[472] Mucoepidermoid Carcinoma: A Cyto-Histologic Correlation with Special Emphasis on Diagnostic Cytologic Features

TV Wade, VA LiVolsi, KT Montone, MD Feldman, ZW Baloch. Hospital of the University of Pennsylvania, Philadelphia, PA

Background: Mucoepidermoid carcinoma (MEC) is the most common malignant tumor of the salivary glands; the majority of MEC occur in the parotid resulting in accessibility to biopsy by fine needle aspiration (FNA). However, the histologic complexity and morphological variability of this tumor may lead to interpretative difficulties on cytologic examination. In this study we attempt to identify morphologic features that may be useful in the FNA diagnosis of MEC.
Design: The cohort included 22 cases of MEC with preoperative FNA. Cytology and histology slides and clinicopathologic features were reviewed; cases were assessed for the following: % cystic component, nuclear atypia, necrosis, extracellular mucin, mucus cells, intermediate cells, oncocytes, cells with foamy/clear cytoplasm, keratinized cells and lymphocytes.
Results: 21/22 (95%) of MECs arose in the parotid gland (average size 1.9 cm). On FNA 7/22 (32%) cases were diagnosed as consistent with and 5/22 (23%) as suggestive of MEC; 6/22 (27%) as salivary gland neoplasm and 4/22 (18%) no tumor seen. The histologic grade was low in 12/22 (55%), intermediate 9/22 (45%) and high in 1/22 (4%) cases; neural invasion in 4/22 (18%) and lymph node metastasis in 1/22 (4%) cases. The cystic component was ≥50% in 17/22 (77%) cases. The morphologic features prevalent in both histology and FNA specimens were: mucus cells (95%), cells with foamy/clear cytoplasm (73%), intermediate cells (86%), presence of extracellular mucin (91%) and lymphocytes (86%). Oncocytic cells were seen in 23% and keratinized cells in 14% cases. Interestingly, cases with oncocytic cells and lymphocytes were interpreted as favor Warthin's tumor on FNA.
Conclusions: Presence of mucus cells, histiocytic type cells with foamy/clear cytoplasm, intermediate cells and lymphocytes in a mucinous background are strong diagnostic indicators of MEC; the presence of oncocytic cells along with the above-mentioned features should not refrain from diagnosing MEC in FNA specimens.
Category: Cytopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 56, Wednesday Afternoon


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