Spontaneous Shrinkage after Rapid Progression in Nodular Pulmonary Amyloidosis: A Case Report

Nodular pulmonary amyloidosis is a lung amyloid deposition disorder that often presents as single or multiple slow-growing nodules. Rapid progression and spontaneous regression of nodules are rare, and their longitudinal manifestations at computed tomography have not been well described. Herein, we report the case of a 78-year-old man with a solitary pulmonary nodule that increased in size from 16 mm to 21 mm over 6 weeks. The volume doubling time for the nodule was 37 days. Before referral, the patient underwent inconclusive bronchoscopy at another hospital. A diagnosis of nodular pulmonary amyloidosis was established after a second bronchoscopy with a biopsy using endobronchial ultrasonography with a guide sheath. The patient was diagnosed with interstitial lung disease and Sjögren's syndrome. Although the nodule increased, and multiple nodular lesions newly appeared 6 months later, these pulmonary involvements decreased or disappeared simultaneously without treatment. Herein, we describe the shortest volume doubling time for nodular pulmonary amyloidosis. Repeat bronchoscopies may contribute to the diagnosis of pulmonary amyloidosis.