ABSTRACT
Alveolar rhabdomyosarcoma (RMS) is an aggressive soft tissue mass demonstrating rapid growth, dissemination, and leptomeningeal spread. Primary diagnosis is usually established by core biopsy. In rare cases, cytopathologic evaluation is indicated to identify recurrent or metastatic disease. We present a case of a 24-year-old man with a previously diagnosed alveolar RMS of the foot who presented to our institution with back pain. A lumbar puncture was performed and the cerebrospinal fluid (CSF) showed atypical cells demonstrating nuclear enlargement, eccentricity, binucleation, and frequent karyorrhexis. Laminectomy and cytogenetic studies were subsequently performed, confirming metastatic disease. There are few published reports on the CSF appearance of RMS. However, because leptomeningeal involvement by RMS is primarily evaluated by lumbar puncture, awareness of the cytologic features is important for patient management.