An occult primary malignant melanoma in a black. Initial diagnosis by aspiration biopsy cytology of a metastasis.

Aspiration of tissue through a fine needle is a feasible way of obtaining material for diagnosis. The value, readability, and specificity of aspiration biopsy cytology is illustrated by a case in which nonpigmented neoplastic cells from an axillary mass were interpretable as metastatic malignant melanoma. That interpretation was later confirmed by conventional and electron microscopy of tissue. A search for the primary lesion led to recognition and excision of a malignant neoplasm with Schwannian features that probably arose in a congenital nevus.