Bathtub suction-induced purpura.

We report two cases of bathtub suction-induced purpura. Two girls, ages 9 and 14 years, developed recurring purpura "spontaneously" in the same lower back location and in the same U-shaped distribution. The patients had similar histopathologic findings, with extravasated erythrocytes and a sparse superficial inflammatory infiltrate. After extensive evaluation, one patient eventually admitted to self-inducing her lesions by creating suction against a bathtub. The second patient denied self-inflicting her lesions; however, her purpura improved when she stopped taking baths.