RESUMO
Objective To summarize the clinical characteristics of patients with occupational melanosis. Methods Diagnostic data of 69 patients with occupational melanosis was analyzed using retrospective analysis. Results The main occupational hazards for the 69 patients with occupational melanosis were coal tar, petroleum and its fractionated products, pigments and dyes and their intermediates, rubber additives and rubber products. The median length of occupational exposure and disease latency were 8.0 and 6.0 years, respectively, with a highly positive correlation between them (Spearman correlation coefficients=0.962, P<0.01). Skin lesions were mainly found on exposed areas such as the face-to-neck and limbs, prevalence of 94.2% and 75.4% respectively. And 78.3% of patients had skin lesion on more than two sites. The lesions were mostly in the form of irregular flakes (59.4%), with a gray-black color (44.9%). About 43.5% of patients experienced skin itching. Complete blood count, liver function, and kidney function were all within normal ranges. Skin biopsy results showed that epidermal hyperkeratosis, thinning of the spinous layer, liquefaction degeneration of basal cells, increased superficial dermal melanocytes, and infiltration of lymphocytes, histiocytes, and melanocytes around the blood vessels. Reflectance confocal microscopy (RCM) detection showed focal liquefaction degeneration of basal cells in the lesions, with a significant infiltration of melanocytes and inflammatory cells in the dermal papillae and superficial layers. Conclusion The primary target organ of occupational melanocytes is the skin, and no damage to other organs was identified thus far. Results from skin biopsies and RCM examinations can be used for differential diagnosis.