An otherwise healthy 45-year-old woman consulted for an umbilical lesion that had first appeared 4 months earlier. The lesion was excrescent, asymptomatic, and with no evident fluctuations in size or bleeding. The patient had regular menstrual periods and complained only of dysmenorrhea. The physical examination revealed a well-defined, hard, brown nodular lesion measuring 15mm that did not adhere to deep planes (Fig. 1A). Dermoscopy revealed a round lesion with clear borders, homogeneous violaceous pigmentation, and a white reticular pattern in the central area (Fig. 1B). The results of histopathology indicated cutaneous endometriosis.

Figure 1

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Cutaneous endometriosis is an unusual presentation of endometriosis. When it manifests as an umbilical nodule, it is traditionally known as Villar nodule. It typically takes the clinical form of a nodular lesion on a surgical scar, its size fluctuates, and it bleeds in line with the menstrual cycle. Dermoscopy findings can range from a polymorphous vascular pattern over a milky-red or violaceous background to the absence of vascular structures on a bluish background with brown areas. In the present case, we observed a previously undescribed pattern involving a central white reticular pattern over a bluish background. Therefore, the main differential diagnosis should be with aneurysmal dermatofibroma, although the Sister Mary Joseph nodule should also be taken into account. Diagnosis should be confirmed with a histopathology workup. The treatment of choice is surgery, and prognosis is excellent.