Breast hamartomas: clinicopathological and immunohistochemical studies of 24 cases.

Aim: The aim of our study was to investigate the clinical, pathological and immunoistochemical features of breast hamartomas, in order to obtain a detailed profile of this somewhat uncommon lesion. Methods and results: This study presents a clinical, pathological and immunohistochemical analysis of 24 breast hamartomas. Four cases of fibrocystic breast changes were used as a control group. The immunohistochemical panel induced oestrogen (ER) and progesterone (PR) receptors, c-erbB-2 protein, p53, Ki67, CK-MNF116, and vimentin. The patients ranged in age from 30 to 78 years (mean 48 years). All patients presented with a palpable unilateral mass. Three patients showed two hamartomas in the same breast. Tumours ranged from 20 to 50 mm in diameter. Typical macroscopic and microscopic features were noted. Immunohistochemical studies showed ER and PR receptor positivity in epithelial cells as well as in the stromal cells in all 24 cases. No c-erbB-2 protein over-expression was noted. p53 expression was not observed. Ki67 showed 2-3% positivity in epithelial cells and not in stromal cells in most cases. Conclusions: There was no association with side, ethnic origin or dietary habits. The immunohistochemistry of hamartomas is generally similar to normal breast or fibrocystic breast tissue. Ki67 together with receptor positivity may reflect some proliferative activity and explain observed faster growth of hamartoma during pregnancy and lactation.