Treatment of psoriasis with trioxsalen baths and dysprosium lamps.

Photochemotherapeutic treatment of psoriasis with trioxsalen baths (0.5 mg/1) for 15 minutes followed by irradiation with dysprosium lamps (Osram HQI-TS) healed or nearly healed the psoriatic lesions in 18 patients within 3-5 weeks. A control area treated with the Ingram method showed a slower healing in 9 of these patients. Methoxsalen bath was not as effective in healing at the concentration used (1 mg/l). The bath method is easy to administer and cosmetically acceptable. Sensitisation to light is maximal immediately after the bath and disappears more quickly than after painting with an alcoholic trioxsalen solution. By using baths, there is less risk of accidental burns or uneven pigmentation than with the often time-consuming local application of psoralen solutions. Toxic systemic effects, which are possible with oral treatment, are less apt to occur. The dysprosium lamps give high intensity in the UV-A region. Exposure times of 10 seconds to 8 minutes are effective in the treatment of psoriasis, where both the UV-B region itself and the UV-A in combination with trioxsalen have psoriasis-healing properties.