[Reticular lentigo]

Abstract

We studied the clinical and histopathologic features in five patients with reticulated lentigo. This peculiar pigmented skin lesions has previously been described under the designations "acquired reticulated lentigo", ink spot lentigo, "reticulated melanotic macule" or "reticulated lentigo". Each of the 4 males and 1 females in our study (age range: 16 to 57 years; mean age: 34 years) had a single, 4-6 mm large, black macule with irregular, fingerlike extensions at the periphery. All lesions were situated on the upper back and surrounded by numerous sun-induced freckles. Dermatoscopic examination revealed irregularly formed "meshes" and confirmed the reticulated pattern seen clinically. Reticulated lentigo presented mostly in individuals with skin type 1, red to blond hair, and blue eyes. The clinical diagnosis in 4 out of 5 cases was melanoma in situ. Histopathologically, reticulated lentigo was mainly characterized by a sharply circumscribed hyperpigmentation of the lower epidermis with accentuation at the tips of elongated and clubbed rete ridges. In addition, a normal or slightly increased melanocyte number in the basal layer and an infiltrate of melanophages in the upper dermis was noted. Reticulated lentigo shows histopathologic features similar to those of melanotic macules on volar skin and mucous membranes. Because of its characteristic clinical, dermatoscopic and histopathologic features reticulated lentigo can be regarded as a distinctive clinicopathologic entity.