Fine needle aspiration cytology of metastatic malignant schwannoma. A case report.

A metastatic malignant schwannoma diagnosed by fine needle aspiration (FNA) biopsy in a 56-year-old man is reported. Cytologic examination of smears and cell blocks prepared from aspirates of a vertebral mass suggested the presence of metastases from a previously excised malignant schwannoma on the right leg. Electron microscopic and immunocytochemical studies on the aspirate supported the diagnosis, as did the patient's clinical history and previous pathology and the radiographic demonstration of metastatic lesions in the lung. The cytologic findings (cells with oval-to-spindled nuclei and ill-defined cellular borders suspended within a delicately fibrillar eosinophilic matrix) are discussed in light of the histologic diversity of this lesion and the problems of distinguishing it from other sarcomas. The ability to diagnose metastatic malignant schwannoma by FNA emphasizes the value of this technique.