▶Acquired melanocytic nevi are common.
▶Begin to appear after 2 to 3 years of age.
▶Increase in number and reach a peak during the third decade.
▶Often disappear with advancing age.
▶Pigmented macules, papules, and plaques with variable surface changes
▶Sometimes classified based on appearance
■Junctional nevus: uniformly hyperpigmented (often brown) macule (Figure 68.1)
■Compound nevus: uniformly hyperpigmented (often brown) slightly elevated papule (Figure 68.2)
■Intradermal nevus: often light brown to flesh-colored and elevated (Figure 68.3)
▶Variants of acquired nevi
– Acquired nevi that develop a surrounding ring of hypopigmentation or depigmentation (Figure 68.4).
– Likely represents an immunologic response to melanocytes; often coexists with vitiligo (and may precede or follow this diagnosis).
– Nearly always benign in children; refer for evaluation if the ring of hypopigmentation is incomplete or the nevus is abnormal using ABCDE criteria (see When to Worry or Refer section).
– Nevus and hypopigmentation ultimately resolve.
– Often larger (5–12 mm) than common acquired nevi; have irregular and ill-defined borders (Figure 68.5).
– Color often is variegated with shades of brown, tan, or pink (Figure 68.6).
– Individuals who have large numbers of atypical nevi or those who have a family history of melanoma in first-degree relatives have an increased risk of developing melanoma.
■“Eclipse” nevi
– Nevus with central elevation simulating the appearance of a sunny-side up fried egg (see Figure 68.6).
– Periphery often darker compared with the lighter central portions.
– This phenotype is common on the scalps of older children and teenagers, and these nevi tend to behave in benign fashion.
Look-alikes
Disorder | Differentiating Features |
•Small, hyperpigmented macules located in sun-exposed areas such as the face, upper chest, and back. •Become darker following sun exposure. •Often fade when sun exposure is minimal. •Unlike melanocytic nevi, have no change in surface texture. •No malignancy potential. | |
•Small, hyperpigmented macules not limited to sun-exposed areas. •Unlike melanocytic nevi, have no change in surface texture. •No malignancy potential. | |
Café au lait macules | •Hyperpigmented macules that are not elevated and have no change in surface texture; most often tan in color. •Typically larger than acquired melanocytic nevi. •No malignancy potential. |
▶Benign-appearing nevi that are asymptomatic do not require removal.
▶Rapidly changing or significantly atypical nevi must be assessed for possible malignant transformation.
Treating Associated Conditions
▶Familial atypical mole/melanoma syndrome should be considered in a patient who has atypical (ie, dysplastic) moles and several family members with atypical (ie, dysplastic) nevi and at least one relative with melanoma. These patients require close surveillance to assess for the development of melanoma.
▶Ordinary acquired nevi are inconsequential; however, all nevi should be monitored for ABCDE changes (see When to Worry or Refer section).
▶Atypical nevi may imply an increased risk of the development of melanoma.
▶Melanoma is the malignant neoplasm of melanocytes that may arise de novo or from preexisting nevus. Consider the possibility of melanoma when a nevus exhibits any of the following ABCDE criteria:
■Asymmetry
■Border irregularity
■Color variation (especially red, blue, black)
■Diameter larger than about 6 mm
■Evolving lesion that is changing quickly
▶Refer patients who have atypical nevi and a family history of atypical nevi or melanoma to a dermatologist.
▶Refer patients who have atypical-appearing halo nevi (eg, those with an incomplete ring of hypopigmentation or an abnormal appearance using ABCDE criteria) to a dermatologist.
▶American Academy of Dermatology: Diseases and conditions (search options include “moles” and “melanoma”).
https://www.aad.org/public/diseases
▶Society for Pediatric Dermatology: Patient handout on moles and melanoma.
https://pedsderm.net/for-patients-families/patient-handouts/#Anchor-Moles