Although the histopathologic features of
malignant peripheral nerve sheath tumors (
MPNST) have been well-described, the cytologic features are less well-characterized. We retrospectively reviewed 4 aspiration specimens from 3 patients with histologically-proven
MPNST. The biopsy specimens were obtained from the primary
tumor (1 case), a local recurrence (2 cases), and a pulmonary
metastasis (1 case). The patients were women, aged 42, 61, and 70 yr. The primary
tumors arose from the left neck and elbow, and from a
neurofibroma in the right medial thigh. The latter patient had
von Recklinghausen's disease. Cardinal cytomorphologic features included aggregates and single cells with ovoid to elongated, and comma to
serpentine shapes, as well as hyperchromatic nuclei surrounded by delicate, tapering cytoplasm. Nuclear pleomorphism ranged from slight to marked. Multinucleated giant cells were seen in 2 cases. In general, the degree of nuclear variability within each individual case exceeded that typically observed with
synovial sarcoma or
fibrosarcoma. Although the cytomorphologic features may strongly suggest
MPNST, clinical correlation is necessary and immunocytochemistry (i.e.,
S-100 protein) may help to distinguish
MPNST from other
spindle-cell sarcomas. Origin from a nerve trunk or preexisting
neurofibroma, or occurrence in a patient with
von Recklinghausen's disease, confirms the diagnosis of
MPNST.