Acinic Cell Carcinoma of the Breast Arising in Microglandular Adenosis

Abstract

Acinic cell carcinoma is a rare breast tumour belonging to salivary gland-like tumours of the breast. They are “triple-negative” breast cancers even if their biological behaviour seems to be more favourable. Herein we present an acinic cell carcinoma arising on a background of typical and atypical microglandular adenosis in a 58-year-old woman, along with a review of the literature.

Acinic cell carcinoma of breast: morphologic and immunohistochemical review of a rare breast cancer subtype

“…Most reported cases of breast AcCC describe variation in the tumor architecture, with solid and nested components admixed with areas of tubular and microglandular morphology. The phenomenon of tubules with central luminal extracellular “colloid-like” material was described as “MGA-like” in several articles [4,7,13], whereas other articles interpreted the appearance as suggestive of true MGA [22]. Interestingly, in 11 cases where collagen IV and laminin immunohistochemistry was performed, these MGA or MGA-like areas were entirely negative for these basement membrane markers in 8 cases [7,13,19,24].…”

“…In the remaining 3 cases [12] (including the 2 cases reported in this article), very focal positivity was noted. The cytologic appearance of tumor cells, with coarse eosinophilic granules and globules, was labeled “Paneth cell like” in 11 cases [4,7,16,19,22,24]. Seven cases also reported a population of cells with basophilic cytoplasm [4,11,19]; in 4 of these cases [4] (including case 2 from this article), cells with basophilic and eosinophilic cytoplasmic granules were located together within the same tubular structure, giving a variegated appearance (Fig.…”

“…Seven cases of breast AcCC have had ultrastructural analysis [1,7–10,22]. In all 7 cases, the dominant feature was the presence of multiple, variably sized cytoplasmic granules, whereas ribosomal endoplasmic reticulum was prominent in 5 cases, and abundant mitochondria were noted in 3 cases.…”

Are acinic cell carcinomas of the breast and salivary glands distinct diseases?

“…AcCCs of the breast are extremely rare. Only 39 cases have been described in the English literature to date, usually as case reports or small case series . In addition to immunoreactivity for serous differentiation markers, AcCCs of the breast have been reported to display a triple‐negative phenotype; interestingly, however, at variance with the common forms of triple‐negative breast cancer (TNBC), breast AcCCs are reported to have indolent clinical behaviour …”

Carcinoma arising in microglandular adenosis of the breast: triple negative phenotype with variable morphology

“…Acinic cell carcinoma of the breast carcinoma is a rare tumor similar to the acinic cell carcinoma of the parotid gland [20]. Two studies [21,22] reported 2 case of acinic cell carcinoma arising in MGA, and suggested a close relationship between the two lesions. Nevertheless, some of the morphological, immunohistochemical and ultrastructural features of these lesions are different, so a histogenetic link remains to be proven.…”