Cutaneous metastasis of alveolar rhabdomyosarcoma in a young adult: A rare presentation and diagnostic challenges

Summary: Abstract Body: We present a 22-year-old woman with a history of metastatic alveolar rhabdomyosarcoma (ARMS) of the left foot who developed progressive skin lesions on the left thigh and back. ARMS is an aggressive subtype of rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children. Notably, ARMS has a 5-year survival rate of 50-70% for localized cases and 20-30% for metastatic cases. When metastasis occurs, cutaneous sites are exceedingly rare, with only 14 reported cases in the literature to date. However, it is important to recognize these cutaneous findings given that metastasis to the skin indicates advanced disease with a poor prognosis. Despite amputation of her left foot (the primary site of her ARMS) and treatment with multiple chemotherapy regimens, this patient experienced recurrent pulmonary and hepatic metastases. She was admitted for worsening shortness of breath and at that time, our inpatient dermatology team was consulted for evaluation of skin lesions on the left thigh which were worsening over the course of one month. On physical examination, multiple tender, erythematous to pink nodules with red-yellow exudate and central necrotic crust were observed. A punch biopsy confirmed the lesions as metastatic cutaneous ARMS. This case underscores the rarity of cutaneous ARMS and the scarcity of documented physical exam findings in the literature. Cutaneous ARMS metastasis can be an early visible sign of systemic disease and often signifies an advanced disease state, making early recognition crucial for timely intervention and improved patient outcomes, thus highlighting the need for heightened awareness among dermatologists. Matthew Yan¹, Shannon Wongvibulsin¹, Michael Nguyen¹ 1. Dermatology, University of California Los Angeles David Geffen School of Medicine, Los Angeles, CA, United States. UV Biology/Injury and Non-melanoma Cancers