How is papillary apocrine metaplasia differentiated from small, peripheral intraductal papilloma (IDP)?

Updated: Dec 25, 2019
  • Author: Joshua I Warrick, MD; Chief Editor: Chandandeep Nagi, MD  more...
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Answer

Answer

Papillary apocrine metaplasia is encountered in the epithelium of cysts and is quite distinctive. The key to making the diagnosis lies in identifying the diffuse apocrine change in the epithelium, which has a characteristic intense eosinophilia (see the images below). Nucleoli are also often prominent. Fibrovascular cores in papillary apocrine metaplasia are delicate or absent, and the cell apices may show classic apocrine decapitate secretions.

Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Papillary apocrine metaplasia (100×). The cells have abundant pink cytoplasm. The papillary processes have no fibrovascular cores in this example.
Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Same papillary apocrine metaplasia as in the previous image (200×).

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