Primary umbilical endometriosis - Diagnosis by fine needle aspiration

Primary (spontaneous) umbilical endometriosis is very rare with an estimated incidence of 0.5-1% of all patients with endometrial ectopia. Endometriosis is a common gynecological condition, the pelvis being the most common site of the disease. Extrapelvic site is less common and even more difficult to diagnose due to the extreme variability in presentation. A 38-year-old woman presented with a blackish nodule over the umbilicus of 3 years duration. Fine needle aspiration cytology of the lesion showed cells in clusters and sheets with background of scant stromal fragment, hemosiderin laden macrophages and RBCs, leading to a suggestion of umbilical endometriosis. Histopathological examination of the excised lesion confirmed the same.