Several distinct linear patterns of skin lesions have been recognized for many years.1 These patterns include dermatomes2,3 (ie, herpes zoster), Langer lines4,5 (ie, pityriasis rosea), and the lines of Blaschko6 (ie, incontinentia pigmenti). Each of these patterns follows a distinctive linear expression that is most clearly visualized on the back. We report a new linear pattern observed in this location consisting of clinically and histologically proven seborrheic keratoses on the backs of elderly patients that follows what appears to be a linear, splayed, vertical distribution that we term a raindrop pattern.
Heffernan MP, Khavari PA. Raindrop Seborrheic Keratoses: A Distinctive Pattern on the Backs of Elderly Patients. Arch Dermatol. 1998;134(3):382-383. doi: