Pulmonary sarcoidosis induced by interferon-α therapy

Recombinant interferon-alpha (IFN-alpha) is being increasingly used in the treatment of chronic hepatitis C. It has been recently recognized that IFN-alpha can induce the development of sarcoidosis, presumably through its ability to stimulate the T(H)1 immune response. IFN-associated sarcoidosis is histologically similar to de novo sarcoidosis and is characterized by tightly compact epithelioid nonnecrotizing granulomas. IFN-induced sarcoidosis may be unsuspected clinically, as the most common side effects of IFN-alpha simulate the symptoms of sarcoidosis. It is therefore important for pathologists to be aware of this association and encourage clinicians to carefully review the medication history in cases of pulmonary nonnecrotizing granulomatous inflammation where there is a history of hepatitis C, as discontinuation of IFN-alpha, can ameliorate the symptoms of sarcoidosis.