Intramuscular cysticercosis of the forearm mimicking a soft tissue tumour

Abstract

A man in his 20s presented with a painless, slow-growing firm swelling in the anterolateral aspect of his left forearm. The swelling had been present for 1 year and measured 10×12 cm. Clinically, a differential diagnosis of soft tissue sarcoma, lipoma, neurofibroma, dermoid cyst and hydatid cyst of the extremity was considered. MRI suggested a primary intramuscular hydatid cyst. However, fine-needle aspiration was inconclusive, and ELISA for immunoglobulin G antibodies to echinococcal antigen in serum was negative. A wide-local complete surgical excision of the lesion was planned. Intraoperatively, a well-defined, tense cystic swelling with surrounding dense adhesions was found within the intramuscular plane. Histopathological examination of the cyst wall revealed cysticercosis. The patient recovered uneventfully. This case highlights that solitary intramuscular cysticercosis, although rare, should be included in the differential diagnosis of an isolated soft tissue mass, particularly in endemic areas.