Atypical Apocrine Adenosis
Epidemiology and Etiology:
Common sites:
Gross features:
Histologic features:
- Apocrine cells:
- Abundant granular, eosinophilic cytoplasm (type
A cells)
- Apical luminal blebbing
or snouting and distinctive cell membranes
(sometimes)
- Foamy cytoplasm with small vacuoles that may
coalesce (type B cells)
- Round nuclei varying in size with vesicular
chromatin and conspicuous nucleoli
- PASD+
- Loss of myoepithelial cells around benign and
neoplastic apocrine lesions is well documented
- Atypical apocrine proliferations:
- Architecture:
- Stratified
- Tufts without epithelial bridges
- If epithelial bridges or cribriform pattern,
not entire duct involved, or < 2 mm
- Not filling ducts (this would meet criteria
for apocrine DCIS
- Cytology:
- 3-fold nuclear enlargement, prominent
- multiple pleomorphic nucleoli
- nuclear hyperchromasia
- irregularities of the nuclear membrane
- cytoplasmic vacuoles / foamy cytoplasm
- mitotic figures
- no necrosis
(DCIS)
- ADH with apocrine features:
- Rigid arches
- Cribriform spaces
- Bulbous papillae
-
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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EMA
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CK8/18
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ER (neg)
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PR (neg)
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AR
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GCDFP
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CK5/6
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Variable
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e-cadherin
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Molecular features:
Other features:
- Too rare for determining risk of subsequent
malignancy
References:
- Asirvatham
JR, Falcone MMG, Kleer CG. Atypical apocrine adenosis:
diagnostic challenges and pitfalls.
Arch Pathol Lab Med 2016;140:1045-1051.