Abstract
Cystic hypersecretory lesions of the breast are a spectrum of conditions ranging from cystic hypersecretory hyperplasia with atypia and invasive cystic hypersecretory carcinoma (CHC). It is a subtype of ductal carcinoma of the breast. The tumour is very infrequent and hence, extensive literature is limited. This culminates in the fact that it does not feature as part of the WHO classification of breast tumours. However, a good knowledge about its distinct pathological features can avert misdiagnosis and help differentiate CHC from other conditions. Thus far, only 22 cases of invasive CHC have been reported, of which 3 were microinvasive. Only 7 cases of axillary lymph node metastasis have been documented. We report a case of invasive CHC of the breast that was metastatic to the axilla and refractory to neoadjuvant chemotherapy. Our case report aims to add to the literature on the disease, aiming to support large-scale studies in the future in order to elaborate on its clinical and biological characteristics.