Investigations on light reactions in a patient with vitiligo are presented. The minimal erythema dose (MED) in the UVB area was approximately 1/3 of that in persons of skin type II. The application of furocoumarins (psoralens) increased light tolerance by 1 MED at 300-310 nm. Action spectrum studies with furocoumarins from Heracleum laciniatum showed the following order of potency: bergapten, pimpinellin, angelicin and sphondin. The efficacy was highest at 325-350 nm, with maxima at 330-335 nm. Pimpinellin was recently found to be phototoxic, but an action spectrum of sphondin is reported for the first time.

A case of chronic urticaria and vitiligo, associated with thyroiditis is described. Significantly elevated thyromicrosomal antibodies were found. Autoimmune reaction is a possible cause of the patient’s thyroid disease, vitiligo and chronic urticaria. Following PUVA treatment with a total dose of 300 J/cm² the patient’s urticaria subsided in all irradiated areas, only to relapse 2 weeks later. Subsequently courses of PUVA gave periods of remission. The treatment also induced repigmentation in the vitiliginous spots. The results indicate a local PUVA effect upon mediators or mediator-containing cells.

Experimental phytophotodermatitis was produced using homogenates from different parts of Heracleum laciniatum and long-wave ultraviolet light. The homogenates of leaves and flowers produced strong phototoxic reactions, fruit slightly less. Stems were either non-phototoxic or only slightly phototoxic. The roots of young plants did not evoke photosensitivity reactions, whereas the roots of older plants were strongly phototoxic; even roots collected from the frozen ground in December elicited strong reactions. Abdominal and midback skin were more photosensitive than skin of the lateral aspects of the underarms and legs.

The effect of combined UVB-UVA treatment in a group of 23 patients with severe atopic eczema was compared to UVB therapy alone in 33 patients. Mean age and number of treatments were approximately the same in the two groups. With UVB-UVA treatment, 48% achieved complete remission and in another 48% good improvements were obtained as compared to 27 and 58%, respectively, in the group treated with UVB alone. A few failures were recorded in the UVB group. Some possible explanations for the better effect of the combined UVB-UVA treatment are given.

A man suffering from actinic reticuloid for 2 years showed highly abnormal light sensitivity over a broad action spectrum. He has been successfully treated with daily whole-body topical applications of mechlorethamine, initially for 4 weeks and after a 2-month interruption, for 3 weeks. Gauzes moistened with the same solution were placed over lichenified areas for 10-15 min. His skin became normal pale and the lichenification decreased. After treatment his tolerance for daylight increased.