mammary apocrine carcinoma

Apocrine carcinomas comprise ∼1% of all breast cancers and are characterized by large cells bearing abundant eosinophilic granular cytoplasm, round nuclei, and prominent nucleoli.

They are typically estrogen receptor/progesterone receptor/HER2 negative, making them unresponsive to typical hormonal or HER2-based chemotherapy.

Synopsis

  1% of all breast cancers
 androgen receptor +

Microscopy

By gross appearance apocrine breast tumors are generally indistinguishable from other invasive breast carcinomas.

Macroscopy

When examined by a microscope apocrine breast tumors usually appear as sheets, cords, and sometimes tubules of neoplastic cells. The most obvious cytological features of apocrine carcinoma are large amounts of eosinophilic, granular cytoplasm ( containing particles or grains, which stain more easily), tumor cells with well-defined margins, and large vesicular nuclei which are often round or oval. The nucleus to cytoplasm ratio is about 1:2. Apocrine carcinoma cells frequently reveal ‘apocrine snouts’. These ‘snouts’ are actually accumulations of secreted granules in the apical cytoplasm ( the cytoplasm around the top or free-end of the cell, spilling into the lumen of the breast ducts), that is clearly revealed by staining dyes.

Images

 mammary apocrine carcinoma

• https://twitter.com/Yalwelaie/status/732687448312971264
• https://twitter.com/AnneMillsMD/status/765893551083380736

 Wikimedia

IHC

Apocrine carcinomas tend to test negative for estrogen and progesterone receptors, but there is quite a wide variability for both hormones. Apocrine tumors have been shown to be HER-2 positive about 50% of the time, and breast cancers quite commonly test positive for androgen receptors, between 55 and 100% of the time.

 androgen receptor

• However, this subtype of triple-negative breast cancers expresses androgen receptor (AR), a feature not shared by most nonapocrine triple-negative cancers (NA-TNCs).
• AR therefore represents a potential diagnostic tool and therapeutic target for apocrine breast carcinoma.

Differential diagnosis

A diagnosis of apocrine breast carcinoma is made only after careful differentiation for other common, benign breast diseases with apocrine cell involvement. A suspected apocrine carcinoma is commonly revealed to be Apocrine Metaplasia (ACMA), a condition which quite common in younger, premenopausal women. It is a bit of a controversial issue, but there is no proven relationship between apocrine metaplasia and subsequent development of apocrine carcinoma.

See also

 mammary carcinomas
 apocrine carcinomas