The Histogenesis of malignant melanoma in relation to pre‐existing pigmented lesions

Abstract

One hundred and twenty-nine cases of malignant melanoma seen at Bangour General Hospital over an eleven year period were reviewed clinically and histologically. In 51 patients (39.5%) there was a history of pre-existing pigmented lesion at the site of the melanoma. In 14 cases (10.8%) histology confirmed traces of a benign melanocytic naevus. The relationships between naevus cells and malignant melanocytes are described. The patterns most frequently observed were those of intradermal naevus cells in the deeper part of an invasive melanoma and of a compound naevus undergoing malignant change in its junctional component. From these histological observations a histogenetic sequence of events is postulated. In the 37 patients with a positive history of a preceding pigmented lesion but no histological traces of a naevus, the percentage incidence of Lentigo Maligna (LM) and Superficial Spreading Melanoma (SSM), as compared with the 78 patients with a negative clinical history, was significantly higher than the incidence of nodular melanoma (NM). Although LM and SSM are thought to have separate histogenesis and aetiology, they share an important clinical and histological factor, i.e. in both, the radial growth phase is preceded by a, more or less, prolonged stage of intraepidermal horizontal growth. It is postulated that this pre-existing lesion of atypical melanocytic proliferation rather than a hypothetical benign naevus is in most cases the precursor of an invasive melanoma.

Recognition of early melanoma: a monocentric dermoscopy follow‐up study comparing de novo melanoma with nevus‐associated melanoma

“…8 Even more considered as unjustified and not cost-effective is the use of SDDI to detect nevus-associated melanomas at earlier stages, considering that the general rate of transformation of benign melanocytic lesions and even dysplastic nevi is extremely low. 7,[10][11][12][13][14][15][16] Yet, for many reasons, this frequency may have been overestimated or underestimated mainly because depending on the stage of development of the tumor, malignant cells may overgrow the preexisting benign melanocytic cells. 7,[10][11][12][13][14][15][16] Yet, for many reasons, this frequency may have been overestimated or underestimated mainly because depending on the stage of development of the tumor, malignant cells may overgrow the preexisting benign melanocytic cells.…”

Use of OralN-Acetylcysteine for Protection of Melanocytic Nevi against UV-Induced Oxidative Stress: Towards a Novel Paradigm for Melanoma Chemoprevention

“…If successfully implemented, this strategy would have a presumed benefit , since a reduction in pro-oncogenic oxidative stress in nevi over the course of many UV exposures would be predicted to decrease long-term (lifetime) melanoma risk. In addition, there would be less oxidative damage over time in isolated melanocytes, from which the majority of melanomas arise (2). …”

“…Although melanoma may arise directly from isolated melanocytes, a significant fraction of melanomas develop from nevi (or moles) (2), which represent congenital or acquired clonal neoplasms of melanocytes (3). Nevi are far less prevalent on sun-protected skin and their development is related to sun exposure (4), which also is the major environmental risk factor for melanoma (5).…”

The dysplastic nevus: From historical perspective to management in the modern era

“…Based on the literature, it appears that 20–30% of melanomas appear to arise from nevi. 111–113 Two studies similarly found that approximately 20% of melanomas had an histologically-associated DN, 114, 115 while another found DN remnants in association with only 7% (34/512) of melanoma cases. 116 …”