Response of chronic psoriatic plaques to localized heating induced by ultrasound.

Since tumor regression occurs after hyperthermia, this modality was applied to lesions of psoriasis. A relatively uniform temperature and heat distribution within a lesion was induced using an ultrasound transducer operating at 5.265 MHz. Twenty-two chronic psoriatic plaques in nine patients were heated to temperatures ranging from 42 to 45 degrees C for 30-minute periods three time weekly for a total of four to ten treatments. Fifteen lesions (68%) cleared completely within the heated zone, five lesions (23%) responded partially, and two lesions (9%) remained unchanged. Biopsy specimens taken before and during treatment showed reformation of the granular layer as the earliest and most consistent change in responsive lesions. Remissions were temporary, and the lesions usually relapsed within three months. Hyperthermia may be a useful therapeutic and investigative tool for the problem of psoriasis.