Abstract
Breast undergoes hormonal changes, especially during pregnancy and postpartum period and may be associated with benign and malignant lesions. These lesions can arise either de novo or can be an exacerbated change occurring in a preexisting breast lesion. The benign lesion in the lactating breast can show some degree of atypia due to the high levels of progesterone and prolactin which can mimic malignant features microscopically and can be overdiagnosed with breast cancer. On the other hand, breast cancer in the lactating breast can be underdiagnosed when the atypical cytological features are considered as hormonal changes. A few case reports are published in the literature regarding lactating adenoma undergoing malignant transformation. We present a case in 23 years postpartum lactating female with mass in bilateral breasts. Initially, the lesions were diagnosed with hormonal changes on cytology. On follow-up by fine-needle aspiration cytology and biopsy, it was diagnosed with infiltrating ductal carcinoma in both breasts. As far as our knowledge goes, this is the first-case report in the English literature of ductal carcinoma in the bilateral lactating breast arising de novo.