Responses To Thermal Stresses in Psoriasis of Hand

Fifteen subjects having psoriasis on the hand, comprising both sexes, between 22 and 56 years in age and suffering for durations varying from 10 months to 20 years each with a sex and age niatched control were studied. A thermistor thermometer measured the skin temperature in ambient condition at the finger tip and at selected sites on the dorsa of hands and fingers, both at lesion site and lesion-free adjacent ones. In all cases except one, the thermistor readings were significantly lower (p ) in the psoriatic lesions than in the uninvolved adjacent skin. The hands were next subjected to thermal stresses: first by immersion in an ice-water bath at O'C (cold challenge) and later in a hot water bath at 450C (heat challenge) each for a period of 60 seconds. Immediately after each stress period,ithe fingertip temperatures were recorded, in psoriatic subjects, the finger-tip temperature dropped on cold challenge and the amount of drop expressed as percentage of the basal temperature was significantly less (p ) than the corresponding value for the control. There was no significant difference (p 0.05) in the respo se to the heat challenge between psoriat c and normal subjects. It appears that there is some fault in the local vasomotor tone in subjects with hand psoriasis.