Atypical plasmacytoid monomorphic adenoma of salivary glands of the tongue: Cytologic,histologic, immunohistochemical,and ultrastructural findings

We describe the case of an 11‐yr‐old boy with a 2.5‐cm‐diameter soft tumor superficially located at the dorsal aspect of the tongue. Fine‐needle aspiration cytology smears showed plump epithelioid cells with round to mildly oval nuclei and open chromatin. One or two nucleoli of intermediate size were noticed in each nucleus. These cells appeared singly or in small groups. The findings were interpreted as containing plasmacytoid cells coming from an adenoma of salivary gland origin. The histologic examination of the surgical specimen revealed noncohesive, pleomorphic polygonal cells combining plasmacytoid/rhabdoid cytoplasmic features, with mild to moderate nuclear pleomorphism. One mitotic figure was observed per 10 high‐power fields. Immunoreactivity was strongly positive for vimentin and S‐100 protein, less intense for the cytokeratins, and negative for smooth muscle actin, muscle‐specific actin, myoglobin, and GFAP. No ultrastructural evidences of myogenous differentiation were found. We propose that this case represents an unusual atypical variant of plasmacytoid monomorphic adenoma. Diagn. Cytopathol. 1999;20:29–33. © 1999 Wiley‐Liss, Inc.