Background and aim: Psoriasis is a chronic inflammatory dermatosis that affects 0.6% to 4.8% of the population. Phototherapy is commonly used in the treatment of this disease. According to the results of previous studies that showed difference in minimal erythema dose between different body sites, it seems that the responses of psoriatic lesions are also different in various body sites. Our objective was to compare the response of psoriatic lesions to phototherapy in various body sites.
Materials and methods: Forty patients with generalized chronic plaque-type psoriasis were enrolled in this study. All patients were examined prior and during phototherapy course every 10 sessions. In each patient time of clearance of psoriatic lesions at trunk, upper and lower extremities were recorded separately.
Results: At the end of phototherapy course the lesions of the trunk were cleared completely in 32 patients, and remained partially in 8 patients. The lesions of the upper limbs were cleared completely in 37 patients, and remained partially in 3 patients. The lesions of the lower limbs were cleared completely in 22 patients, and remained partially in 16 patients. Incomplete responses were significantly higher on the lower limbs than the trunk and upper limbs.
Conclusion: Therapeutic response of psoriatic lesions to phototherapy is lower on the lower limbs
than the trunk and upper limbs.