We report three patients who developed unusually aggressive squamous cell carcinomas after receiving long-term azathioprine treatment for dermatological disorders. Two patients gave a history suggestive of moderate to excessive sun exposure, and the third suffered from chronic actinic dermatitis. Hence, ultraviolet light damage may have been a significant cofactor in the development of these malignancies. Careful follow-up is necessary in patients who are taking azathioprine long term, and who have previously been excessively exposed to ultraviolet light (UVL), or in whom future exposure is likely to be excessive. We suggest that strict sun avoidance measures are followed by patients on long-term azathioprine, or that alternatives to azathioprine therapy are considered, especially in individuals inherently at risk of UVL damage, and in those already showing clinical signs of such damage.

The incidence of positive patch test reactions to Quaternium 15 has increased by a factor of 3 within a relatively stable population over 2 years, while the incidence of reactions to Bronopol and Germall 115 has remained static. The problem of interpreting an apparent positive reaction to a formaldehyde-releasing preservative in a formaldehyde-sensitive patient is discussed.

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Mycobacterium kansasii, an atypical mycobacterium, is an uncommon cause of cutaneous and joint disease in immunocompetent patients. We report an unusual case of infection with this organism in a patient who initially presented with porphyria cutanea tarda (PCT), and who was noted also to have a crusted ulcer over the middle phalanx and swelling of the proximal interphalangeal joint of the right middle finger. The cutaneous ulcer healed with minocycline, but the joint disease required a combination of rifampicin and ethambutol before a therapeutic response was obtained.

No abstract