [6,7]. No plaque-type lesions have been documented. Thus, we report an adult case and review the literature about this special hamartoma.
Received: November 25, 2004 Accepted: January 24, 2005 Address correspondence and reprint requests to: Dr. Gwo-Shing Chen, Department of Dermatology, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan. E-mail: [email protected] Kaohsiung J Med Sci April 2005 • Vol 21 • No 4 © 2005 Elsevier. All rights reserved.
CASE PRESENTATION This 40-year-old female came to our clinic to evaluate skincolored chin papules and plaques around the right mouth angle (Figure 1A). She stated that the skin lesion was not congenital, and it was only noted in her third decade. Physical examination revealed no pre-auricular skin tags or sinuses, vertebral abnormalities, or neurologic abnormalities. Family history was irrelevant. She only admitted a mild bumping sensation and cosmetic concerns. The lesion was not well demonstrated unless observed closely from the right lateral view (Figure 1B). Our first impression was some type of focal cutaneous mucinosis or mesenchymal tumor. Histopathologic findings revealed a normal epidermis and numerous bundles of mature skeletal muscle fibers randomly arranged in groups or randomly intermingled with collagen, blood vessels, and adipose tissue in the dermis and subcutis. Several mature pilosebaceous units were also present (Figure 2). A closer view showed cross striations with normal hematoxylin–eosin stain (Figure 3). These findings were consistent with the diagnosis of RMH. Since there is no report of treatment for a plaquetype RMH lesion, we encouraged our patient to undergo carbon dioxide laser treatment, but she was hesitant after receiving an explanation of its possible complications. 185
C.P. Chang and G.S. Chen Figure 1. (A) Clinical photograph revealing a smooth-topped, flesh-colored, plaque-like induration over the right upper chin (arrows). (B) Right lateral close-up view shows some papular lesions and confluent plaque (arrows).
A
B
➞ Figure 2. Photomicrograph shows predominance of mature skeletal muscle fibers (arrows) arranged randomly in the mingled collagen bundles, pilosebaceous units (P), and adipose tissue (*). (Hematoxylin & eosin, original magnification × 100.)
Figure 3. Higher magnification reveals the cross-striation muscle bundle distribution in the dermis and subcutis (arrow). (Hematoxylin & eosin, original magnification × 400.)
DISCUSSION
pre-auricular areas [1,9,10]. Most had lesions described as pedunculated papules resembling skin tags from birth. Reported locations include the sternal notch, periorbital area (eyelid, eyebrow), neck, nasal ala, nostril, forehead, and perineum. Two of the three adult cases had nasal papular lesions and the other presented with a subcutaneous nodule on his forehead, but none had plaque-type lesions. RMH is sometimes associated with other congenital abnormalities. At least four cases have been reported: a neonate with cleft lip and palate, amniotic bands, and syndactyl upper extremity digits [2]; a 6-month-old infant with coloboma, corneal leukoma, microphthalmia, and limbal dermoid [8]; a neonate with bilateral leukocoria from sclerocornea, low-set
RMHs have been reported as a benign single polypoid or sessile nodule/mass, and firm, fleshy skin lesions characterized histopathologically by randomly oriented mature striated muscle bundles and single muscle fibers within the dermis mingled with multiple mesenchymal tissue (collagen, adipose tissue, blood vessels) [8]. It was originally described as a striated muscle hamartoma by Hendrick et al [2] and subsequently renamed RMH by Mills [1]. All reports show male predominance. RMH is most common in AfricanAmericans and least common in Asians. Among reported cases, only two had multiple lesions on the periorbital and 186
Kaohsiung J Med Sci April 2005 • Vol 21 • No 4
Rhabdomyomatous mesenchymal hamartoma
ears, and pre-auricular sinus [9]; and a 3.5-month-old female with thyroglossal duct sinus [7]. The etiology of RMH is still unclear. It has been postulated that skeletal muscle fibers could aberrantly migrate into the dermis during embryogenesis [11]. Disturbances at 30–45 days of gestation, when branchial arches develop and populations of neural crest cells migrate, may impede the development of adjacent medial or frontonasal processes and have been suggested as possible causes of various anomaly syndromes with RMH [12]. Thus, it is suggested that RMH develops in anatomic areas containing second branchial arch-derived, superficially located, striated muscle, such as the orbicularis oris, platysma, and orbicularis oculi. RMH may also occur within the setting of multiple ectodermal/mesodermal abnormalities, suggested by the frequent occurrence of RMH in the setting of ocular abnormalities [8]. Several other clinical or pathologic entities must be considered in the differential diagnosis of RMH, including soft fibroma, nasal glioma, accessory tragus, nevus lipomatosus superficialis, neuromuscular hamartoma, fibrous hamartoma of infancy, and adult, fetal, and genital rhabdomyomas [13]. Soft fibroma can easily be excluded on microscopic grounds because it has an orderly arrangement of pilosebaceous and eccrine units with random mixtures of skeletal muscles [14]. Nasal glioma has central facial distribution and is typically located at the nasal root. Glial tissue can be seen on histopathology in nasal glioma, but never in RMH. Accessory tragus has elastic cartilage content along with eccrine sweat glands, blood vessels, and adipose tissue. Fragments of skeletal muscle may be present but are not a prominent feature. Clinically, accessory tragus would be more laterally distributed than RMH. Nevus lipomatosus superficialis exhibits ectopic adipose cell clusters in the upper dermis without a skeletal muscle component. Neuromuscular hamartoma (triton tumors) are composed of admixed skeletal muscle and neural elements (myelinated and unmyelinated nerve fibers) that can be demonstrated by S-100 staining, which is negative in RMH [14]. Infant fibrous hamartoma can be differentiated from RMH by the absence of skeletal muscle [9]. Adult rhabdomyomas are most commonly seen in the head and neck region of older people (age > 40 years). Histopathologically, they are composed of tightly packed, large, round or polygonal cells separated by thin fibrous septa and narrow vascular channels. Cross-striations are usually present but may be difficult to demonstrate [12]. Fetal rhabdomyoma, a rare benign tumor of infancy, also occurs in the Kaohsiung J Med Sci April 2005 • Vol 21 • No 4
head and neck region. It originates in subcutaneous tissue with myxoid matrix containing mesenchymal cells mixed in with scattered spindle cells showing varying degrees of skeletal differentiation without mature skeletal muscle bundles. Genital rhabdomyoma occurs as a mass in the vagina or vulva in young and middle-aged women. Scattered, predominantly mature, muscle fibers with distinct cross-striations are present in a matrix of varying amounts of collagen and mucoid material [8]. Our case corresponded to the diagnosis of RMH and the plaque-type lesion was unique. Although our patient had no clinically observable abnormality, we recommend systematic evaluation of patients diagnosed with this entity.
REFERENCES 1. Mills AE. Rhabdomyomatous mesenchymal hamartoma of skin. Am J Dermatopathol 1977;11:58–63. 2. Hendrick SJ, Sanchez RL, Blackwell SJ, et al. Striated muscle hamartoma: description of two cases. Pediatr Dermatol 1986;3: 153–7. 3. Nakanishi H, Hashimoto I, Takiwaki H, et al. Striated muscle hamartoma of the nostril. J Dermatol 1995;22:504–7. 4. Elgart GW, Patterson JW. Congential midline hamartoma: case report with histochemical and immunohistochemical findings. Pediatr Dermatol 1990;7:199–201. 5. Grilli R, Escalonilla P, Soriano ML, et al. The so-called striated muscle hamartoma is a hamartoma of cutaneous adnexa and mesenchyme, but not of striated muscle. Acta Derm Venereol 1998;78:390. 6. Rosenberg AS, Kirk J, Morgan MB, et al. Rhabdomyomatous mesenchymal hamartoma: an unusual dermal entity with a report of two cases and a review of the literature. J Cutan Pathol 2002;29:238–43. 7. Sanchez RL, Raimer SS. Clinical and histologic features of striated muscle hamartoma: possible relationship to Delleman’s syndrome. J Cutan Pathol 1994;21:40–6. 8. Read RW, Burnstine M, Rowland JM, et al. Rhabdomyomatous mesenchymal hamartoma of the eyelid: report of a case and literature review. Ophthalmology 2001;108:798–804. 9. Sahn EE, Garen PD, Pai GS, et al. Multiple rhabdomyomatous mesenchymal hamartomas of skin. Am J Dermatopathol 1990; 12:485–91. 10. Levkoff AH, Maize JC, Feingold M. Picture of the month. Am J Dis Child 1989;143:963–4. 11. Ashfaq R, Timmons CF. Rhabdomyomatous mesenchymal hamartoma of skin. Pediatr Pathol 1992;12:731–5. 12. Gorlin RJ, Cohen MM Jr, Levin LS. Syndromes of the Head and Neck, 3rd edition. New York: Oxford University Press, 1990:641–9. 13. Enzinger FM, Weiss SW. Soft Tissue Tumors, 3 rd edition. St. Louis: Mosby, 1995:523–37. 14. Markel SF, Enzinger FM. Neuromuscular hamartoma—a benign “triton tumor” composed of mature neural and striated muscle elements. Cancer 1982;49:140–4.
187
C.P. Chang and G.S. Chen
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