Sweat gland disturbances in granuloma annulare and necrobiosis lipoidica.

We studied sweat gland distribution, density and activity in thirteen cases of granuloma annulare and ten cases of necrobiosis lipoidica, using a combination of the plastic impression and starch-iodine methods. The pattern of sweat gland disturbance in the two diseases was entirely different. In necrobiosis lipoidica an intense and uniform hypohidrosis was detected throughout the lesion, whereas in granuloma annulare the disturbance followed the morphology of the lesion (the papular border showed complete anhidrosis, whereas the flat central part of the lesion showed only moderate hypohidrosis or normal sweating). The method assigns numerical values to the 'relative density' and the 'relative activity' of the functioning sweat glands compared with normal skin, thus permitting statistical evaluation of the results.