Abstract
The patient is a 77-year-old man with black nodular lesions on his right temple. He had been aware of the lesions for some time. A part of the nodule had broken off; the patient was worried if it might be skin cancer and visited us. Dermoscopy of the black nodule showed a pseudonetwork in some area, but the major part of the lesion is occupied with a uniform structureless which covers the hair follicles completely below the nodules, blue-gray globules were scattered in a pinkish-white backgrand. These findings indicate the regression structure and are frequently observed in the regressing part of invasive malignant melanoma. Although regressing melanoma was suspected clinically, the pathological specimen revealed a regressing seborrheic keratosis. So the active treatment was not perfomed. When the patient visited us four years later, the lesion had disappeared completely. Reported cases of regressing seborrheic keratosis are very few in number and not well known. In such cases, clinical diagnosis and differentiation from malignant melanoma could be difficult even after dermoscopical observation, histopathological examination is therefore mandatory.
