Progressive Respiratory Failure in an Autopsy Case of Amyotrophic Lateral Sclerosis With Cardiac and Pulmonary Amyloidosis

A 76‐year‐old woman died of progressive respiratory failure 10 months after amyotrophic lateral sclerosis (ALS) onset. At autopsy, a neuropathological diagnosis of ALS was made. Only mild neurogenic changes appeared in the diaphragm. Transthyretin amyloid deposits were observed in the heart and lungs and diffusely located in the alveolar parenchyma, indicating diffuse alveolar‐septal pulmonary amyloidosis, which could impair gas exchange. Pulmonary amyloidosis may contribute to respiratory failure, potentially acting synergistically with respiratory muscle paralysis due to ALS and cardiac failure caused by cardiac amyloidosis.