Nodular amiodarone lung disease.

The antiarrhythmic drug amiodarone accumulates in many organs of the body. Amiodarone lung disease (ALD) most commonly manifests clinically as an interstitial pneumonitis. The few reports of nodular ALD generally have been in the clinical and radiographic literature. No detailed histopathologic analysis of nodular ALD is available. We report 4 patients with nodular ALD, all of whom had excision of a nodule and none had a preoperative diagnosis of ALD. The radiographic suspicion before excisional biopsy in all 4 cases was malignancy. The initial pathologic suspicion in all 4 cases was either an abscess or vasculitis. In 3 of the 4 cases, where the dosages were known, each patient received 800 mg/d for 7 or more months. All cases have strikingly similar histopathology, with vacuolated histiocytes massed within alveoli to form macroscopic nodules with tissue breakdown. Ultrastructural examination of lung and peripheral nerve in 1 case showed the characteristic inclusions of amiodarone in the cytoplasm of swollen histiocytes. Vacuolated histiocytes filled with these inclusions indicate the effect of the drug, but in these 4 cases there was tissue destruction, which indicated disease. The necrotizing nature of the massed histiocytes in the absence of infection or obstruction suggests the correct etiologic diagnosis even when the history of administration of the drug is not available at initial review.