New clinical and ultrastructural findings in hydroxychloroquine-induced cardiomyopathy--a report of 2 cases.

Hydroxychloroquine- or chloroquine -induced cardiomyopathy is a rare but potentially fatal condition. Hydroxychloroquine and chloroquine are often used for long-term treatment of rheumatic diseases and for malaria prophylaxis. Hydroxychloroquine- and chloroquine-induced cardiomyopathy have well-described microscopic features, with the classic electron microscopic findings of myelin figures (myeloid bodies). We report on 2 new cases with novel findings. The first case, in a patient with systemic lupus erythematosus, was found to have megamitochondria in addition to myelin figures seen by electron microscopy. The second report describes the first case of hydroxychloroquine cardiomyopathy described in a patient with scleroderma. These novel findings will add to the present knowledge of hydroxychloroquine-induced cardiomyopathy in its pathology and its implication for treatment of rheumatic diseases.