These results show a low yield of positive photopatch tests. Thus, despite the large increase in the use of UV filters over the last decade, the development of PA reactions remains rare. Furthermore, most of the common UV filter photoallergens identified in this study, including PABA, amyl dimethyl PABA and benzophenone-10, are now rarely used in sunscreen manufacture, while isopropyl dibenzoylmethane was voluntarily removed from the market in 1993. Currently, benzophenone-3 is the commonest contact photoallergen still in widespread use. In contrast, the UVB filter octyl methoxycinnamate, used in a number of sunscreens, produced only two positive PA reactions in 12 years of testing. Nevertheless, although these reactions are extremely rare, patients with photodermatoses such as PLE and chronic actinic dermatitis do represent a group of patients at increased risk of developing photoallergy. Further photopatch test series should be regularly reviewed and updated, as the relevance of individual photoallergens changes over time. Currently, there is no evidence that PA reactions represent a common clinical problem.

Livedoid vasculitis, otherwise known as segmental hyalinizing vasculitis or livedo reticularis with summer ulceration, is a chronic disease with lesions affecting the feet and lower legs. Early lesions show petechiae, but characteristic features are recurrent, bizarrely shaped ulcers that heal to leave hyperpigmentation and atrophie blanche. The aetiology of the disorder is unknown, but the histology shows fibrin deposition within both the wall and lumen of affected vessels. The absence of a sufficient perivascular infiltrate or leucocytoclasia argues against a vasculitis, being more in keeping with a thrombo-occlusive process. Four patients with livedoid vasculitis with ulceration are described, all of whom had associated raised anticardiolipin antibodies but no other evidence of systemic disease. We suggest that livedoid vasculitis may be a manifestation of the antiphospholipid syndrome and recommend that all patients are screened for this. We also discuss treatment options for this often resistant condition.

Clinicians are, by profession, capable assessors of severity of disease. Whether from severity they can deduce a patient's Quality of Life (QoL) is debatable. This study compared scores for physician-assessed severity with the corresponding scores for patient QoL, as assessed using Dermatology Life Quality Index (DLQI) questionnaires in 57 dermatological out-patients. Although there was some degree of correlation between the two measures (r = 0.56), interpretation of QoL from disease severity is clinically unreliable. Thus a physician's assessment of QoL requires formal assessment using a tool such as the DLQI.

Although pellagra is a recognized complication of isoniazid therapy, the diagnosis may be overlooked or delayed--sometimes with life-threatening consequences. We report a case of isoniazid-induced pellagra which occurred despite pyridoxine supplementation. Drug withdrawal and supplementation with niacin led to a rapid and sustained clinical improvement. The possible mechanisms of isoniazid induced pellagra are discussed.

Treatment of acne improves QoL, particularly in those with more depressive symptoms at the outset. Mood deterioration was not detected, but the possibility of subtle or rare mood effects of isotretinoin cannot be ruled out.