A 69-year-old man had been diagnosed with atrial fibrillation and cardiogenic cerebral infarction 1 month earlier and been prescribed anticoagulants. He did not show any consequences of the cerebral infarction. He was aware of his dyspnea on exertion and had a dry cough one week before admission. He had bilateral carpal tunnel syndrome for which surgery had been performed 10 years ago. No significant contributory family history was noted. He had a smoking history of 80 pack-years.
His vital signs were as follows: body temperature, 36.9C; blood pressure, 139/91 mmHg; heart rate (HR), 107/min; respiratory rate, 16/min, and oxygen saturation, 96% (room air). Inspiratory crackles were audible in the lungs bilaterally. His blood test results revealed leukocytes, 8,100/muL (neutrophils, 68.3%; lymphocytes, 20.4%; and eosinophils, 2.6%), C-reactive protein, 1.08 mg/dL; KL-6, 979 U/mL, and brain natriuretic peptide, 233 pg/mL. M protein, and Bence Jones protein were not detected by immunoelectrophoresis (Table).
Chest radiography revealed cardiomegaly and an infiltration shadow in the right lung field (Fig. 1A). Chest computed tomography (CT) revealed multiple infiltrative and ground-glass opacities in the lungs bilaterally (Fig. 1B). An electrocardiogram (Fig. 2A) revealed HR of 118/min, atrial fibrillation, low potentials on limb induction, and poor-R wave progression on V1-3 wave. Echocardiography (Fig. 2B, C) revealed a hypertrophic myocardium with high echogenicity. Bronchoscopy was performed to identify the cause of the clinical and infiltrative shadows. The TBLB specimen of the lower lobes of the right lung showed polypoidal organizing lesions protruding into the alveolar spaces (Fig. 3A); organizing pneumonia (OP) was diagnosed and treatment with steroids was initiated.
However, cardiac amyloidosis was also suspected owing to the presence of a hypertrophic myocardium with low potentials on electrocardiographic limb guidance and a medical history of bilateral carpal tunnel syndrome. A biopsy of the stomach, duodenum, and skin was performed; however, amyloid deposition was not observed. Therefore, Congo red stain was added to the TBLB specimens, which were stained positive (Fig. 3B, C), and polarized light microscopy revealed apple green birefringence amyloid deposits (Fig. 3D) and diffuse amyloid deposits in the alveolar septum (Fig. 3B). Technetium 99m pyrophosphate scintigraphy revealed the strong accumulation of technetium pyrophosphate in the inferior wall (Fig. 4); amyloid deposition of TTR was positive and mutations with amino acid changes were not observed in the TTR gene. Based on the above findings, ATTRwt amyloidosis was diagnosed by TBLB, so we planned to administer tafamidis.
Chest CT following treatment using steroids for OP revealed residual ground glass opacity under the pleura (Fig. 5), and pathology of the biopsied TBLB specimens revealed amyloid deposition in the alveolar septum; thus, we construed a diagnosis of diffuse alveolar-septal amyloidosis.