Malignant melanotic schwannoma fine-needle aspiration biopsy findings.

We describe the cytologic, histologic, and clinical features of two cases of melanotic schwannoma, arising in the neck and superior mediastinum, respectively. Cytologic findings in both cases included the presence of cells with heavily pigmented cytoplasm, showing long branching projections. The cells were arranged in clusters, with ill-defined boundaries. Histologic findings included interlacing fascicles of cells, with abundant melanin pigment, calcification, and necrosis. Immunohistochemical stains were positive for S. 100 protein and anti-human melanoma (HMB45). Both patients died with metastases.