Compound Melanocytic Nevus

Compound Nevi

Key points

Compound Nevi are a sub-class of Common Acquired Melanocytic Nevi
Typically they are light tan to dark brown, dome shaped papules that are 1-10 mm in diameter.
Compound Nevi are benign proliferations of melanocytes at the epidermal-dermal junction.
Common finding in all people, however increased numbers of nevi increase risk for developing melanoma

Compund nevi present as smooth, dome shaped papules or small nodules that are <10 mm in diameter. Their coloring varies from light tan to dark brown. Compound nevi have regular, well demarcated edges and may have terminal hairs. They are generally smooth, but may appear as hyperkarotic (thickened stratum corneum) plaques or may be papillomatous (wart like appearance). Compound Nevi typically appear in childhood and adolescents and begin to regress in adulthood.

There are three types of common acquired melanocytic nevi, Junctional nevi, Compound Nevi, and Intradermal Nevi. As we age, melanocytes migrate down through the layers of the skin starting with the epidermis, down to the epidermal-dermal junction and finally into the dermis. This creates an evolution of the nevi from junctional to compound to intradermal. As melanocytes move down through the layers of skin they begin to lose their ability to produce pigmentation (melanin). For example, intradermal nevi should have least amount of pigment and resemble the color of flesh because they are deeper in the skin. This loss of pigment, in a general sense, also aligns with the age in which these different nevi appear; Junctional nevi in early childhood, compound nevi in childhood to early adulthood, and intradermal nevi by the third or fourth decade. Compound nevi are found at the epidermal-dermal junction. Therefore, they have components of both junctional and intradermal nevi. They have significant amounts of pigment, like junctional nevi, and they are raised papules, like intradermal nevi.

In childhood, compound nevi may appear anywhere on the body especially sun exposed areas such as the legs, neck, head, and trunk. In adulthood, they are more likely to appear on the palms, soles, and the genital region. Compound nevi that appear in late adulthood are at increased risk for being malignant. Individuals with lighter skin typically have more compound nevi and there is no difference in their prevalence between the sexes.

Differential diagnosis

Seborrheic Keratosis
Dermatofibroma
Atypical Nevus
Spitz Nevus
Blue Nevus
Melanoma
Atypical Nevus

Diagnosis

Key points

Clinical presentation is the most important aspect of diagnosis
Histologic examination confirms diagnosis

Diagnosis is primarily made by history and clinical presentation. When the clinical picture is murky, a complete excisional biopsy and histopathologic evaluation of the mole is made to rule out melanoma. The histologic findings of small, uniform, symmetrical, well circumscribed nests of melanocytes are reassuring for melanocytic nevi.

Treatment

Key points

In most cases moles do not require treatment
Suspicious moles should be removed and examined
Prevent skin damage from sun exposure

Melanocytic Nevi are, by definition, benign and most moles remain benign throughout a person’s lifetime. Therefore, most moles will never need to be treated. However, suspicion that a mole may be a melanoma, a change in the size, shape, or pigmentation of the mole, chronic irritation, or cosmetic concerns are reasons that the melanocytic nevi may be removed via excisional biopsy. When this is performed, if possible, the entire lesion should be removed and undergo histologic evaluation to rule out malignancy.

It is important for individuals who have a significant number of nevi to have counseling about the dangers of excessive sun exposure, skin protection, and to undergo periodic total skin inspections by a dermatologist.

References

Rooks Textbook of dermatology
Clinical Dermatology
General Dermatology
www.emedicinemedscape.com
www.up-to-date.com
www.dermnetz.org
www.ncbi.nlm.nih.gov