What are the other Names for this Condition? (Also known as/Synonyms)

• Giant Congenital Melanocytic Naevus
• Giant Hairy Nevus
• Nevus Pigmentosus Et Pilosus

What is Giant Congenital Melanocytic Nevus? (Definition/Background Information)

• A nevus (plural nevi) is a mole on the skin that can occur on any part of the body. A melanocytic nevus is benign tumor of melanocytic (pigment-based) cells that occur on the skin
• Congenital melanocytic nevus (CMN) is a common melanocytic mole that is present at birth, or develop immediately following birth. It may be present anywhere on the body skin, and may be classified as small, medium, and large/giant
• A Giant Congenital Melanocytic Nevus (GCMN) may be described as a very large birthmark with a diameter greater than 20 cm. Since, it may involve a large area of the body, the nevus is also variously termed as a Bathing Trunk Nevus or a Garment Nevus
• The cause of Giant Congenital Melanocytic Nevus is generally unknown, but their formation occurs during the embryological phase of development (while the baby is in the womb). Research studies have implicated certain genetic mutations as being the probable cause
• The Giant Congenital Melanocytic Nevus is typically darkly-pigmented and covers the vast areas of the trunk. The skin may be dry, itchy, and fragile. In some cases, excessive hair formation can be observed
• The Giant Congenital Nevus may undergo malignant transformations in the presence of other factors and form a malignant melanoma. Hence, a GCMN may be described as a premalignant stage to melanoma development. It is also known to be associated with other benign and malignant conditions
• The treatment for Giant Congenital Melanocytic Nevus may involve the use of topical applications (for dry and wrinkled skin) and surgery, as warranted. Since, a GCMN has an increased risk for associated malignant melanoma, it may need to be closely monitored and/or treated
• The prognosis of Giant Congenital Melanocytic Nevus is generally good in most cases, since these nevi are typically benign. However, the prognosis may depend upon other underlying conditions or the presence of a melanoma (a type of skin cancer)

Who gets Giant Congenital Melanocytic Nevus? (Age and Sex Distribution)

• The presence of a Giant Congenital Melanocytic Nevus is estimated at an incidence of 1 in every 20,000 children. It is a very rare occurrence
• Both males and females are affected; some studies show a slight female predominance
• All racial and ethnic groups are at risk and no predilection is noted

What are the Risk Factors for Giant Congenital Melanocytic Nevus? (Predisposing Factors)

The risk factors for Giant Congenital Melanocytic Nevus (GCMN) have not been clearly identified. However, an association of Giant CMN with the following have been noted:

• Neurofibromatosis, a rare genetic disorder with a familial inheritance pattern
• Presence of other nevi/moles
• Spinal cord defects at birth, such as spina bifida
• Lipomatosis, or the presence of multiple lipomas (benign tumor of fat cells)

Note: A family history of CMN is not definitely proven to be a risk factor.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Giant Congenital Melanocytic Nevus? (Etiology)

The cause of formation of Giant Congenital Melanocytic Nevus (GCMN) is presently unknown.

• Per studies, during early fetal growth and development, certain morphological errors result in the proliferation of melanoblasts (cells that are precursors to melanocytic cells)
• This may occur during the first or second trimester (between weeks 5-25), due to genetic abnormalities that may involve proto-oncogenes c-met and c-kit. Proto-oncogenes are mutated genes that may lead to cancer development
• It is reported that the earlier the overgrowth/proliferation of melanoblast cells take place, the larger and deeper will be the nevus that is formed. The later the process occurs, the smaller will be the size of CMN

What are the Signs and Symptoms of Giant Congenital Melanocytic Nevus?

The signs and symptoms of Giant Congenital Melanocytic Nevus that may be observed include:

• Usually, a large solitary nevus that involves a large extent of the skin is observed; the nevus can be of any shape and are generally asymmetrical and irregular
• The nevus may present dryness of skin (due to abnormal sweat gland function) and increased itchy sensation
• The pigmentation may be non-uniform; it may vary from dark green, brown, to black
• The texture of the nevus may be creased/wrinkled, loose-skinned, or even lumpy
• The dry skin on a nevus is generally weak; it is more prone to cracking and ulceration
• There may or may not be the presence of hair on the skin surface of the nevus; some may present excess hair (a condition known as hypertrichosis)
• Certain growth characteristics of the nevus may be more pronounced during puberty, due to hormonal influence. This may be manifested as:
  • Increase in size
  • Elevation above the surface of the surrounding unaffected skin
  • Increased pigmentation
  • Rapid hair growth on or around the nevus
• Most nevi are observed around the shoulders, back, chest, abdomen, upper arms and legs, and head and neck region
• A Giant Congenital Melanocytic Nevus will continue to grow in size as the child grows

How is Giant Congenital Melanocytic Nevus Diagnosed?

A Giant Congenital Melanocytic Nevus (GCMN) is diagnosed through the following tools:

• Complete physical examination with evaluation of medical history; a simple visual exam can help identify the presence of a nevus
• Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Skin biopsy: A skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Note:

• In many cases, no biopsy is necessary. But they may be performed to rule out other conditions presenting similar signs and symptoms
• Some CMN that are biopsied, may present atypical features on examination under a microscope by a pathologist; this may raise the suspicion of a melanoma (a type of skin cancer)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Giant Congenital Melanocytic Nevus?

A Giant Congenital Melanocytic Nevus may present the following complications:

• Scratching or itching of the moles may lead to bleeding and ulceration. This can cause secondary bacterial or fungal infections to develop
• The risk for melanoma development is increased with giant nevi. It is estimated that there is a 6-10% risk of melanoma occurrence at the site of the nevus
• Some children with giant CMN are seen to have an associated neurological abnormality (such as neurocutaneous melanocytosis) affecting the brain and spinal cord
• Severe emotional and psychological stress due to self-image issues, disfigurement, and social ostracism
• Scarring of skin following treatment
• Recurrence of the nevi; in some cases, multiple surgeries may be necessary to remove them

How is Giant Congenital Melanocytic Nevus Treated?

The treatment measures for Giant Congenital Melanocytic Nevus (GCMN) may include:

• The healthcare provider may choose to regularly observe the nevus/mole, to check for any atypical features (a “wait and watch” approach may be followed)
• Topical applications and skin moisturizers may be used for itching/burning sensations, or for dry skin
• Surgical excision of the nevus: It may be considered for large CMN presenting a potential risk for melanoma formation
• As these lesions are so large that a single procedure can only remove a portion of the GCMN. If indicated, multiple surgical sessions will be required
• A multidisciplinary team involving pediatricians, pediatric dermatologists, plastic and reconstructive surgeons, and rehabilitation specialists may be required
• Superficial skin lesions may be removed through laser therapy
• Psychological therapy to handle anxiety and stress

How can Giant Congenital Melanocytic Nevus be Prevented?

Current medical research has not established a method of preventing the occurrence of Giant Congenital Melanocytic Nevus.

What is the Prognosis of Giant Congenital Melanocytic Nevus? (Outcomes/Resolutions)

• In a majority of cases, the prognosis of Giant Congenital Melanocytic Nevus (GCMN) is good, since it is a benign condition
• However, large nevi have a higher risk for melanoma development. In such cases, the prognosis may be assessed on a case-by-case basis
• In general, the detection and treatment of melanoma arising in GCMN is usually challenging. It is also observed to metastasize more often than other cutaneous melanomas

Additional and Relevant Useful Information for Giant Congenital Melanocytic Nevus:

• Do not pick or scratch the moles
• It is important to note that a congenital melanocytic nevus does not become a melanoma with scratching, itching, or trauma. However, these should be avoided since bleeding and ulceration of skin may cause superimposed infections
• If a mole is present at birth, it is referred to as a congenital mole. If they occur in the first 2 years of life, some healthcare providers call them congenital-type moles