Perianal and Perineal Spindle Cell Variant of Embryonal Rhabdomyosarcoma in an Infant.

We present a case of a perianal and perianal spindle cell variant of embryonal rhabdomyosarcoma (RMS). A 3-month-old male child presented with a firm mass in the perianal region. The mass measured 5 cm × 3 cm × 2 cm was surgically removed. Biopsy was performed; it showed embryonal RMS. Immunohistochemical (IHC) stains were performed using vimentin, myogenin, spinal muscular atrophy, and muscle-specific actin, which all showed positive results. The histological examination and IHC stains were consistent with a spindle cell variant of embryonal RMS.