The umbilical clue: recognizing Sister Mary Joseph Nodule

Abstract Sister Mary Joseph’s nodule (SMJN) is a rare manifestation of intra-abdominal malignancy presenting as a metastatic umbilical lesion. We report the case of an 82-year-old woman with no prior medical history who presented with asthenia, weight loss, and a violaceous, ulcerated umbilical lesion. Imaging revealed peritoneal carcinomatosis, pelvic lymphadenopathy, and a suspicious endometrial mass. Pelvic MRI identified a heterogeneous lesion within the endometrial cavity suggestive of neoplasia. Transvaginal ultrasound and hysteroscopy confirmed a friable, polypoid endometrial mass. Biopsies of both the cutaneous and endometrial lesions identified a serous endometrial adenocarcinoma with umbilical metastasis, confirmed by immunohistochemical markers (CK7+, PAX8+, CK20−, CDX2−). Given the extent of lymphatic and peritoneal spread, the patient was referred to palliative care. SMJN accounts for approximately 10% of cutaneous metastases and often signifies advanced disease with a poor prognosis. Although rare, it may be the first visible sign of a hidden malignancy. This case highlights the importance of considering SMJN in differential diagnoses of umbilical lesions and underscores the need for prompt investigation to determine the underlying pathology. Early recognition can aid in appropriate management, although treatment is typically palliative due to the advanced stage at diagnosis.