Cytology of melanotic schwannoma in a fine needle aspirate and pleural fluid - A case report

BACKGROUND: Melanotic schwannoma (MS) is a rare pigmented neural tumor most commonly occurring in the paraspinal region and involving spinal nerve roo ts and sympathetic ganglia. Few case reports describe the fine needle aspir ation (FNA) cytology of MS. We report an additional case and for the first time describe the cytologic findings of MS in pleural fluid. CASE: A 44-year-old man presented with a 9.0-cm paraspinal mass associated with multiple lung nodules. FNA cytology of the paraspinal mass showed soli tary and syncytially arranged spindled cells, with prominent nucleoli and v ariable amounts of cytoplasmic brown pigment. In pleural fluid, prominent i solated single cells were rounded and had a signet ring cell morphology. Tu mor cells in both the aspirate and pleural fluid expressed S-100 protein an d HMB-45. CONCLUSION: The FNA cytology findings of MS correlate well with the histolo gic findings. In pleural fluid, however, the cells are epithelioid, and som e have a signet ring morphology, mimicking adenocarcinoma.