OBJECTIVE: To analyze the importance of unique cytoarchitectural patterns and the immunohistochemical profile in the diagnosis of myoepithelial carcinomas.

DESIGN: Retrospective case analysis.SETTING: Tertiary cancer center.

PATIENTS:

A total of 51 patients with myoepithelial-rich carcinomas diagnosed over a 14-year period were studied for demographic data and tumor histologic characteristics and biologic behavior.

MAIN OUTCOME MEASURES:

We analyzed various histopathologic parameters and an immunohistochemical profile consisting of pan-cytokeratin (Pan-CK), epithelial membrane antigen (EMA), CD10, smooth-muscle actin (SMA), S-100 protein, p63, calponin, and carcinoembryonic antigen (CEA).

RESULTS:

The parotid gland (n = 15) and the palate (n = 15) were common sites involved. The cell types encountered were epithelioid, stellate, plasmacytoid, spindle, clear, and mixed with myxoid, hyaline, or myxohyaline stroma. Immunohistochemical analysis revealed vimentin (100%), CK (74%), EMA (27%), CD10 (62%), SMA (35%), S-100 protein (82%), p63 (28%), and calponin (98%) positivity and CEA (100%) negativity. Cervical node dissection was performed in 17 cases: 7 showed nodal metastasis, 2 with pure spindle-cell morphologic characteristics and 3 with spindle cells mixed with other cells. Distant metastasis was noted in 3 of these 7 cases: 2 of these 3 cases showed spindle-cell morphologic characteristics.

CONCLUSIONS:

Myoepithelial carcinomas showed varied cell types and patterns leading to a wide range of differential diagnoses. Immunohistochemical analysis helped determine the diagnosis. Spindle morphologic characteristics were observed with nodal and distant metastasis.