Acquired reactive perforating collagenosis with IgA nephropathy.

A 25-year-old Japanese man developed numerous discrete umbilicated papules on his face, trunk, and both forearms at the onset of IgA nephropathy. The newest lesion was a nonumbilicated skin-colored papule. On histopathologic examination, alteration of capillaries was observed in both newer and umbilicated papules. In our case, a primary cause of the reactive perforating collagenosis could be an alteration of the capillaries.