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Results for “Skin Pigmentation”

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PubMed1999

Computer-assisted analysis of epiluminescence microscopy images of pigmented skin lesions.

BACKGROUND: Epiluminescence microscopy (ELM) is a noninvasive clinical tool recently developed for the diagnosis of pigmented skin lesions (PSLs), with the aim of improving melanoma screening strategies. However, the complexity of the ELM grading protocol means that considerable expertise is required for differential diagnosis. In this paper we propose a computer-based tool able to screen ELM images of PSLs in order to aid clinicians in the detection of lesion patterns useful for differential diagnosis. METHODS: The method proposed is based on the supervised classification of pixels of digitized ELM images, and leads to the construction of classes of pixels used for image segmentation. This process has two major phases, i.e., a learning phase, where several hundred pixels are used in order to train and validate a classification model, and an application step, which consists of a massive classification of billions of pixels (i.e., the full image) by means of the rules obtained in the first phase. RESULTS: Our results show that the proposed method is suitable for lesion-from-background extraction, for complete image segmentation into several typical diagnostic patterns, and for artifact rejection. Hence, our prototype has the potential to assist in distinguishing lesion patterns which are associated with diagnostic information such as diffuse pigmentation, dark globules (black dots and brown globules), and the gray-blue veil. CONCLUSIONS: The system proposed in this paper can be considered as a tool to assist in PSL diagnosis.

Computer Simulation↗

PubMed1995

[Dermatoscopy. An investigative method for the diagnosis of pigmented skin tumors].

Dermatoscopy is a non-invasive investigative technique which makes it possible to evaluate the pigmented structures of the epidermis, the dermo-epidermal junction and the papillary dermal layer. The melanin pigmentation of the epidermal basal cell layers, the so-called pigment network is the primary target of dermatoscopy. A number of diagnostic criteria and variables for the dermatoscopy of pigmented skin lesions have been developed. Cutaneous malignant melanoma is still increasing in incidence and mortality. An early diagnosis is decisive for the prognosis. Therefore, it is urgent to develop practical investigative methods which can increase the diagnostic sensitivity. Dermatoscopy is such a method, but it demands training and experience. Lack of suspicious findings by dermatoscopy does not exclude malignancy. A safe diagnosis can only be obtained by a histological examination.

Basal Cell Carcinoma↗

PubMed2006

Micro-melanoma detection: a clinical study on 206 consecutive cases of pigmented skin lesions with a diameter < or = 3 mm.

BACKGROUND: Very small pigmented lesions may represent an important diagnostic challenge to the clinician. OBJECTIVES: The aim of the present study was to establish the diagnostic value, in terms of sensitivity and specificity, of both clinical and dermoscopic examinations in a population of patients with unselected consecutive pigmented lesions with a maximum clinical diameter of 3 mm. PATIENTS AND METHODS: Two hundred and four consecutive patients bearing 206 pigmented skin lesions with a maximum diameter of 3 mm were seen and operated on. Twenty-three of these lesions were melanomas. Each lesion was subjected to both clinical and dermoscopic evaluation before surgery. The results were expressed in terms of sensitivity and specificity of both kinds of evaluation. RESULTS: Clinical evaluation produced a diagnostic sensitivity of 43% and a specificity of 91%. Dermoscopy resulted in a sensitivity of 83% and in a specificity of 69%. The comparison between the sensitivity values of the two diagnostic methods showed a significant difference (P < 0.01). A high value of significance was also obtained comparing the respective specificity values (P < 0.001). CONCLUSIONS: Detection of very small melanomas is feasible by accurate visual inspection. Dermoscopy appears to be an important aid to diagnosis, provided that physicians are aware of this type of lesion and maintain the index of suspicion at a high level.

Adolescent↗

PubMed2000

Apoptosis in skin pigment cells of the medaka, Oryzias latipes (Teleostei), during long-term chromatic adaptation: the role of sympathetic innervation.

Many teleost fish can adapt their body color to a background color by changing the morphology and density of their skin pigment cells. Melanophore density in fish skin decreases during long-term adaptation to a white background. Although cell death, especially apoptosis, is thought to be involved in these morphological changes, there are no data clearly supporting this mechanism. Using medaka fish, Oryzias latipes, we observed that, on a white background, melanophore size was reduced first and this was followed by a decrease in melanophore density caused by gradual cell death. The process of cell death included loss of cell activity, cell fragmentation, phagocytosis of the fragments, and clearance via the epidermis. Apoptosis was assessed by the appearance of phosphatidylserine on the cell surface of melanophores that had lost motile activity, and DNA fragments involved in cell fragmentation were detected by the TUNEL (TDT-mediated dUTP-biotin nick end-labeling) assay. However, when chemically denervated fish were used, although melanophore size was reduced as expected, cell death was suppressed even on a white background. In skin tissue culture, apoptosis in melanophores was stimulated significantly by norepinephrine, but not by melanin-concentrating hormone. These results indicate that melanophore density decreases by apoptosis, and suggest that sympathetic innervation has an important role in the regulation of apoptosis in melanophores. In analogous fashion, leucophores showed a significant decrease in density with an increase of cell death on a black background. We suggest that apoptosis regulates the balance of pigment cells in the skin of medaka fish to adapt their body color to a particular background.

Adaptation, Physiological↗

PubMed1992

Sex differences in skin pigmentation illustrated in art.

In different cultures of the world, many artists have made their female models lighter skinned than male models. There exists a biologic truth behind these observations. Several spectrophotometric studies have found that female skin reflectance is 2-3 percentage points above (that is, paler skin) that of males in diverse populations in Europe, Asia, Africa, and North and South America. The sex difference in skin pigmentation is, however, subtle and often difficult to appreciate. Probably artists have used pigmentation to emphasize sexual differences between men and women in the same way they use body size and musculature.

Female↗

PubMed2002

[Dermatoscopy: an asset in the clinical assessment of pigmented skin lesions].

Dermatoscopy is a non-invasive technique for the clinical diagnosis of pigmented skin lesions: a simple contact skin-surface microscope with a 10-fold magnification is used; the application of oil makes the horny layer translucent, as a result of which several additional criteria become available for the diagnosis of pigmented lesions. The evaluation is based on an algorithm involving asymmetry, border, colour and differential structure; another type of evaluation involves pattern analysis (global assessment, detailed assessment, assessment of the pigment network). The evaluation of these criteria requires formal training, after which the diagnostic skills of dermatologists have been found to increase; in non-dermatologists these skills decreased. Dermatoscopy has become an indispensible aid in clinical dermatology.

Algorithms↗

PubMed1992

In vivo spectrophotometric evaluation of neoplastic and non-neoplastic skin pigmented lesions. II: Discriminant analysis between nevus and melanoma.

Reflectance spectrophotometry from 420 to 780 nm on 31 primary melanoma and 31 benign nevi has been performed by using an external integrating sphere coupled to a spectrophotometer. Measurements show that reflectance spectra of melanoma and nevi manifest dissimilar patterns. From these spectra four variables, whose physical and/or physiological meanings remain to be investigated, have been derived. All of them are significantly different when compared between melanoma and nevi. A discriminant function between the two groups of lesions has been determined by using a stepwise discriminant analysis, resulting in a test with a sensitivity of 90.3% and a specificity of 77.4%. This method of discrimination between melanoma and nevi seems to have a discriminating power almost equal to that of a clinical judgement from a specialized medical doctor, thus suggesting a new method for screening skin pigmented lesions.

Diagnosis, Differential↗

PubMed1965