Alveolar rhabdomyosarcoma in the skin of the abdominal wall in an elderly patient: A case report

Alveolar rhabdomyosarcoma (ARMS) is a type of primitive round cell tumor that mainly develops in adolescents and young adults. Immunohistochemically, the expression of myogenic markers is a key clue for pathological diagnosis, and an aberrant expression of neuroendocrine markers and/or cytokeratin has also been reported. Therefore, an unusual clinical course complicated with aberrant neuroendocrine expression may make the diagnosis of ARMS difficult. In this report, we present a case of ARMS that developed in the skin of the abdominal wall in an elderly patient; the tumor cells expressed neuroendocrine markers. ARMS should be considered as a differential diagnosis of primitive round cell tumors in elderly patients and it is essential to confirm concurrent myogenic differentiation and PAX3/PAX7–FOXO1 fusion gene expression to make a pathological diagnosis. Keywords: Alveolar rhabdomyosarcoma, Primitive round cell tumor, Neuroendocrine marker, PAX3/PAX7–FOXO1 fusion gene, High-sensitivity RT-PCR