Mucoepidermoid carcinoma of the salivary glands

correlation between histomorphological architectures and imprint cytology

Abstract

Objective: Mucoepidermoid carcinoma is a tumor composed of variable proportions of mucus-producing, intermediate, squamous, and clear cells and represents a wide spectrum of malignant potential. A grading system that subtypes this tumor into low, intermediate, and high-grades according to cellular atypia and histological architecture has been generally accepted. We evaluted cytological appearance corresponding to these 3 grades.
Method: Cases capable of sufficient study, which arose in the parotid and intraoral minor salivary glands, were collected from the registry file of the Department of Pathology, Kurume University School of Medicine. All imprinted cytologic smears obtained in intraoperative rapid diagnosis procedure were stained with Papanicolaou, Giemsa, Peroidic acid Schiff, and Alcian blue stains.
Results: Neoplastic cells appeared forming loose, small clusters or isolated in the background between clusters. Squamous cells appeared more predominantly in high-grade cases, while mucus-producing and intermediate cells were valid in low-grade cases. Cytological atypia was remarkable in high-grade cases, which included pleomorphic undifferentiated cells and commonly lacked definable mucusproducing cells. No characteristic arrangement and little further difference between the 3 grades were recognized except in cell proportion, cytological, atypia and pleomorphism.
Comments: Important diagnostic problem lies in highgrade cases, in which occasionally mucin-production is hardly evident. Intermediated-or high-grade mucoepidermoid carcinoma should be considered when tumors predominantly consist of squamous cells, especially in major salivary glands, except with evident preexisting pleomorphic adenoma. In such an instance, In-2 type cells described by Kawahara et al.(1999) may be helpful for accurate diagnosis.