In faired skinned population the incidence of melanoma is rapidly increasing. Beside environmental factors (UV-exposure) certainly other reasons for the observed “melanoma epidemic” have to be discussed. For diagnostic procedure classical histopathology is accompanied by immunohistochemistry and more recently molecular techniques. For therapy new modalities are available which—after many years of frustrating search for new drugs—are now able to prolong both disease/ progression free and overall survival.
Melanoma is the most important tumor in dermatooncology. Its incidence is around 10-fold lower than that of epithelial skin cancer but because of its capacity to metastasize early and the prevalence in younger patients melanoma has an important disease burden. The incidence of melanoma has been reported to increase rapidly in the last decades in countries with fair-skinned population. Incidence data reveal that in 1935 the lifetime risk to develop melanoma was 1: 1,500, in 1987–1:120 and today the risk is around 1:55. This indicates an increase that is faster than in any other form of cancer and raises the question of a melanoma epidemic . The increase of melanoma incidence per year is estimated in several studies to vary between 2 and 7 %, which means that the incidence doubles around every 10 years [2, 3]. As pathogenetic factors for the development of melanoma genetic predisposition, endogenous and environmental factors are well-documented , the worldwide increase of melanoma incidence in fair-skinned individuals is ascribed to changes in sun bathing attitudes during the last decades . Intermittent sun exposure, namely sunburns, during childhood has been specifically found to represent an important risk factor for melanoma development . Nevertheless, a lot of uncertainty concerning the role of UV-light in the development of melanoma still remains .
However, because the mortality rate of melanoma patients is quite stable and even in some subgroups decreasing is has been a matter of debate if this melanoma epidemic is a really existing phenomenon [1, 7]. Several arguments are provided to explain this dramatic increase in the incidence of melanoma :
Even though melanoma is not a type of cancer which clearly develops more often at older age, the rise in life expectancy leads to an increased lifelong risk. Especially melanoma on sun-damaged skin with an incidence peak in older ages is a slow-growing tumor, which is most often thin at the time of detection. Therefore, detection of this early manifestation of melanoma accounts for incidence rise but not for mortality. This age-related increase in melanoma incidence is a phenomenon which can be observed in all human diseases and has nothing to do with an “epidemic”. Public campaigns, more intensive surveillance and screening programs are indirectly resulting in incidence of cancer increase through higher detection rates. This reveals the effectiveness of these procedures . Higher incidence rates lead to a better public awareness and vice versa. In a study comparing trends in melanoma mortality in regions with and without skin cancer screening, strong evidence has been revealed that screening results in a reduction of melanoma mortality. However, it has been argued that in case of stable incidence rates, screening procedures only lead to a temporary rise . Climate changes also may contribute to a higher exposure to natural UV-irradiation .
Histopathologic investigation and diagnosis are the gold standard in the diagnostic procedures in pigmented tumors. Systematic changes in the interpretation of histopathologic features in pigmented tumors may lead to variation in the frequency of certain diagnosis, e.g., increases of melanoma diagnoses (see below).
The medico-legal climate is thought to be able to influence the diagnostic procedure both in dermatologists and in dermatopathologists. It has been discussed that the “diagnostic anxiety” to miss the diagnosis of melanoma may lead to an overdiagnosis of melanoma .
Very recent epidemiologic data from countries with a high risk of melanoma development show a tendency for a relative decrease of melanoma incidence in younger age groups. This phenomenon has been ascribed to the public campaigns, which resulted in an enhanced awareness about natural and artificial UV-radiation .
Diagnostic procedures in pigmented lesions
The dermatological examination of pigmented lesions should include a total body examination. Distribution and morphology comparison of the apparent pigmented lesions reveal important information (“Ugly duckling sign”, which means that the appearance of one of the lesions is different to all the others). For an initial evaluation of a single lesion patients and healthcare professionals use the A (asymmetry) B (border) C (color) D (diameter) E (elevation)-rule, which may be helpful, albeit not always reliable (especially in early melanoma).
Investigation of a suspicious pigmented lesion by epiluminescence microscopy should be a standard procedure in specialized centers and the dermatologic office. Both distribution of melanin pigment within the lesion as well as the vascular pattern within the tumor give important information about the dignity . Computerized techniques analyzing macroscopic and epiluminescence features are widely used and have been found to be safe and effective tools in the diagnostic procedure [11, 12]. However, these technologies do not substitute knowledge and skill of a well-trained dermatologist. In recent years, several new technologies have been developed which may be helpful as a non-invasive supplementary diagnostic procedure, e.g., confocal scanning microscopy or optical coherence tomography .
The gold standard in the diagnostic approach of melanoma is the histopathology. If the pathologist or dermatopathologist receives an adequate specimen, in almost all the cases a correct diagnosis will be achieved. To allow a reliable histological investigation, a completely excised tumor should be provided. In tumors removed by curettage, superficial shaving, or electrocautery correct diagnosing could be precluded by specimen selection. To differentiate nevus from melanoma a long list of morphologic criteria has been established . Most criteria focus on the architectural features of a given tumor, such as symmetry, borders, maturation, epidermal collerette, pigment distribution, inflammation, regression, etc. These morphological criteria almost always have to be microscopically checked by low magnification. Of course, consideration of cytologic features like pleomorphic nuclei and mitotic figures is also of great importance. Pathologists must be aware that a lot of lesions might be difficult to classify: nevi showing morphologic criteria of melanoma (mimicker of melanoma) and melanomas showing morphologic criteria usually observed in nevi (mimicker of nevus) . Several endogenous (hormonal, immunologic, site-specific) and exogenous factors (UV-light, scratching, rubbing) could influence the histopathologic appearance of a melanocytic lesion .
原文来自：Wien Med Wochenschr (2013) 163:354–358