Low-grade epithelial-myoepithelial carcinoma of bartholin gland: report of 2 cases of a distinctive neoplasm arising in the vulvovaginal region.

We report 2 cases of a distinctive neoplasm arising from Bartholin gland and presenting as a vulval or vaginal mass. The tumors occurred in patients aged 44 and 51 years and were 2 and 3 cm in maximum dimension. In both cases, normal Bartholin gland tissue was identified adjacent to the lesion. The neoplasms were unencapsulated and largely well circumscribed but with a focally infiltrative edge. They were composed of tubular, trabecular, or insular arrangements with a double layer of inner cuboidal cells with round nuclei and outer cells with ovoid nuclei and clear cytoplasm, corresponding to epithelial and myoepithelial cells, respectively. Luminal eosinophilic colloid-like material was present. In both cases, a minor proportion of the neoplasm consisted of cribriform arrangements, creating an appearance reminiscent of adenoid cystic carcinoma, although the overall morphology was not typical of that lesion. Mitotic figures were identified in both cases, the mitotic count being 1 and 5/10 high-power fields. Immunohistochemically, the inner cells were positive with epithelial markers, including broad-spectrum cytokeratins and epithelial membrane antigen, and the outer cell layer was positive with myoepithelial markers p63, calponin, and alpha-smooth muscle actin. Both neoplasms exhibited diffuse strong immunoreactivity of the epithelial cells with c-kit. Activating mutations in KIT exons 9, 11, 13, and 17 and in platelet-derived growth factor receptor alpha exons 12, 14, and 18 were searched for by polymerase chain reaction and direct sequencing but were not identified. We believe this represents a low-grade carcinoma arising from Bartholin gland composed of a dual population of epithelial and myoepithelial cells and closely resembling the salivary gland neoplasm termed epithelial-myoepithelial carcinoma. We propose the term low-grade epithelial-myoepithelial carcinoma of Bartholin gland.