A Rare Presentation of Schwannoma as a Purely-Cystic Superficial-Intermuscular Extra-Spinal Swelling over Upper Back.

Abstract

Schwannomas are rare tumours arising from peripheral nerve sheath. Here, a 44-year-old lady came to our clinic with an asymptomatic progressively-enlarging swelling over her upper back. It was fluctuant, with an absence of pain and tenderness. MRI showed a benign, purely-cystic, superficial-intermuscular, extra-spinal swelling nearby upper thoracic vertebrae. Complete surgical excision proceeded smoothly through a well-defined plane between the swelling and the muscles. It was not attached to any identifiable nerve. A 6.5x5.0x2.5 cm ovoid lesion with a glistening whitish-grey capsule was excised and wound reconstructed in layers. Histopathology showed hypercellular areas with nuclear palisading or oval-shaped Verocay bodies. Only S-100 tested positive amongst the five-antigen immunohistochemistry, thus establishing the diagnosis of a schwannoma. Postoperatively, a one-year follow-up period was uneventful. Schwannomas can surprise clinicians by arising anywhere and with atypical presentations. It needs to be in the differential diagnoses of any asymptomatic slowly-growing lesion.