Background: Umbilical metastasis, also known as Sister Mary Joseph nodule, is a rare pathognomonic clinical sign suggesting the presence of an internal cancer. Case Presentation: We describe two female patients with Sister Mary Joseph nodule. In one case, there was a relapse of cancer. In the other patient, the Sister Mary Joseph nodule was the first and only clinical sign of an abdominal malignancy. We will briefly discuss the association with various internal malignancies as well as the pathogenesis and differential diagnosis. Conclusion: We conclude that Sister Mary Joseph nodule is a sign of intra-abdominal malignancy most frequently associated with gastro-intestinal or gynecological cancer. It can be the first and only clinical sign of abdominal malignancy in an otherwise healthy appearing patient or it can be an indication of oncological progressive disease, tumor relapse. Umbilical lesions should raise suspicion of a Sister Mary Joseph nodule, but a differential diagnosis must be made with other primary umbilical malignancies as well as with benign conditions involving the umbilicus.

Keywords: Sister Mary Joseph nodule, metastasis, umbilicus, gastric signet cell adenocarcinoma, ovarian serous papillary adenocarcinoma