Drug-induced lupus (DIL) can comprise up to 10% of new lupus cases annually, and the list of medications associated with DIL is increasing. However, it can be difficult to recognize the connection between symptoms and a medication-induced autoimmune syndrome, which can lead to an invasive, costly workup. Given that the prognosis is usually good if therapy with the offending agent is stopped, it is important to identify this clinical entity promptly.
A healthy, 44-year-old man with hypertension was seen initially because of shoulder pain and again after development of fevers and chest pain. He underwent a thorough infectious workup and then oncologic workup, with his clinical course complicated by a Histoplasma infection. After evaluation by subspecialists, the patient was thought to have an autoimmune condition related to DIL. His symptoms improved after he discontinued the offending drug therapy and received a course of corticosteroids.
Our case highlights how DIL should be on the differential when seemingly disparate symptoms develop in a patient receiving DIL-associated medications. Lupus is one of the “great imitators,” in which symptoms can be ascribed to many different underlying causes. Although this patient’s presentation may have been confounded by concomitant histoplasmosis, his improvement with cessation of hydralazine treatment argues in favor of DIL. His continued atypical serologic test results could be residual from his DIL and should normalize with time. However, it raises the question whether this bout of DIL has unmasked a previously quiescent autoimmune condition, requiring continued observation.