Blaschko-linear manifestations in polygenic inflammatory disorders

Abstract

This study delves into the intricate realm of Blaschko-linear dermatoses, initially described by Alfred Blaschko in 1901. The Blaschko lines forms V-shapes on the upper back, S-shapes on the abdomen, inverted U-shapes from the breast area to the upper arm, and perpendicular lines on the extremities. Blaschko’s lines are attributed to the widely accepted theory of embryonic mosaicism in epidermal cells.In this study, the Blaschko-linear manifestations of polygenic inflammatory disorders (BLMMPD) in Indian population is analyzed. Despite various studies on individual linear dermatoses, few Indian studies have explored the correlation between different Blaschko-linear dermatoses and their dermoscopic and histopathological features.The study, conducted from July 2023 to December 2023, includes 28 cases of Blaschko-linear dermatosis of diverse spectrum. Those with dermatosis along blood vessels, lymphatics, nerve trunk and following koebnerization were excluded. The demographic details, clinical manifestations and dermoscopic-histopathological characteristics were documented. In our case series, Lichen striatus and Linear Lichen planus (LP) were noted to be the most common among linear dermatosis, with a notable female predominance (Male: female ratio 0.75:1) and unilateral distribution (85.7%) on the extremities. Other conditions were linear psoriasis, verrucous epidermal nevus, epidermal nevus, hypomelanosis of Ito and Blaschko-linear acquired inflammatory skin eruption (BLAISE). The clinical-histopathological correlation manifested in 64.2% of cases, while dermoscopy exhibited an even higher correlation in 92.8% of cases. While the distribution pattern of linear dermatoses by itself serves as a valuable diagnostic clue, specific diagnosis can be achieved with more accuracy with the help of distinctive dermoscopic features and correlating them further with histopathological features.