Fine‐needle aspiration cytology of mammary adenomyoepithelioma: Report of a case with intranuclear cytoplasmic inclusions

Abstract

Adenomyoepithelioma of the breast is an uncommon lesion which may recur and rarely metastasizes. We report the fine-needle aspiration (FNA) findings in one case of mammary adenomyoepithelioma in which this tumor's unusual cytomorphology led to a cytologic diagnosis of malignancy, possible metastatic to the breast. Large, atypical, polygonal cells, some with intranuclear cytoplasmic inclusions, were most worrisome cytologically, but corresponded in the biopsied specimen to cells immunohistochemically documented to be of myoepithelial origin. Nests of epithelium and myoepithelial cells sometimes embedded in fibrous, stromal fragments were suggestive of an infiltrating pattern. Recognition of such unusual features in breast FNA is most important since definitive therapy may follow an FNA diagnosis of carcinoma in some clinical settings. In cases with unusual morphology, surgical biopsy should be recommended to clarify the nature of the lesion.

Adenomyoepithelioma of the Breast

“…Some authors have described the occasional presence of intranuclear cytoplasmic inclusions in the myoepithelial cells. 19,25 Scattered pleomorphic tumor cells were also found in two of the previously reported cases. 19,22 Sometimes there are tubular formations surrounded by an outer mantle of paler cells.…”

“…19,25 Scattered pleomorphic tumor cells were also found in two of the previously reported cases. 19,22 Sometimes there are tubular formations surrounded by an outer mantle of paler cells. 20 This resembles the cytologic appearance of epithelial-myoepithelial carcinoma of of salivary glands.…”

“…In general, there is an obvious biphasic tumor cell population. In addition to small clusters of blandlooking, mitotically inactive ductal cells and spindle myoepithelial cells, tumor cells with clear cytoplasm [18][19][20]24,25 or apocrine metaplasia 21,22,25 are commonly found. Apocrine cells, in fact, were conspicuous in the present cases.…”

Indeterminate and Erroneous Fine-Needle Aspirates of Breast with Focus on the ‘True Gray Zone': A Review

“…Smears are cellular with large clusters of epithelium and myoepithelium [55,56,57,58,59,60,61,62,63,64,65,66]. The ME cells can be difficult to recognize.…”

Melanoma Metastatic to the Breast

“…Although MMM cells often contain intranuclear cytoplasmic inclusions, they can be seen in benign breast tumors and breast carcinomas. 18,19 Although intracytoplasmic melanin pigment is most likely indicative of melanocytic differentiation, melanin pigment is present only in 40-70% of melanoma FNAs. 20 Since morphology alone may not provide sufficient information for the diagnosis of MMM, immunocytochemistry assumes an important role.…”