SOLID ALVEOLAR RHABDOMYOSARCOMA OF THE HAND IN ADOLESCENCE - A CLINICAL, HISTOLOGIC, IMMUNOLOGICAL, AND ULTRASTRUCTURAL-STUDY

Rhabdomyosarcoma (RMS), a high-grade, malignant, skeletal muscle tumor , represents approximately 5% of neoplasms in children. The poorly dif ferentiated forms of RMS are often not easily diagnosed and classified , Among the four histologic variants, alveolar RMS is the least freque ntly reported subtype. A poorly differentiated solid variant of alveol ar RMS occurred on the right hand of a 16-year-old girl. Because of th e tumor size, local invasiveness, and occurence of cutaneous and breas t metastases at presentation, the clinical staging was group IV (T2/N0 /M1). Surgical excisions of the primary and metastatic locations were performed and chemotherapy with vincristine, dactinomycin, cyclophosph amide, and doxorubicin was administered. Light and electron microscopy studies revealed a solid proliferation with a focal alveolar pattern of monomorphous, small, round neoplastic cells without easily detectab le muscular morphologic features. The skeletal muscle origin was revea led by the positive immunostaining for desmin, alpha-sarcomeric actin, muscle-specific actins, and enolase, and confirmed by immunoblotting for desmin. Despite the age of our patient, which is considered by som e authors an independent predictor of outcome, all prognostic variable s were unfavorable. However, a disease-free interval during three year s of follow-up underlines the importance of multidisciplinary regimens for the treatment of this rare solid tumor of childhood and adolescen ce.