[1297] Mucinous Myoepithelioma, a Previously Unrecognized Variant

Carlos J Esteva, Lee J Slater, Douglas R Gnepp. Warren Albert Medical School of Brown University, Rhode Island Hospital, Providence, RI; Scripps Oral Pathology Service, San Diego, CA

Background: Myoepithelial neoplasms are salivary gland tumors composed almost exclusively of cells with myoepithelial differentiation that may exhibit spindle, plasmacytoid, epithelioid or clear cytoplasmic features. They are uncommon accounting for 1.5% of benign & <2% of malignant salivary gland tumors. We have encountered a subset of confirmed benign & malignant myoepithelial tumors containing intracellular mucin. This represents a unique, previously undescribed subtype that does not fit in the current classification system. This paper presents 2 unique myoepitheliomas with prominent intracellular mucin.
Design: 29 myoepithelial neoplasms from our surgical pathology, teaching & consult archives from 1997-2011 were reviewed for the presence of intracellular mucin.
Results: 18 adenomas & 11 carcinomas were reviewed from patients 28-87 years old; 17 women & 12 men. All myoepithelial tumor cell types & growth patterns were included. Cases were reviewed by 2 authors for the presence of intracellular mucin; first by H&E, then by Mucicarmine (26 cases) and Periodic Acid Schiff (PAS) with & without diastase (19 cases). Most cases examined showed mild to prominent extracellular/stromal mucin, without evidence of intracellular mucin. Two tumors had abundant intracellular mucin with H&E staining, confirmed by mucicarmine & PAS diastase staining in 1 case and by PAS diastase only in the other. The benign case arose in the parotid gland of a 69yo male. It was encapsulated, composed of sheets of closely packed nests & trabeculae of plasmacytoid to polygonal cells compartmentalized by slender fibrovascular septa. Tumor cells had abundant eosinophilic to foamy grayish-blue cytoplasm, frequently containing intracellular mucin, mild nuclear pleomorphism & fine peppery chromatin with inconspicuous nucleoli. It was positive for cytokeratin, SMA, S100 & GFAP. The 2nd tumor arose in the hard palate of a 75yo female. It was multinodular, well-circumscribed, focally invasive & was composed of nests & sheets of cells with moderate nuclear pleomorphism, prominent nucleoli & abundant lightly eosinophilic cytoplasm with a focally prominent plasmacytoid-type configuration. Throughout much of the tumor were areas with prominent intra-cytoplasmic mucinous-type secretions & focal areas with extracellular mucin material. It was positive for Calponin, Cytokeratin, S100, CK7, CEA & GFAP.
Conclusions: We propose a new variant of myoepithelioma, mucinous type, in which there is focal or abundant gray to bluish intracellular mucin.
Category: Head & Neck

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 166, Tuesday Afternoon


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