TEACHING CASESolid variant of mammary “adenoid cystic carcinoma with basaloid features” merging with “small cell carcinoma”
Introduction
Adenoid cystic carcinoma (ACC) of the breast is a rare neoplasm (<1% of breast carcinomas) with an excellent prognosis. As in salivary glands, a variety of microscopic growth patterns (cribriform, glandular, trabecular, solid, and basaloid) have been described in the breast. It has been reported that solid and basaloid variants are associated with a more aggressive clinical course [2], [8], [9] and have been considered as” high grade” tumors. Recently, Shin and Rosen [11] have described a series of nine cases of a rare subtype of “solid adenoid cystic carcinoma with basaloid features”(sbACC) in the breast, reporting on a differential diagnosis from other neoplasias, including primary small cell carcinoma (SCC) of the breast. This study describes a very rare case of mammary neoplasia in which solid, basaloid adenoid cystic areas (sbACC) merge with more extensive areas of primary “SCC”.
Since these two neoplastic histotypes are very rare in the breast, their histological and immunohistochemical features have been studied to provide a pathogenetic explanation for their coexistence in the same neoplasia.
Section snippets
Case report
A 40-year-old woman, with type I diabetes mellitus, no risk factors for oncological disease, presented a nodule (about 2 cm) discovered in the central quadrant in the retro-areolar zone of the left breast 4 months previously.
Clinical examination showed that the nodule was circular, with indistinct limits, subcutaneously mobile, but partly attached to the underlying glandular layer. No alterations of the areola or nipple were observed. Palpation of the left armpit identified a mobile, non-painful
Discussion
Mammary ACC is a tumor with a good prognosis and is histologically indistinguishable from ACC arising from other sites. As in the salivary glands, a variety of microscopic growth patterns (cribriform, glandular, trabecular, solid, and basaloid) have been described in the breast.
The solid and basaloid variants have been reported to be associated with a more aggressive clinical course [2], [8], [9] and have been considered “high grade” tumors.
The “sbACC” is a rare subtype of ACC, described by
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