Cytologic characteristics of peripheral neuroectodermal tumors in fine-needle aspiration smears: a retrospective study of three pediatric cases.

Cytologic diagnosis of peripheral neuroectodermal tumors (PNT) on fine-needle aspiration (FNA) smears represents a challenge to the cytopathologist. Usually ancillary studies are used to achieve definitive diagnosis. We retrospectively examined FNA material from three cases of PNT with the aim of identifying their features. Positive and negative cytologic findings were recognized. Positive features for PNT included the presence of: rather uniform appearance of the cells, which display scant but almost always-present perinuclear clear cytoplasm (suggesting a bland epithelial tumor); nuclei with distinctively smooth nuclear membrane contour, finely granular chromatin, and one or two small nucleoli (suggesting neuroendocrine anlage); and organization of the cells singly or in cohesive clusters. Negative findings included the absence of: frequent mitotic figures, large nucleoli, nuclear pleomorphism, cellular debris, histiocytes, and polymorphonuclear leucocytes. The smears appeared clean, with small, uniform cells having features suggesting a neuroendocrine epithelial tumor. These findings may prove useful for accurate cytologic diagnosis and differentiation of PNT from other small blue round cell tumours (SBRCT) of soft tissues without the use of ancillary studies since, when properly evaluated, cytomorphology of the latter group of tumors is more heterogeneous than generally believed.