Mucinous cystadenocarcinoma of breast in a 69-year-old woman with positive hormone receptors, the first case reported

BACKGROUND: Mucinous cystadenocarcinoma is a relatively uncommon histological subtype of breast cancer that is a cystic form of papillary mucinous carcinoma. It is regularly negative for estrogen and progesterone receptors and it is most often diagnosed in older than 55-60 years old. The incidence of breast mucinous cystadenocarcinoma is about 1-6% of primary breast cancers. Here, we present a case of breast mucinous cystadenocarcinoma of left breast in a 69-year-old female which is positive for estrogen and progesterone receptors. CASE PRESENTATION: In this article, we describe a case of a-69-year-old female with a painful mass in her left breast. Based on intraoperative pathology consult, neoplastic tissue mostly floating in mucinous lakes with invasion to surrounding stroma was seen. Immunohistochemistry profile showed positive estrogen and progesterone receptors and negative for HER2. CONCLUSION: Mucinous cystadenocarcinoma of breast is typically triple negative for hormone receptors. But ER and PR positive variant of this tumor is rare, giving the chance of a better prognosis for the patient with hormonal therapy.