Table 1.

Differential diagnosis of an umbilical nodule.

Benign	Malignant
Cutaneous endometriosis/endosalpingiosisa	Sister Mary Joseph nodeb
Haemangioma/vascular malformation	Melanoma
Umbilical hernia/cicatrical hernia	Sarcoma
Sebaceous cyst	Adenocarcinoma
Granuloma Lipoma Abscess Keloid Omphalomesenteric or urachus anomaly and/or infection Desmoid tumour	Lymphoma

^aEndosalpingiosis: the presence of fallopian tube-like epithelium outside of the fallopian tube.

^bSister Mary Joseph node: palpable nodule bulging into the umbilicus as a result of metastasis of a malignant tumour in the pelvis or abdomen.