Widespread and Long-Enduring Hyperkeratosis Lenticularis Perstans (Flegel's Disease): Clinico-Pathological and Dermoscopic Features of a Rare Presentation

Hyperkeratosis lenticularis perstans, also known as Flegel's disease (FD), is a rare cutaneous disorder affecting mainly the lower extremities of middle-aged people. Due to its rarity, this disease is usually not recognized by physicians resulting in a delay in diagnosis, especially in those cases with atypical cutaneous involvement. Herein, we present a 72-year-old woman who developed FD characterized by a generalized distribution, involving, in addition to the lower limbs, the trunk and the upper limbs as well. We performed a description of the dermoscopic and pathologic features of this rare entity, also carrying out a brief reappraisal of the cases of FD with a diffuse, atypical and generalized distribution that have been described in the literature. Histopathology with clinical correlation is the cornerstone of the diagnosis, even and especially in atypical cases. This patient with a disease duration of 58 years also represents the longest-lasting case of FD reported in the literature.