Introduction: Pregnancy-associated breast cancer is defined as the malignant mammary lesion appearing during pregnancy or within the first year after delivery. In this paper we present a case of pregnancy-associated breast cancer and review current options for diagnosis and treatment. Case presentation: Thirty two year old woman with onset of breast mass in her fourth week pregnancy. The diagnosis of breast cancer was established at week 12, and began neoadjuvant therapy until week 20 with no response. Modified radical mastectomy was performed at week 32 without effects on the fetus, or maternal complications. Discussion: Pregnancy-associated breast cancer is the second most common malignant tumor during pregnancy; the diagnosis is often delayed, a fact that impairs prognosis due to advance in stage. The goals of treatment are the same for non-pregnant women: local control of the malignant tumor and prevention of systemic spread. It is unclear whether pregnancy is an independent adverse risk factor for outcomes in pregnancy-associated breast cancer. Conclusions: Current evidence is insufficient to define the best treatment options for breast cancer associated with pregnancy.