Differential diagnosis of the pleomorphic aspiration biopsy sample of nonepithelial lesions.

The major problem confronting the cytopathologist in interpretation of the pleomorphic aspiration biopsy sample (ABS) of nonepithelial lesions is to provide a reasonable differential diagnosis, since the presence of cellular pleomorphism alone does not always denote malignancy. One must be fully cognizant of a vast number of pathologic processes to make a correct interpretation. Some indication of the extent of the problem and the potential diagnostic pitfalls are outlined in selection of nonneoplastic processes and benign and malignant tumors of mesenchymal origin presenting as pleomorphic ABSs.