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Interferon-induced sarcoidosis is well documented. We report two new cases of sarcoidosis in two patients with hepatitis C virus infection treated with interferon alfa and ribavirin. These patients developed cutaneous sarcoidosis about 3 months after the beginning of the combination therapy. Spontaneous regression of the lesions was noted after discontinuation of the treatment. There have been more than 20 observations of the appearance or aggravation of this granulomatosis with interferon alfa and more recently with the combination of interferon alfa plus ribavirin. Dermatological signs are found in 50% of cases, and are often diagnostic. Other clinical symptoms of sarcoidosis resemble side-effects of interferon. The evolution is fairly stereotypical and is marked by a regression of the lesions following a dose reduction or curtailment of interferon. Interferon alfa acts by stimulating the T-helper (Th) 1 immune response. In addition to its antiviral action, ribavirin also enhances the Th1 response. Indeed, the superiority of the combination of interferon alfa and ribavirin in terms of antiviral action is corroborated by the enhancement of a Th1-type immune reaction by this combination. At the same time, this immune cell reaction triggers a greater granulomatous reaction.

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We report a patient with a sodium valproate-induced cutaneous pseudolymphoma, presenting with an erythematous papule, histologically mimicking a non-epidermotropic T-cell lymphoma. Polymerase chain reaction study of the skin biopsy revealed monoclonal rearrangement of the T-cell receptor gamma gene. Withdrawal of sodium valproate was followed by regression of the lesion, but 5 months after substitution by carbamazepine, two further papules appeared, with similar histological features and a T-cell clone identical to the initial one. Carbamazepine was stopped and the lesions disappeared without relapse over a 4-year follow-up. Sodium valproate is very rarely responsible for a hypersensitivity syndrome, and our case is the first report of sodium valproate-induced cutaneous pseudolymphoma. The recurrence with carbamazepine may be due to a common effect on T-cell lymphocyte function. The return of the same monoclonal population shows that the recurrence of monoclonal T cells may be observed in benign conditions and is not an exclusive hallmark of cutaneous lymphoma.