Invasive lobular carcinoma in a hypoplastic breast

Breast hypoplasia is encountered as part of genetic syndromes or as a result of iatrogenic factors. The incidence of this malformation and the occurrence of breast carcinoma in such cases are unknown. The authors present a 66-year-old patient with a severe breast hypoplasia and invasive lobular carcinoma. The advanced clinical stage required neoadjuvant chemotherapy. After 5 CMF cycles with no significant effect, a modified radical mastectomy with axillary lymph node dissection was performed. The pathological report revealed an infiltrating lobular carcinoma with combined classical and alveolar growth and with minor morphological changes after the chemotherapy. Immunostaining for cell proliferation markers, apoptotic regulators, and cell adhesion molecules, such as the CD44 family and members of the cadherin-catenin group, was performed. The tumor expressed a high bcl-2/low bax ratio and lacked p53 immunoreactivity, which could explain the resistance to neoajuvant therapy. The lack of adhesion molecules, except for strong E-cadherin and beta-catenin reactivity, and weak CD44v6 expression were demonstrated. To the authors' knowledge this is the first case of an invasive lobular carcinoma in a hypoplastic breast reported in the English literature.