OBJECTIVETo study the pathological characteristics of salivary malignant myoepithelioma with characteristic multinodular architecture.

METHODSTo observe the histologic and cytologic characteristics of 19 cases of de novo salivary malignant myoepithelioma with multinodular growth pattern. Immunohistochemistry of calponin, SMA, S-100, GFAP, cytokeratin, PCNA was done on 11 cases and ultrastructure was observed on 3 cases.

RESULTS19 tumors presented characteristic multinodular growth pattern, mostly accompanied by central necrosis. Neoplastic nests invaded the surrounding normal tissue and tumor cells displayed a variety of pleomorphism. Epitheliod cell was the most predominant cell type. Tumor-related extracellular matrix formation was revealed among tumor cells. Immunohistochemical staining demonstrated that the tumor cells were positive for calponin, SMA, S-100, GFAP, AE1/AE3, CKH and PCNA. Myofilaments were found in neoplastic cell cytoplasm under the electron microscope.

CONCLUSIONHistologic and cytologic observation, immunostaining and ultrastructural study all supported the myoepithelial and malignant nature of the tumor.

Diagnosis, Differential ; Humans ; Myoepithelioma ; diagnosis ; pathology ; Parotid Neoplasms ; diagnosis ; pathology ; Salivary Gland Neoplasms ; diagnosis ; pathology