We have compared the therapeutic effectiveness of a new UVB fluorescent sunlamp, the Philips TL-01 lamp, which emits a narrow peak around 311-312 nm, with the currently used Philips TL-12 lamp, in 10 patients with psoriasis. We also compared the tumour inducing capacity of the two lamps in hairless mice. The therapeutic effect of the TL-01 lamp was superior to that of the TL-12 lamp in nine of the 10 patients. In the mice, the median tumour induction time was significantly longer in animals exposed to the TL-01 lamp. Phototherapy with the new type of lamp requires a higher dose than phototherapy with the usual broadband UVB sources. In practice this means that more lamps are needed in the light cabinet. However, the new lamps appear to provide more effective and safer phototherapy for psoriasis.

To investigate the light sensitivity to various wavelength regions in lupus erythematosus (LE), phototests were performed in 24 LE patients with clinical photosensitivity (7 had systemic LE, 9 discoid LE, and 8 subacute cutaneous LE). Skin areas (measuring 40-60 cm2) were irradiated daily, maximally six times. With all three light sources used (emitting UVB, UVA, and visible light respectively) abnormal papular or papulosquamous reactions could be induced. In four of the 20 patients reacting abnormally, lesions occurred 10 or more days after cessation of the phototests; this indicates that the problem of photosensitivity in LE may be greater than appreciated so far.

We have studied the iron metabolism in nine patients with erythropoietic protoporphyria (EPP) and three patients with sideroblastic anaemia (SA). All, except one EPP patient were iron deficient. The SA patients had a secondary haemochromatosis. The bone marrow aspirates of patients with SA and also three patients with EPP had a high incidence of ring sideroblasts. Ultrastructural examination of the bone marrow consistently showed finely dispersed electron-dense deposits localized in mitochondria of erythroblasts in all patients with EPP and SA. Mitochondrial electron energy-loss spectroscopy (EELS) indicated identical iron compounds in erythroblasts of all EPP and SA patients. These findings indicate that the mitochondrial iron utilization is disturbed in EPP and SA. The observation of mitochondrial iron deposition in erythroblasts in EPP and SA suggests that this failure is not of pathognomonic value for diagnosis of SA, but is apparently the result of an inefficient haem synthesis, in EPP due to a defective ferrochelatase. The mitochondrial iron deposition does not depend on the iron status (iron overload or iron deficiency) of the EPP patient.

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Two patients suffering from therapy-resistant Darier's disease were treated with topical 5-fluorouracil (5-FU). The drug was applied in a concentration of 1% in a cream base, once daily, in left-right comparison with either 7.5% salicylic acid in petrolatum or 0.05% vitamin A acid cream. Both patients were on long-term treatment with oral retinoids. After 1 week of treatment, a considerable improvement was already apparent on the 5-FU-treated side, in comparison with the salicylic acid- and vitamin A acid-treated sides. Subsequent treatment of all skin lesions with 5-FU for a further 2 weeks resulted in complete clearance of the lesions. Remission periods were of 2-6 months duration. There were no significant adverse effects of treatment. Haematological parameters remained unchanged during the therapy. Topical 5-FU is a safe and useful addition to currently available treatments for Darier's disease.