Primary Pleural Schwannoma Mimicking a Pleural Neoplasm: A Case Report

Background: Primary pleural schwannoma is an uncommon peripheral nerve sheath tumour and may mimic a primary or metastatic pleural neoplasm on imaging. We report a 55-year-old woman with a four-year history of left-hand tingling followed by persistent dull aching left-sided chest pain, without respiratory or constitutional symptoms. Contrast-enhanced computed tomography demonstrated a well-defined pleural-based heterogeneous enhancing mass adjacent to the apicoposterior segment of the left upper lobe, with central necrosis and internal calcification, involvement of the extrapleural fat plane, but no rib erosion or extrathoracic extension. Magnetic resonance imaging showed a well-marginated lesion measuring approximately 3.8 × 5.3 × 4.0 cm. Core biopsy revealed a spindle-cell tumour without mitotic activity. Immunohistochemistry showed SOX10 positivity, diffuse strong S100 positivity and calretinin positivity, with negative CD34, CD56, desmin, ALK-1 and TTF-1; Ki-67 was <1%, supporting schwannoma. This case highlights the value of integrating imaging, histopathology and immunohistochemistry when evaluating an unusual pleural-based mass.

Keywords: Pleural schwannoma; peripheral nerve sheath tumour; pleural mass; SOX10; S100; chest pain.