Atypical nevus in Child
There is controversy around the term dysplastic nevus, including a lack of consensus on how it is defined and what it represents biologically. Originally described in melanoma-prone families, dysplastic nevi were part of a clinical phenotype. Patients characteristically had numerous nevi, which often appeared clinically atypical; on biopsy (as initially described by Dr. Wallace Clark), 4 main histologic features were observed: 1) atypical melanocytic hyperplasia, 2) melanocytes with cytologic features characteristic of malignant melanocytes, 3) mesenchymal changes in the papillary dermis, and 4) lymphocytic infiltrate. Since then, dysplastic nevi have been recognized to occur spontaneously, and different variations of the above diagnostic criteria (including grading of cytologic atypia as mild, moderate, or severe) have been proposed without a clear diagnostic consensus.
Dysplastic nevi usually begin to appear in childhood through early adult years and have an estimated prevalence ranging from 2%-10%. The incidence of histologically proven dysplastic nevi is estimated at 2.2% in children aged younger than 12 years and 1.3% in adolescents. More atypical nevi usually begin to appear around puberty. They are thought to have a genetic component and are more common in phototype I-III individuals. While less prevalent than common nevi, dysplastic nevi are believed to correlate with the overall number of melanocytic lesions in an individual and are thought to confer a 4- to 15-fold increased risk of melanoma.
While there is an increased relative risk of melanoma in individuals with multiple dysplastic nevi and dysplastic nevi can share clinical and histologic features with melanoma, current evidence does not support a dysplastic nevus as a definite premalignant lesion. Studies have shown that most melanomas appear to arise de novo without an associated nevus, and even when an associated nevus is present in histologic contiguity with melanoma, it is more frequently a common nevus than a dysplastic nevus.
Related topic: agminated nevus
D23.9 – Other benign neoplasm of skin, unspecified
254818000 – Atypical nevus of skin
Differential Diagnosis & Pitfalls
- Congenital nevus
- Spitz nevus – Solitary; pinkish, tan, or red-brown; smooth-surfaced; dome-shaped papule, often with surface telangiectasia.
- Common nevus
- Ephelides (freckles)
- Supernumerary nipple
- Lentigo simplex
- Traumatic tattoo
- Blue nevus
- Combined nevus (blue nevus and compound nevus together)