Bathing trunk nevus encased in tumorous growth on body − an eccentric entity!

Giant melanocytic nevoid lesions, over 20 cm in diameter, are referred to as ‘bathing trunk nevi’ or ‘giant congenital melanocytic nevus (CMN)’, and have an incidence of 1 in 2,00,000 to 1 in 5,00,000 neonates. Diffuse lipomatosis, von-Recklinghausen’s disease, neurocutaneous melanosis and malignant melanoma are a few serious pathologies that are sometimes linked to these lesions. They begin as dark brown to black patches with a smooth or rugose surface, hair-covered, clearly defined boundaries and frequently associated sporadic satellite lesions. Between the 5th and 25th week of pregnancy, melanocytes of neuroectodermal origin may accumulate ectopically and cause these lesions. A multitude of histological elements, such as neuronal, lipomatous or any other, may be linked to giant CMN. The fact that these lesions are a progeny of pluripotent stem cells, which have the ability to develop into a variety of cell types, justifies this finding. Patients and their families have severe aesthetic and psychological concerns about these enormous pigmented nevi.