What's Your Next Step?
Bathing trunk nevus
Definition
A bathing trunk nevus is a dark colored, often hairy patch of skin that is present at birth.
Alternative Names
Congenital giant pigmented nevus; Giant hairy nevusCauses
Bathing trunk nevi are thought to be caused by defects or problems that occur as a baby grows in the womb. However, in some families bathing trunk nevus may be inherited.
Bathing trunk nevus may occur with:
- Growth of fatty tissue cells (lipomas)
- Neurofibromatosis
- Other nevi
- Spina bifida
The risk of this condition is thought to be 3 - 7%.
Symptoms
- Dark-colored patch of skin covering a large area of the middle body or arms and legs
- Brown to bluish-black color
- May contain hair
- Skin may be smooth to wart-like
Exams and Tests
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
Treatment consists of surgery to remove the nevus. Skin grafting is done when necessary. Extremely large nevi may be removed in several stages. Although surgical removal is the treatment of choice, lasers can also be used to improve the appearance.
Steroid medications may be used, but they can have side effects.
Psychological treatment can help with the emotional impact of having a disfiguring disorder.
Outlook (Prognosis)
Bathing trunk nevi are not serious, unless the nevus turns into skin cancer (malignant melanoma).
Possible Complications
- Depression and other emotional problems (due to appearance)
- Skin cancer (melanoma)
Rarely, bathing trunk nevi occur with a condition that causes a growth of pigment-producing cells in the head (leptomeningeal melanocytosis). Complications include:
- Hydrocephalus
- Motor abnormalities
- Seizures
When to Contact a Medical Professional
This condition is usually diagnosed at birth. Call for an appointment with your health care provider (or mention it during a well-baby exam) if your child has a large pigmented area anywhere on the skin.
Reviewed By: Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.




