Bathing trunk nevusA bathing trunk nevus is a congenital (present from before birth), disfiguring, darkly pigmented, often hairy patch of skin (nevus), which may cover an extremely large area of the body. Sometimes the nevus covers most of the trunk, the upper arms, and thighs. Bathing trunk nevi are thought to be caused by spontaneous mutations or other events during fetal
development, but in some families, the frequent appearance of these lesions suggests that they may be genetically inherited. They may be associated with other birth defects. The surface texture may vary from smooth to warty, and the color varies from brown to bluish black. Bathing trunk nevi may cause emotional problems because of their appearance.
Symptoms of a bathing trunk nevus may include: • a brown molelike birthmark covering an extensive area of the trunk or legs • color varying from brown to blue-black • hair growing from the mole • smaller lesions near the large mole • surface texture varying from smooth to warty.
All birthmarks should be evaluated by your health care provider. A biopsy of suspicious areas may be obtained for examination to determine if the cells have become cancerous. An MRI of the brain might be performed. Treatment consists of surgery to remove of the nevus, with skin grafting where necessary. Extremely large nevi may be removed in several stages. Psychological treatment may be needed to deal with the emotional impact of having a disfiguring disorder.
A bathing trunk nevus may develop into melanoma, a particularly serious form of skin cancer. The cosmetic appearance may cause psychosocial problems.