Breast Apocrine Adenoma
An apocrine adenoma of the breast is a rare kind of adenosis tumor. Multiple layers of accompanying apocrine cells characterize this type of tumor. An adenoma is a disorganized pseudo-mass which features varying amounts of fibrous, fat, and glandular tissues. Depending upon the most prominent features of the lesion, the specific name will change accordingly.
Other adenomas get their name according to familiar cell formations, or due to the presence of other hyperplasic cells accompanying the lesion. Apocrine adenoma is one of the latter.
This page is getting a little bit out-of-date, but still pretty useful. However, I have a newer version with more up-to-date information on Benign breast conditions, including apocrine adenoma.
Apocrine cells are ‘secretion’ cells, common in various glands of the body and especially in the skin, but there are a small number of apocrine cells in the breast. While apocrine metaplasia is a very common and benign neoplasm that affects most women at some point in their lives, a breast apocrine adenoma is very rare.
Histological features typically show several layers of apocrine cells
In terms of its histological appearance, apocrine adenoma is typically a well-circumscribed tumor with varying amounts of:-
cell formations, and several layers of apocrine cells.
Component cells of breast apocrine adenomas also tend to be quite densely packed, but they might also be slightly cystic in nature (i.e. full of fluid)
The cytoplasm of individual cells tends to be eosinophilic (readily stained by protein dyes) and granular. Nuclei tend to be of normal size and shape, but there may be some evidence of cell mitosis (division).
In terms of mammography, apocrine adenomas do not have a distinctive appearance, and so a biopsy is almost always necessary.
Is apocrine adenoma in the breast of concern for breast cancer?
Breast apocrine adenoma is considered benign. The term ‘apocrine adenoma‘ is sometimes informally used to indicate a widespread growth of apocrine metaplasia, or sometimes for sclerosing adenosis with extensive apocrine metaplasia. Occasionally, the finding of unusual cytologic features (cytologic atypia) might mimic the appearance of invasive apocrine breast carcinoma, so a thorough evaluation is advised.
There is no evidence for progression from apocrine adenoma to breast cancer
In addition to the breast, apocrine adenomas have been known to occur in the perianal region, the eyelid, and the axilla. There are suggestions that apocrine adenomas occuring in other parts of the body, such as the axilla, might be a ‘middle‘ step in a succession from apocrine hyperplasia to apocrine carcinoma, but there is no evidence of this for apocrine breast adenomas.
Whenever a curious neoplasm such as an apocrine adenoma is discovered during breast cancer screening or following a clinical exam, prudent follow-up measures common to all such neoplasms will likely be undertaken. These would include detailed imaging studies, biopsies, and follow-up checks at a reasonable interval.
For further reading, I suggest you visit this page on breast apocrine metaplasia, this page too which has some information on apocrine breast cancer, go to this page for breast adenocarcinoma with spindle cell metaplasia, as well as this page about sclerosing adenosis.
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