Myoepithelial cell-rich neoplasms: Cytologic features of benign and malignant lesions

Abstract

BACKGROUND Lesions that contain abundant myoepithelial cells may present as a diagnostic challenge in fine‐needle aspiration (FNA) specimens. Potential diagnostic problems may arise due to morphologic heterogeneity of myoepithelial cell‐rich lesions and difficulty in predicting malignancy in FNA specimens. An accurate diagnosis is important, because malignant myoepithelial cell‐rich lesions require a wider local excision and lymph node dissection. The authors characterized the cytologic features of myoepithelial cell‐rich lesions in an attempt to define the criteria that facilitate distinction between benign and malignant tumors. METHODS FNA biopsies of myoepithelial cell‐rich lesions with corresponding histologic specimens were selected. The cytology specimens were evaluated for the following criteria: cellularity, cell morphology, pleomorphism, chromatin pattern, presence of nucleoli, background material, necrotic debris, and presence of mitotic figures. A review of the histologic sections was performed for diagnostic confirmation. RESULTS Seventeen specimens from 17 different patients were selected. The histologic diagnoses were myoepithelial carcinoma (n = 6 patients), malignant mixed tumor with predominant myoepithelial carcinoma (n = 2 patients), epithelial‐myoepithelial carcinoma (n = 1 patient), and benign mixed tumor (n = 8 patients). The primary sites included the parotid gland (n = 10 patients), submandibular gland (n = 3 patients), minor salivary gland (n = 3 patients), and breast (n = 1 patient). Most specimens, whether they were benign or malignant, were very cellular. Pleomorphism, coarse chromatin, prominent nucleoli, mitotic figures, and necrosis were observed only in malignant specimens. Background material and ductal cells were seen in both benign and malignant specimens. CONCLUSIONS The presence of pleomorphism, coarse chromatin, prominent nucleoli, mitotic figures, and/or necrosis should raise the possibility of myoepithelial carcinoma in FNA specimens from myoepithelial cell‐rich lesions. Cancer (Cancer Cytopathol) 2004. © 2004 American Cancer Society.

Cytopathologic Analysis of Stroma-Poor Salivary Gland Epithelial/Myoepithelial Neoplasms on Fine Needle Aspiration

“…Most cytology studies have concentrated on either reviewing the general diagnostic pitfalls in a specific salivary gland epithelial/myoepithelial neoplasm or on case reports on various types of salivary gland epithelial/myoepithelial neoplasms [5,6,7,8,16,18,19,20]. When facing very difficult aspiration cytology cases, one of the most frequent causes of mistakes is that our differential diagnosis is too narrow.…”

“…The smears of the benign and malignant myoepithelial tumors are usually composed of various proportions of spindle, plasmacytoid, epithelioid and clear cells. The distinction between benign and malignant myoepithelial tumors is often made on histology based on infiltrative borders in the absence of overt malignant features [4,7]. Moreover, preoperative cytologic diagnoses of myoepithelial neoplasms have rarely been reported.…”

“…Although numerous reports have addressed the difficulties and differential diagnosis of a specific neoplasm, such as basal cell neoplasms, ADCC and EMC on FNA [5,6,7,8], studies focusing on general pattern recognition, such as aspirates of relatively bland-appearing epithelial/myoepithelial cells with no or rare stroma, are lacking. The main purpose of this study is to provide a detailed report of the cytomorphology of this group of FNAs with an emphasis on differential diagnosis and histologic follow-up.…”

Myoepithelial carcinoma of the parotid gland with bilateral thyroid involvement: A case report and review of the literature

“…The primary parotid MCA exhibits not only the lymph transfer predilection, which often transfers to cervical lymph nodes, but also distant metastasis, including the lungs, bones and liver (9). To the best of our knowledge, this case is the first to involve bilateral thyroids and cervical lymph nodes.…”

Myoepithelial carcinoma of the male breast: a rare case report

“…Metastases from myoepithelial carcinoma are described and usually they are hematogenous rather than lymphatic and they also appear to be restricted to cases of primary tumors with size greater than 2cm 5-9 . Cytologically, it shows hypercellularity and haphazard cellular arrangement with cell population mainly composed of spindle, epithelioid, plasmacytoid and clear cells 10 . The cellular morphology includes nuclear pleomorphism with mitotic figures.…”