Precursors to melanoma and their mimics: nevi of special sites

Abstract

Melanocytic nevi, which are benign tumors of melanocytes, may have occasional cosmetic significance but, for the most part, they are important only in relation to melanoma. Nevi are the most important simulants of melanoma, both clinically and histologically, and can usually be reliably distinguished from melanomas using published criteria. Some lesions are characterized by greater degrees of atypia and may be more difficult to diagnose. Dysplastic nevi are among the most important simulants of melanoma. Nevi may also be important as potential precursors of melanoma; however, most nevi are stable and will not progress to malignancy. Nevi are vastly more common than melanomas and the rate of progression of individual lesions is very low. Therefore, nevi are not as a rule managed by wholesale excision to prevent melanoma. Nevi are also important as risk markers, identifying individuals at greater risk of developing melanoma in the future. Dysplastic nevi and, to a lesser extent, common acquired and congenital nevi are among the most important melanoma risk markers. Nevi of special sites have been identified as nevi that may show atypical features suggestive of a dysplastic nevus or of a melanoma. However, they are not risk markers and they are not malignancies. Nevi of genital skin, acral skin, and flexural skin are among the most important 'nevi of special sites'. It is important, in considering the differential diagnosis of a lesion in a special site, to avoid overcalling such a lesion as a melanoma or a dysplastic nevus because this could lead to excessive treatment. Conversely, it is important to avoid undercalling a lesion that is a dysplastic nevus or a melanoma as a nevus of special sites, because in this circumstance a patient could lose the opportunity either for surveillance to recognize a developing melanoma at an early, curable stage, or for definitive treatment of an established malignancy. In this monograph, dysplastic nevi and nevi of special sites are compared and contrasted in relation to melanoma.

A clinico-pathological study of pigmented cutaneous lesions: a one-year prospective study in a tertiary care hospital

“…In the present study, among females the most common lesion was benign melanocytic nevi 17 (54.8%) which was similar to observations of Schafer et al 7 Nevi are benign melanocytic tumours that have cosmetic significance and may act as stimulants or precursors to melanoma. 8 In male's nevus sebaceous was most common lesion 5 (38.5%) which was similar to Rubegni et al, Rajesh et al 1,9 Majority of these lesions were situated on the face 29 (65.9%) and were similar to Rajesh et al In present study, it was observed that malignant melanoma was seen in 2 cases and both were females, which was comparable to other studies. 1,10 but dissimilar to the observations of KORA survey.melanoma is an aggressive tumour, its incidence in India is uncommon when compared to the West.…”

Morphologic analysis of periumbilical nevi

“…It is known for many years that a group of nevi in different anatomic sites that may simulate both dysplastic nevi and melanoma [1,6,7,12]. these nevi have been termed generically "nevi of special sites".…”

“…Nicolau Antonela-Anca 2 , Așchie Mariana 1,2 AbStrAct A large number of publications recognize that there are melanocytic lesions with microscopic features similar to melanoma, related to their location, with no prognostic importance. those locations are represented by the ear, the milk lines (axillary, breast, periumbilical and inguinal regions), palms, soles and flexural regions.…”

“…those sites include the head and neck (specially the ear), the "milk line" (axillary, breast, periumbilical and inguinal), acral regions (palms and soles) and flexural regions. The microscopic aspect of these nevi necessitates sometimes differentiation from melanoma [1,2]. the milk lines are the progenitors of mammary glands and nipples.…”

“…[6] The role of the estrogen in the biologic behavior and the histologic aspect is still unsure, because there were no major differences between males and females. Starting from this study we have analyzed the periumbilical nevi (as part of the milk line) in order to obtain a histopathologic and immunohistochemical model [1,4,5,6].…”