Abstract
Ink spot lentigo, a rare variant of solar lentigo, is a small, monomorphous, solitary, black macule occurring on exposed areas. We report the case of a 51-year-old Japanese man with skin type III and ink spot lentigo. He noticed a 7-mm flat monomorphic black macule on his back 6 months prior. Dermoscopic examination revealed a dark brown-to-black typical pigment network. Histopathological analysis showed acanthosis and hyperpigmentation of the tips of the rete ridges with “skipped” areas lacking pigmentation. Melan-A Giemsa staining showed slightly increased numbers of melanocytes in the basal layer, without cytological atypia. There have been 20 cases of ink spot lentigo reported worldwide, which most presenting in individuals with skin types I–II. Although this is the first report of ink spot lentigo in Japan, other patients with this disease may have gone unreported as ink spot lentigo is not well known in Japan. The dark color of these lesions makes it difficult to distinguish them clinically from superficial spreading melanoma. Dermoscopy is extremely useful in revealing the monomorphous and homogeneous black typical pigment network of these lesions and allows differentiation from otherwise similar melanoma. We hope this case report will help in the wide recognition of ink spot lentigo in Japan in the future.
