Apocrine metaplasia of the breast

Apocrine metaplasia of the breast, also apocrine metaplasia, is a benign change in the breast without increased risk of malignancy.

General

• Benign/not significant. Can be considered to be pretty wallpaper in the house of breast pathology.
• Very common in adults.
• Apocrine lesions as a group are usually benign, some pre-neoplastic and some malignant.

Etiology

• Increased number of mitochondria.
  • In other body sites this has different names, e.g. Hurthle cell change (thyroid), oncocytic change (kidney - oncocytoma, thyroid).

Microscopic

Features:

• Eosinophilic cytoplasm - key feature.
• Voluminous pink cytoplasm.
• Apocrine snouts may be present.
  • Small protrusiona at the apical aspect of the cell (composed of cytoplasm and plasma membrane).
• Central round nucleus
  • Prominent nuclear membrane.
  • Prominent, often single nucleolus.

Note:

• Apocrine changes, i.e. cytoplasmic eosinophilia, can appear in malignant tumours; eosinophilia doesn't make something benign.

Images

• 

  FCC with apocrine metaplasia (right bottom of image) - high mag. (WC/Nephron).

• 

  Breast - Apocrine Change - high power (SKB)

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• Typically not reported.

See also

• Oncocytoma.