Subperiosteal Schwannoma of Pelvis- A Rare Case and Review of Literature.

Schwannoma are benign tumours of the nerve sheath. They are commonly found in the soft tissue, but its presence in the bone is extremely rare. We herein present a case of 34-year-old man with two adjacent pelvic subperiosteal schwannomas. Computed Tomography (CT) scan showed osseous pressure erosion and Magnetic Resonance Imaging (MRI) showed two cystic signal intensity lesions, one near superior aspect of right posterior iliac wing and another inferior to it with adjacent cortical pressure erosion. The tumour was excised en bloc and on histopathological examination, the diagnosis was confirmed as subperiosteal schwannoma. To our knowledge, this is the first case report of subperiosteal schwannoma involving the pelvis. When a surface cystic lesion is encountered, subperiosteal schwannoma should be considered as a possible differential diagnosis.