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Rhabdomyomatous Mesenchymal Hamartoma Associated with Congenital Anomalies: Report of an Unusual Perineal Case

Jia-Ru Wang Tseng-Tong Kuo1 Ke-Jen Yu Po-Yu Shih Yue-Zon Kuan Chih-Hsun Yang2

The ectopic occurrence of skeletal muscles in skin is an unusual condition. These lesions are named rhabdomyomatous mesenchymal hamartoma now. More accurately speaking, this entity should be called “cutaneous rhabdomyomatous choristoma” because the skeletal muscle is not a normal element in skin. We described a case occurring in perineal region associated with amniotic band syndrome, imperforate anus, and intestinal atresia. The association with gastro-intestinal tract anomaly has not been reported previously. This unusual case is documented and compared to two other cases reported in this region. (Dermatol Sinica 26: 93-98, 2008)

Key words: Rhabdomyomatous, Hamartoma, Choristoma

Case Report

INTRODUCTIONThe ectopic occurrence of skeletal mus-

cles in skin is an unusual condition. Thirty-three cases have been reported in the literature under various names of hamartoma. We saw a case occurring in perineal region. This unusual case is documented and compared to two other reported cases occurring in perineal region.

CASE REPORT

A full-term Taiwanese male baby was born to a G2P2 mother with normal birth weight (3850 gm). Regular antepartum ex-aminations were uneventful and did not reveal any abnormalities. She denied any invasive antepartum procedures, including amniocente-sis. Multiple congenital anomalies, including high type imperforate anus with recto-bulbar urethral fistula, atresia of large intestine and rectum, hypospadia, scrotal bifida with severe chordee, and anomalies of the right big and

little toes (amniotic band syndrome), were noted at birth. Multiple irregular, confluent hy-popigmented macules and plaques and several small satellite lesions were found in the lower part of the scrotum, peri-anal area left to the imperforate anal dimple, and bilateral coccy-geal regions (Fig. 1). The clinical differential diagnosis included nevus anemicus, nevus de-pigmentosa, segmental vitiligo and lichen scle-rosis et atrophicus. A skin biopsy specimen, which was taken from the skin 2 cm away from the left side of the imperforate anal dim-ple, revealed mild acanthosis with decreased pigmentation of the basal layer and multiple skeletal muscle fibers in dermis and subcutis (Fig. 2A). Cross striations were evident in these skeletal muscle fibers (Fig. 2B). Pilose-baceous structures and sweat glands appeared to be normal. There were loose fibrous bands in subcutis and the fat cells showed variation in sizes (Fig. 2C). Immunostaining for HHF-

From the Departments of Dermatology and Pathology1, Chang Gung Memorial Hospital and Chang Gung University, Kwei-Shan Tao-Yuan, Taiwan2

Accepted for publication: January 24, 2008Reprint requests: Yue-Zon Kuan, MD, Department of Dermatology, Chang Gung Memorial HospitalTEL: 886-935510945 , 886-968375439 FAX: 886-2-27191623 E-mail:jiaru@adm.cgmh.org.tw

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35 (muscle actin antibody, Dako, Denmark), MyoD1 (Myogenin D1, Dako, Denmark) and Desmin (Dako, Denmark) confirmed the ec-topic presence of striated muscle fibers (Fig. 2D).

Ultrasonographic examination of the brain via the anterior fontanel revealed normal midline structure, including corpus callosum. Chromosome study demonstrated normal karyotype (46, XY). Trisomy was therefore excluded. Atresia of large intestine and rec-tum, imperforate anus, hypospadia and scrotal bifida were corrected in sequential surgeries. Hirschsprung’s disease, a possible etiology of intestinal atresia, was excluded due to the presence of ganglion cells in the anorectal tis-sue. The infant was physically well at age of 5 months old.

DISCUSSIONBy definition, hamartomas are benign tu-

mor-like nodules composed of overgrowths of mature cells and tissues, but with disorganiza-tion and often with one predominant element. In the skin, aberrant proliferations of several cellular lineages, including smooth muscle, sweat glandular, pilar, fibroelastic, vascular, neural, and melanocytic elements can occur.

Choristoma is defined as a mass formed by the faulty development of tissue not normally found at that site.

The pathologic characteristics of the present case are the same with the findings of the reported cases of rhabdomyomatous mes-enchymal hamartomas. The entity was first de-scribed in 1986 by Hendrick et al.1 as “striated muscle hamartoma” and subsequently renamed “rhabdomyomatous mesenchymal hamartoma” 2 (RMH) or “congenital midline hamartoma”.3 More accurately speaking, this entity should be called “cutaneous rhabdomyomatous cho-ristoma”, because the skeletal muscle is not a normal element in skin. The clinical manifesta-tions are variable, including pedunculated pol-yps, subcutaneous nodules, or sessile masses and papules. To our knowledge, there are only 33 reported cases in the English language lit-erature. 1-9,11-14 Of these, there is a 1.35:1 male-to-female preponderance.1-9,11-14 It occurs most commonly in the head and neck regions where striated muscles, such as the orbicularis oris, platysma, orbicularis oculi, are superficially located, suggesting aberrant embryonic migra-tion of striated muscle fibers into the dermis as a possible etiology.9

Including the present patient, only 3 cases occurring in the perineal regions have been reported. (Table 1) The anal canal, like the head and neck, is adjacent to developing skeletal muscles during embryogenesis,10 al-lowing potentially aberrant migration of rhab-domyogenic elements into superficial locations during development. The first report of a lesion arising in perianal region was in a 7-month-old girl associated with a hemangioma in the same area that later regressed completely.11 The sec-ond patient, a 3-month-old girl, presented with a polypoid lesion in which disorganized arrays of skeletal muscle fibers with admixed adipose tissue and smooth muscles in dermis.8 No other congenital anomaly was mentioned in either case.

Rhabdomyomatous mesenchymal hama-

Fig. 1 Multiple irregular, confluent hypopigmented macule and several small satellite lesions in the lower part of the scro-tum, peri-anal area left to the imperforate anal dimple, and bilateral coccygeal regions.

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rtoma may present sporadically as a solitary lesion in a normal neonate as in the majority of cases or can be associated with multiple congenital anomalies, including amniotic band syndrome,1 ocular abnormalities, thyroglossal duct sinus11 and Delleman’s syndrome.12 Del-leman’s syndrome consists of colobomas, an absent corpus callosum, orbital cysts, proen-cephalic cysts, and facial skin tags. The normal midline structure, including corpus callosum, and the absence of facial skin tags in the pres-ent case exclude the possibility of Delleman’s syndrome.

The amniotic band syndrome is a col-

lection of fetal malformations associated with fibrous bands that appear to entangle or entrap various fetal parts in utero, leading to deforma-tion, malformation, or disruption.15 The etiolo-gy is unknown. Hendrick et al.1 postulated that traction on the skin by amniotic adhesions may predispose toward the development of a rhab-domyomatous mesenchymal hamartoma. There have also been reports associating amniotic band syndrome with amniocentesis.16 However, the mother of our patient did not recieve am-niocentesis during antepartum examination.

In addition to amniotic band syndrome, our patient also had imperforate anus, intesti-

Fig. 2 (A) Decreased pigmentation of the basal layer and horizontally oriented skeletal muscle fibers in dermis.(B) Higher magnification to show skeletal muscle fibers with cross striations. (C) The fat cells showed variation in sizes with increased vascularity. Skeletal muscle immunopositive to anti-desmin anti-body. (A, B and C, Hematoxylin-eosin stain; original magnifications: A, x100; B, x400; C, x200; D, desmin; original magnifica-tions: x400)

A. B.

C D

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nal atresia, hypospadia, and scrotal bifida with severe chordee. Anorectal malformations occur in 1 in 4000 to 1 in 5000 newborns17 and are more common among males and in children with Down syndrome (Trisomy 21). Anal mal-formations are believed to result from failure of migration of the anus and excessive fusion. The higher and more complex the anorectal malforamtions, the greater the chance of a life-threatening defect, especially a urologic anomaly.18 Urogenital defects, such as hypos-padias, vesicoureteral reflux, cryptoorchidism, rotated kidney, neurogenic bladder and renal agenesis occur in 48% of patients with anorec-tal malformations.18 Atresia of large intestine and rectum, imperforate anus with recto-bulbar urethral fistula, hypospadia and scrotal bifida were corrected in sequential operations by pediatric surgeons in the present case. The as-sociation of rhabdomyomatous mesenchymal hamartoma with gastrointestinal tract anomaly has not been documented previously. The etio-pathogenesis of potentially aberrant migration in embryogenesis in both entities might explain the combination of the above mentioned pre-sentations.

In summary, we report a male neonate presenting with rhabdomyomatous mesenchy-

mal hamartoma of the perineal region associ-ated with amniotic band syndrome, imperforate anus and intestinal atresia. The association with gastrointestinal and genitourinary tract anoma-lies has not been reported previously. Although rhabdomyomatous mesenchymal hamartoma may present as a solitary lesion in a neonate in most cases, systemic evaluation for other congenital anomalies is warranted because of possible common etiologies.

REFERENCES1. Hendrick SJ, Sanchez RL, Blackwell SJ, et al.:

Striated muscle hamartoma: description of two cases. Pediatr Dermatol 3: 153-157, 1986.

2. Mills AE: Rhabdomyomatous mesenchymal hama-rtoma of skin. Am J Dermatopathol 11: 58-63, 1989.

3. Elgart GW, Patterson JW: Congenital midline hamartoma: case report with histochemical and im-munohistochemical findings. Pediatr Dermatol 7: 199-201, 1990.

4. Read RW, Burnstine M, Rowland JM, et al.: Rhab-domyomatous mesenchymal hamartoma of the eyelid. Ophthalmol 108: 798-804, 2001.

5. Rosenberg AS, Kirk J, Morgan MB: Rhabdomyo-matous mesenchymal hamartoma: an unusual der-mal entity with a report of two cases and a review of the literature. J Cutan Pathol 29: 238-243, 2002.

6. Takeyama J, Hayashi T, Sanada T, et al.: Rhab-domyomatous mesenchymal hamartoma associated with nasofrontal meningocele and dermoid cyst. J

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Cutan Pathol 32: 310-313, 2005.7. Chang CP, Chen GS: Rhabdomyomatous mesen-

chymal hamartoma: a plaque-type variant in an adult. Kaohsiung J Med Sci 21: 185-188, 2005.

8. Schrecengost JE, Tabbara S, Patterson J, et al.: Cutaneous mesenchymal hamartoma with mixed myogenous differentiation. J Cutan Pathol 33: 327-330, 2006.

9. Ashfaq R, Timmons CF: Rhabdomyomatous mes-enchymal hamartoma of skin. Pediatr Pathol 12: 731-735, 1992.

10. Frober R, Krebs U, Haas A, et al.: Three-dimen-sional reconstruction of the anal striated muscula-ture in a human fetus. Cells Tissues Organs 169: 152-157, 2001.

11. Scrivener Y, Petiau P, Rodier-Bruant C, et al.: Pe-rianal striated muscle hamartoma associated with hemangioma. Pediatr Dermatol 15: 274-276, 1998.

12. Sanchez RL, Raimer SS: Clinical and histologic features of striated muscle hamartoma: possible re-lationship to Delleman’s syndrome. J Cutan Pathol 21: 40-46, 1994.

13. Solis-Coria A, Vargas-González R, Sotelo-Avila C:

Rhabdomyomatous mesenchymal hamartoma pre-senting as a skin tag in the sternoclavicular area. Pathol Oncol Res 13: 375-378, 2007.

14. Kim HS, Kim YJ, Kim JW, et al.: Rhabdomyoma-tous mesenchymal hamartoma. J Eur Acad Derma-tol Venereol 21: 564-565, 2007.

15. Seeds JW, Cefalo RC, Herbert WN: Amniotic band syndrome. Am J Obstet Gynecol 144: 243-248, 1982.

16. Lage JM, VanMarter LJ, Bieber FR: Questionable role of amniocentesis in the etiology of amniotic band formation. A case report. J Reprod Med 33: 71-73, 1988.

17. Trusler GA, Wilkinson RH: Imperforate anus: A review of 147 cases. Can J Surg 5: 269-277, 1962.

18. Kaha E, Daum F: Anatomy, histology, embryol-ogy, and developmental anomalies of the small and large intestine. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran’s gastro-intestinal and liver disease. 8th ed. Philadelphia: Saunders Elsevier; 2079-2083, 2006.

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橫紋肌間葉型錯構瘤伴隨先天異常：一個罕見的會

陰部病例報告

王佳茹　郭承統1　游可任　石博宇　官裕宗　楊志勛

2

臺北長庚醫院皮膚科 病理科1　長庚醫學大學醫學系

2

橫紋肌異常的在皮膚出現是一個稀有的狀況。這樣的病灶目前被命名為橫紋肌間葉型錯

構瘤，但因為橫紋肌並不屬於正常皮膚的成分，更正確的來說，他應該被命名為皮膚橫紋肌

迷離瘤。我們提出一個發生在會陰部的病例，他同時合併了羊水帶症候群、無肛症及腸道閉

鎖。伴隨著先天性腸胃道異常的情況以往並未曾被報告過。我們報告一個罕見的病例並且和

另外兩個發生在會陰部的病例作比較。（中華皮誌：26: 93-98, 2008）