[Black tumor of the umbilicus]

Pigmented nevi, still called melanocytic nevi or more improperly "naevus naevocellulaires" are benign melanocytic tumors characterized by a proliferation of melanocytes near the dermoepidermal junction. They are grouped in clusters or in theca cells that differentiate them from normal melanocytes. They occur at birth in approximately 1% of newborns with no sex predominance. Their occurrence is mostly sporadic, although rare family forms have also been reported. They can be separated in an arbitrary manner according to their diameter on the day of the birth: small congenital nevi <1.5cm, medium-sized 1.5 to 20cm and large-sized >20cm. Umbilical nevi are rare. We here report an interesting case of atypical and rare congenital nevus. The study involved a young girl presenting with pigmented umbilical nodule occurred at birth which had recently become problematic. We suspected a nevus, a melanoma or an endometriosis on the basis of the clinical appearance of this nodule. Resection was performed. The diagnosis of benign melanocytic tumor was confirmed.