[519] Primary Cutaneous Rhabdomyosarcoma: A Clinicopathologic Review of 11 Cases

Trent B Marburger, Jerad M Gardner, Victor G Prieto, Steven D Billings. Cleveland Clinic, Cleveland, OH; Emory University Hospital, Atlanta, GA; MD Anderson Cancer Center, Houston, TX

Background: Rhabdomyosarcoma (RMS) is a sarcoma with skeletal myogenic differentiation that is most often found in the head and neck, genitourinary tract, or deep soft tissue. Primary cutaneous RMS is extremely rare with < 20 documented cases in the English literature, only 5 of which presented in adults.
Design: Cases diagnosed as RMS were retrieved from the archives and consultation files of 3 institutions. For inclusion, cases had to arise in the dermis/subcutis with no evidence of a metastatic origin. Cases were subclassified as embryonal, alveolar, pleomorphic, and not otherwise specified (NOS) RMS. Clinicopathologic features were retrospectively reviewed.
Results: 11 cases met selection criteria. The tumors occurred in a bimodal age distribution including 5 pediatric patients (4M;1F, mean age 10 yrs, range 0.25-17 yrs) and 6 adults (4M;2F, mean age 74 yrs, range 60-87 yrs). The lesions involved the head and neck (6 cases), the extremities (4 cases), and the trunk (1 case). The adult subset consisted of pleomorphic (4 cases) and NOS (2 cases) subtypes while the pediatric subset demonstrated alveolar (1 case), embryonal (2 cases), and NOS (2 cases) subtypes. Immunohistochemical staining for desmin was positive in 10/10. For skeletal specific markers, MYOD1 was positive in 4/4 and myogenin in 7/8. The one myogenin negative case was a pleomorphic RMS that was positive for MYOD1. Three cases in the adult subset (2 NOS, 1 pleomorphic) demonstrated varying degrees of positive staining for cytokeratins, with one case strongly positive. Follow-up information was available on 3 cases. Two pediatric cases with follow-up demonstrated recurrence (embryonal at 20 months, alveolar at 14 months) and ultimately died of disease after 9 years and 3 years, respectively. A single adult patient with pleomorphic RMS was ANED after 1 year.
Conclusions: Primary cutaneous RMS demonstrates a distinctly bimodal age distribution that correlates with RMS in other settings. Cutaneous embryonal and alveolar RMS were more common in children, while cutaneous pleomorphic RMS is most common in adults. Immunoreactivity for cytokeratin was seen in 3 adult cases, a diagnostic pitfall in the differential diagnosis with sarcomatoid carcinoma. Recognition of rhabdomyoblastic cytologic features should prompt consideration of RMS. Based on limited follow-up, primary cutaneous RMS may still behave aggressively, especially in children.
Category: Dermatopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 86, Tuesday Morning


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