Ancient schwannoma of the gluteal region: a case report.

Schwannomas are benign peripheral nerve sheath tumors that rarely develop in the gluteal region. We describe a 35-year-old man with a 5-year history of a slowly enlarging left gluteal mass, which became painful after superficial ulceration developed. Ultrasonography and magnetic resonance imaging demonstrated a well-circumscribed, heterogeneously enhancing solid lesion without evidence of invasion. Because malignancy could not be excluded on imaging, the mass was excised en bloc with clean margins without prior biopsy. Histopathology revealed encapsulated spindle cells arranged in a palisading pattern, with cystic degeneration and hemorrhage; immunohistochemistry was positive for S100, vimentin and calponin, confirming the diagnosis of ancient schwannoma. No recurrence occurred during 3 years of follow-up. Schwannoma should be considered in the differential diagnosis of gluteal mass, even in the absence of a positive Tinel sign.