Congenital Nevi Differential Diagnoses

Updated: Apr 05, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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DDx

Diagnostic Considerations

Also consider the following:

The histopathologic interpretation of proliferative nodules (PNs) in congenital melanocytic nevi can be challenging, as some PNs may exhibit atypical features that make the distinction from melanoma difficult. [30] Histologic features and Ki-67 and PHH3 expression levels were found to be the best parameters to distinguish between benign versus atypical PNs, which appear to be borderline between benign PNs and dermal melanomas. It can be difficult to differentiate between benign and malignant proliferation in infants with secondary melanocytic proliferation. [31] Giant congenital melanocytic nevi with solid tumors within them presenting at birth are unusual; a variety of malignancies may occur within these masses. [32, 33]

The BRAF V600E mutation may be the most common oncogene and precursor in melanoma, so its presence in a congenital nevus is of concern. [34] A giant congenital melanocytic nevus with vascular malformation and epidermal cysts, associated with a somatic activating mutation in BRAF, has been described. [35]  Nevus-associated melanoma, the coexistence of melanoma and nevus components, results from melanomas developing on preexisting congenital or acquired nevi; these are usually of the superficial spreading subtype and have the BRAFV600E mutation. [36]

Differential Diagnoses