A 45 year old female presented with a new group of suspicious calcifications on screening mammogram
Contributed By: Kamaljeet Singh MD
- Tubular carcinoma
- Flat epithelial atypia
- Apocrine mtaplasia
- Atypical ductal hyperplasia
- Columnar cell change/hyperplasia
The answer is: Flat epithelial atypia
Flat epithelial atypia
Low magnification reveals variably dilated ducts, some with floccular secretions and phosphate type basophilic calcifications. The lining epithelium is monomorphic and appears to have multiple layers of cells with slightly enlarged (low nuclear grade) rounded nuclei. The luminal surface displays cytoplasmic extensions/snouts and cells contain moderate eosinophilic cytoplasm. No overt mitotic activity, necrosis or cellular debris is noted. Intraductal epithelial proliferation is lacking structures like micropapillae, cellular bridges or arcades (flat). Myoepithelial cells are appreciated, however they are inconspicuous. The periductal stroma shows scattered minimal lymphoid infiltrate and there is no desmoplasia.
The histological diagnosis is flat epithelial atypia (FEA).
FEA falls within the spectrum of so-called columnar cell lesions of breast that show low-grade cytologic atypia (aka columnar cell change/hyperplasia with atypia). FEA is terminal duct lobular unit based lesion which can be a target lesion in a biopsy performed for calcifications. Their etiology is speculated to be similar to other low-grade breast neoplastic lesion (like ADH and LCIS) and they are considered as earliest stage of low-grade breast neoplasia and likely represent non-obligate precursor to ADH and DCIS.
FEA management needs radiological-pathological correlation. The upgrade rate of FEA on excision is lower than ADH. Observation may be considered if postbiopsy mammogram reveals absence of residual calcifications.
Reference: Reference: WHO classification of Tumours Editorial Board. Breast tumours. Lyon (France): IARC; 2019 (pages 15-17).