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Giant congenital nevus

Congenital giant pigmented nevus; Giant hairy nevus; Giant pigmented nevus; Bathing trunk nevus; Congenital melanocytic nevus - large

 

A congenital pigmented or melanocytic nevus is a dark-colored, often hairy, patch of skin. It is present at birth or appears in the first year of life.

A giant congenital nevus is smaller in infants and children, but it usually continues to grow as the child grows. A giant pigmented nevus is larger than 15 inches (40 centimeters) once it stops growing.

Causes

 

These marks are thought to be caused by problems with melanocytes that don't spread evenly as a baby grows in the womb. Melanocytes are the skin cells that produce melanin, which gives skin its color. A nevus has an abnormally large amount of melanocytes.

The condition is thought to be caused by a gene defect.

The condition may occur with:

  • Growth of fatty tissue cells
  • Neurofibromatosis (an inherited disease involving changes in skin pigment and other symptoms)
  • Other nevi (moles)
  • Spina bifida (a birth defect in the spine)
  • Involvement of the membranes of the brain and spinal cord when the nevus affects a very large area

Smaller congenital pigmented or melanocytic nevi are common in children and do not cause problems most of the time. Larger or giant nevi are rare.

 

Symptoms

 

A nevus will appear as a dark-colored patch with any of the following:

  • Brown to bluish-black color
  • Hair
  • Regular or uneven borders
  • Smaller affected areas near the larger nevus (maybe)
  • Smooth, irregular, or wart-like skin surface

Nevi are commonly found on the upper or lower parts of the back or the abdomen. They may also be found on the:

  • Arms
  • Legs
  • Mouth
  • Mucus membranes
  • Palms or soles

 

Exams and Tests

 

You should have all birthmarks looked at by a health care provider. A skin biopsy may be needed to check for cancer cells.

An MRI of the brain might be done if the nevus is over the spine. A giant nevus on the spine may be linked to brain problems.

Your provider will measure the dark skin area every year and may take pictures to check if the spot is getting larger.

 

Treatment

 

You will need to have regular exams to check for skin cancers.

Surgery to remove the nevus can be done for cosmetic reasons or if your provider thinks it may become skin cancer. Skin grafting is also done when needed. Larger nevi may need to be removed in several stages.

Lasers and dermabrasion (rubbing them off) can also be used to improve appearance. These treatments may not remove the whole birthmark, so it may be harder to detect skin cancer (melanoma). Talk to your doctor about the pros and cons of surgery for you.

Treatment may be helpful if the birthmark causes emotional problems because of how it looks. 

 

Outlook (Prognosis)

 

Skin cancer may develop in some people with large or giant nevi. The cancer risk is higher for nevi that are larger in size. However, it isn't known if removing the nevus reduces that risk.

 

Possible Complications

 

Having a giant nevus may lead to:

  • Depression and other emotional problems if the nevi affect appearance
  • Skin cancer (melanoma)

 

When to Contact a Medical Professional

 

This condition is usually diagnosed at birth. Talk to your child's provider if your child has a large pigmented area anywhere on their skin.

 

 

References

Habif TP. Nevi and malignant melanoma. In: Habif TP, ed. Clinical Dermatology. 6th ed. Philadelphia, PA: Elsevier; 2016:chap 22.

Hosler GA, Patterson JW. Lentigines, nevi, and melanomas. In: Patterson JW, ed. Weedon's Skin Pathology. 4th ed. Philadelphia, PA: Elsevier; 2016:chap 32.

 
  • Congenital nevus on the abdomen

    Congenital nevus on the abdomen - illustration

    Congenital nevi are present at birth and may range in size from less than one centimeter to the giant "bathing trunk" nevus, which covers a large area of the body. Skin texture may range from normal to raised, nodular to irregular, and they are frequently darkly pigmented. Melanomas may develop more easily in congenital nevi.

    Congenital nevus on the abdomen

    illustration

    • Congenital nevus on the abdomen

      Congenital nevus on the abdomen - illustration

      Congenital nevi are present at birth and may range in size from less than one centimeter to the giant "bathing trunk" nevus, which covers a large area of the body. Skin texture may range from normal to raised, nodular to irregular, and they are frequently darkly pigmented. Melanomas may develop more easily in congenital nevi.

      Congenital nevus on the abdomen

      illustration

    A Closer Look

     

      Self Care

       

        Tests for Giant congenital nevus

         

           

          Review Date: 10/24/2016

          Reviewed By: David L. Swanson, MD, Vice Chair of Medical Dermatology, Associate Professor of Dermatology, Mayo Medical School, Scottsdale, AZ. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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