[A Case of De Novo Stage Ⅳ Breast Cancer with Umbilical Metastasis and Peritoneal Dissemination].

The patient was a 48-year-old woman. At the time of consultation, a hard mass of 30 mm in size was palpated in area A of the right breast, and a firm mass of about 10 mm was seen in the umbilical region. Histological diagnosis of the breast mass was invasive ductal carcinoma. PET-CT scan showed accumulation in the right breast, as well as suspicion of umbilical metastasis and peritoneal dissemination, uterine mass, and left ovarian cancer. Since this is an atypical metastatic site for invasive ductal carcinoma of the breast, and the possibility of peritoneal dissemination due to gynecological cancer complications cannot be ruled out, resection of the umbilical mass and laparoscopy was performed. The review laparoscopy revealed no evidence of primary cancer in the uterine body or left ovary, and a white nodular lesion of suspected seeding in the peritoneum around the left ovary. The histology and immunostaining results of the umbilical mass and left peri-ovarian nodule both showed glandular luminal structures similar to those of the primary breast cancer, and the left peri-ovarian nodule was ER positive, GATA3 positive, and PAX8 negative, leading to the diagnosis of umbilical metastasis and peritoneal seeding derived from breast cancer. Umbilical metastasis is often referred to as Sister Mary Joseph's nodule in the case of visceral malignancies and is often associated with peritoneal dissemination and is often caused by invasive metastasis of peritoneal dissemination lesions on the dorsal side of the umbilical region. In this case, histological examination of the umbilical specimen showed no disseminated lesion on the peritoneal side, so it was not considered to be an invasive metastasis due to peritoneal dissemination.