Introduction Post-obstructive pneumonia (POP) is an infection of the lung parenchyma that arises distal to a bronchial obstruction, commonly associated with malignancies such as lung cancer. In these cases, the tumor obstructs the bronchus, impairing secretion clearance and creating a favorable environment for infection. In patients with multiple myeloma, the occurrence of AL amyloidosis, where amyloid light chains deposit in various organs, further complicates the clinical picture. In non-smoker patients with a history of multiple myeloma and new-onset POP, the presence of a bronchial mass should raise suspicion for amyloidoma and plasmacytoma.

Case A 58-year-old non-smoker female with a history of multiple myeloma, neuropathy, and chronic kidney disease presented with shortness of breath, fever, productive cough, hypotension, tachycardia, tachypnea and a dull, constant pain radiating from the right chest to the back. Initial chest X-ray revealed consolidation and a mass in the right middle lobe. After treatment for pneumonia, a follow-up chest CT identified a 4.6 cm x 5.4 cm mass with calcifications and septation, raising suspicion for malignancy due to bronchial obstruction. The mass was surgically resected, and histopathological analysis confirmed amyloidoma. Further workup was negative for systemic amyloidosis, and myeloma evaluation indicated the patient was in remission.

Discussion Tracheobronchial amyloidosis is the most common form of localized primary pulmonary amyloidosis, characterized by the deposition of amyloid light chain (AL) proteins within the bronchial structures. This condition can present with symptoms that closely resemble bronchogenic carcinoma, including cough, dyspnea, hemoptysis, and wheezing, largely due to airway obstruction and luminal stenosis. Bronchoscopic evaluation often reveals nodules, masses, or diffuse narrowing of the bronchial lumen, making biopsy critical for accurate diagnosis. Post-obstructive pneumonia, a common complication of bronchial obstruction, can lead to serious outcomes such as empyema, lung abscess, and fistula formation if not treated promptly. To mitigate these risks and improve airway patency, treatment typically involves bronchoscopic interventions, including laser resection, stenting, and external beam radiation, which help to alleviate symptoms and prevent further complications.