A rare presentation of an abductor hallucis soft tissue mass: A case report

Schwannomas can present as soft tissue masses in the foot and ankle that mimic other conditions. This report presents a rare case of schwannoma arising within the abductor hallucis muscle belly in a 53-year-old female with past medical history of rheumatoid arthritis. The patient presented with a year-long history of left foot pain and a slowly enlarging, palpable mass on the plantar medial aspect of the foot. Initial evaluation and imaging revealed a well-circumscribed soft tissue mass with internal vascularity. However, due to medical history and overlapping clinical and imaging features, the differential diagnosis, among others, included rheumatoid nodules. Surgical excision of the mass was performed, and histopathology confirmed the diagnosis of traditional schwannoma. This report underlines the diagnostic challenge of distinguishing schwannomas from rheumatoid nodules and other types of soft tissue masses, specifically in patients with autoimmune disease. We discuss the clinical, radiological, and pathological aspects of this rare tumor. Definitive diagnosis requires histological analysis, as imaging alone may be inconclusive.