Apocrine Carcinoma of the Breast

Definition

Breast carcinoma with abundant eosinophilic cytoplasm, large round nuclei and sharp cell borders

Clinically significant criteria have not generally been agreed upon
- Most describe some degree of abundant eosinophilic cytoplasm, sharp cell borders, round nuclei and prominent nucleoli
- Some simply refer to GCDFP15 positive carcinomas as apocrine
Japaze 2005 has proposed the following criteria:
- At least 75% of microscopic fields must demonstrate the following features:
  - Large cells with abundant eosinophilic cytoplasm
    - Usually granular
  - Nucleus to cytoplasm ratio of 1:2 or more
  - Nuclei round, large and vesicular
    - May be pleomorphic
  - Sharply defined cell borders
- Minor (non-mandatory) criteria
  - Prominent nucleoli in >50% of fields
  - Apical cytoplasmic snouts into lumenal spaces
- Japaze 2005 reported significantly improved survival when apocrine carcinomas were defined as above

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342