Sister Mary Joseph Nodule (SMJN) is a metastatic umbilical lesion that occurs as a result of a primary malignancy affecting various organs, with the stomach and colon being the most common in men, and the ovary in women.In this article, we present a case of SMJN in an 82-year-old female patient. An urgent diagnostic workup was conducted, which included an MRI of the abdominal cavity and pelvis. The MRI revealed a large tumor located behind the uterus, along with peritoneal carcinomatosis and the presence of a nodule in the umbilical region. Following a biopsy, the morphological findings and immunohistochemical profile strongly indicated serous carcinoma of ovarian origin. This particular case highlights the challenges encountered in diagnosing SMJN based on physical examination findings, and emphasizes the importance of employing immunohistochemistry to differentiate the primary site of cancer. Gynecological malignancies should always be considered as part of the initial differential diagnosis when dealing with SMJN.