Unilateral Extragenital Lichen Sclerosus Following Blaschko's Lines.

Lichen sclerosus is a chronic, immune-mediated dermatologic disorder primarily affecting the genital skin. Extragenital lichen sclerosus is rare, especially in men. We present a case of ELS in a 23-year-old male with lesions on the left upper extremity that had persisted for seven years. Over time, the lesions gradually spread to the left upper arm and scapular region. These lesions followed a band-like distribution along Blaschko's lines, without associated pruritus or pain. This unusual presentation posed a diagnostic challenge, highlighting the rarity of such manifestations.