Eccrine Function in Psoriasis Inversus.

Seven patients with psoriatic lesions of axilla and internatal cleft were tested by thermal and intradermal methacholine stimulation using the quinizarin test for sweating to determine the source of moisture causing maceration and absence of scaling in psoriasis inversus.Histopathological changes were non-specific: slight and patchy hyperkeratosis and parakeratosis, slight elongation of rete ridges and thinning of suprapapillary plates, microspongiosis and vesiculation in variably acanthotic prickle cell layer; dilated capillary loops less prominent than in typical psoriasis.Lesions clinically and histopathologically consistent with psoriasis inversus were anhidrotic. Maceration was due to spread of sweat from adjacent uninvolved skin, spongiosis and vesiculation, serum exudation and insensible perspiration.