Natural history of cutaneous malignant melanoma

Abstract

The rising incidence of cutaneous malignant melanoma with the consequent increase in mortality from melanoma has intensified efforts to understand the factors that initiate the malignant transformation of melanocytes and to define those tumor-host interactions that play a relevant role in the clinical course of this disease. Increased exposure to solar radiation has been proposed as an explanation for the rising incidence of melanoma observed in light-skinned races. Because of the low incidence of melanoma in darkly pigmented races and its tendency in these individuals to develop in relatively nonpigmented areas, such as the sole of the foot, it is postulated that melanin, in addition to its wellknown photoprotective effects, may protect against certain intrinsic carcinogenic agents. Developing cutaneous malignant melanomas progress through several cell types that have varying potentials for invasion and metastasis. This developmental process can be appreciated by examination of the various histologic types of melanomas. Early superficial spreading melanoma and lentigo maligna melanoma are characterized by cells that exhibit a prolonged intraepidermal growth phase, and most of these lesions can be diagnosed while they are still curable by simple surgical therapy. Subpopulations of more aggressive cells eventually develop, however. These cells also may characterize the initial stages of nodular melanoma in which the intraepidermal growth phase is absent and early invasion is common. Prognosis for survival depends on the depth of invasion of the primary tumor. Microstaging of the depth of invasion together with information as to mitotic index, sex, site, age, and histologic type will usually predict the

Letters to the Editor

“…In his Table III, the proportions of body surface area at different sites appear to have been transposed, such that the surface area of the upper limb is given as almost twice that of the lower limb. The reference quoted (Boyd, 1935) was unavailable to us, but the distributions of body surface area given in other studies (Elwood & Lee, 1975;Briele & Das Gupta 1979) The corrected distribution of melanocytes shown above is quite similar to the site distribution of malignant melanomas in women, particularly as reported by Crombie from the North American Cancer Registries. That a relationship between risk of melanoma and numbers of melanocytes at different sites is more apparent in women than meni, may be explained by the comparative lack of body hair in women.…”

Transcriptomic Profiling of Sequential Tumors from Breast Cancer Patients Provides a Global View of Metastatic Expression Changes Following Endocrine Therapy

“…The relative divergence in gene expression reflected the histology of the original tumor and the disease latency period. Although disease progression in some cancers is rapid (22,23), in ER-positive breast cancer, metastasis may occur decades after resection of the primary tumor (24). The greatest degree of divergence in gene expression was observed in the ER-positive PGR-positive luminal A patient (patient 1) with a metastasis-free survival period of >10 years.…”

The Pedunculated Malignant Melanoma: A Misunderstood and Neglected Variant

“…It is exceedingly malignant and has a dismal prognosis. The degree of malignancy of pedunculated malignant melanomas is not known exactly, but their prognoses are probably less dire 4,5 …”