Small Congenital Nevi Associated with Melanoma: Case Reports and Considerations

Abstract

Melanocytic nevi, both congenital and acquired, are considered to be precursors of melanomas. Data about the malignant potential of these nevi are conflicting, particularly with reference to the nevus of the smallest size. Patients with preexisting melanocytic nevi (both congenital and acquired) have risks of developing melanoma that differ from those of subjects without them. The purpose of this study was to verify the presence of melanoma in preexisting nevi both congenital (congenital nevus associated melanoma) (CNAM) and acquired (ANAM). In particular, we investigated melanomas associated with small congenital nevi (SCN). A cohort of 190 patients with primary melanomas was studied. Congenital nevi were called "small" (SCN) when their diameters were less than 1.5 cm. Epiluminescence microscopy (ELM) was performed to further improve the clinical diagnosis and to observe the more subtle changes in the preexisting nevi. Forty of the 190 cases of melanoma were associated with preexisting nevi; of these, 15 had congenital features with a CNAM largest diameter of 1.5 cm. These 15 cases were melanomas of the superficial type with a mean tumor thickness lower than that of ANAM (0.33 vs 1.50). There were no differences between the locations of CNAM and other melanomas. Male patients were significantly more affected. ELM microscopy permitted us to detect the early malignant changes in nevi and thus to improve our diagnosis. A high percentage of small congenital nevi were found to be associated with melanomas. They may be considered as melanomas precursors. Because of their large number and frequency, prophylactic removal of all SCN is not feasible. However, they should be removed as soon as possible when clinical or ELM changes are observed.

Management of Small and Intermediate Congenital Nevi: A Nationwide Survey in Italy

“…Similar results (7.9%) were published by Betti et al [23] in a study of 190 cases of melanoma. In addition, in a large study of 1,954 cases of primitive melanomas, an association with melanocytic nevi was found in more than half of cases (58%); of these, 38% had a histological pattern consistent with congenital nevus [24].…”

Congenital melanocytic nevi: Where are we now?

“…In a study of 190 patients with melanoma, 15 developed melanomas within small congenital nevi; the average age of melanoma development among these patients was 41.04 years, no cases developed before puberty, and all 15 melanomas were of the superficial spreading type. 100 Aggregated data from several studies have estimated that 19% to 21% of all melanomas are associated with small CMN. 101,102 However, most studies show an incidence rate of melanoma in small and medium CMN of\1%.…”

Precursors to melanoma and their mimics: nevi of special sites

“…Although these lesions are very common in the community, there is an association of these 'congenital pattern nevi' with melanoma, although this is insufficient to warrant wholesale eradication of these lesions with the aim of preventing melanoma. 63 Combined nevi, which in the most common form combine the 'congenital pattern' just described with focal changes of blue nevus, 64 also appear to be common on the skin of the face. 65 In a recent study, 101 junctional and compound nevi from the ear were studied.…”