Breast - nonmalignant
Apocrine adenosis

Author: Jaya Ruth Asirvatham, M.B.B.S., M.D. (see Authors page)
Editor: Julie M. Jorns, M.D.

Revised: 2 August 2017, last major update December 2014

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Apocrine adenosis [title]

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Cite this page: Apocrine adenosis. website. Accessed December 19th, 2018.
Definition / general
  • Defined as the presence of apocrine cytology in a recognizable lobular unit associated with sclerosing adenosis (J Clin Pathol 2007;60:1313)
Atypical apocrine adenosis
  • Defined as 3 fold variation in nuclear size
  • Uncommon lesion
  • Average age of women is 59 years
  • A study of 37 patients showed no increased risk for carcinoma, as previously suggested (Arch Pathol Lab Med 2012;136:179)
Microscopic (histologic) description
  • Cells with apocrine metaplasia have abundant eosinophilic cytoplasm with bright eosinophilic granules that are PAS positive
  • The apocrine cells have round nuclei and may show nuclear pleomorphism ( > 3 fold in atypical variant); a central eosinophilic nucleolus is generally seen
  • Rare multinucleation may be observed and is not considered atypical
  • Rare to no mitosis
  • No necrosis
  • Can be associated with radial scars
Microscopic (histologic) images

Images hosted on PathOut server:

AFIP images:

Circumscribed lesion

Appears infiltrative

Ducts lined by
apocrine cells with
large nuclei and
prominent nucleoli

Cells have vacuolated
cytoplasm, large nuclei
and prominent nucleoli

Images hosted on other servers:

Within a lobule

Expansion of lobular units with marked apocrine metaplasia ("B" is low power location)

With sclerosing adenosis


Highly cellular and tumefactive growth pattern

Androgen receptor positive

With atypia, contributed by Dr. Semir Vranic

With atypia: 3x variation in nuclear size

Cytology description
  • Often highly cellular
  • Cells have apocrine metaplasia with prominent nucleoli and pleomorphism, possibly resembling carcinoma but minimal hyperchromasia
  • Naked nuclei are present (Diagn Cytopathol 2007;35:296)
Negative stains
Electron microscopy description
  • Distinct basal lamina present
Differential diagnosis
  • Apocrine carcinoma: malignancy should be obvious
  • Cancerization of lobule by apocrine DCIS: architectural patterns of DCIS typically also present (e.g. comedo, cribriform, etc.); mitosis and necrosis usually identified
  • Microglandular adenosis: glands are smaller, more regular; no myoepithelial cells
  • Tubular adenosis: haphazard proliferation of elongated tubules