The sweat gland in cutaneous vasculitis.

Cutaneous vasculitis commonly presents as palpable purpura, and the late stages may become nodular, bullous, infarcted and ulcerated. Involvement of sweat glands in vasculitic lesions has not been previously described. In a detailed study of 48 cases of non-infarcted cutaneous vasculitis, 18 (36%) revealed morphologically abnormal sweat glands. Basal cell degeneration, necrosis, regeneration and basal cell hyperplasia were found in the excretory ducts. Necrosis of the secretory gland was seen either as apoptosis involving the clear cells or as a whole gland necrosis involving both cell types. This unusual feature has only been described in association with coma, commonly due to barbiturate and carbon monoxide poisoning. Its presence in non-infarcted vasculitis adds support to the hypoxia/ischaemia hypothesis. The functional impact of such lesions in widespread cutaneous vasculitides requires further study.