Lungs under siege: exploring a rare case of diffuse alveolar-septal pulmonary amyloidosis—a case report

Background: Diffuse alveolar septal involvement in pulmonary amyloidosis is an exceptionally uncommon manifestation, frequently detected post-mortem due to its elusive antemortem diagnosis. Case Description: We present the case of a 72-year-old woman with a history of systemic amyloidosis, notable for the absence of pulmonary symptoms before she presented with a persistent, productive cough and worsening dyspnea. Echocardiography indicated a reduced heart function and diastolic dysfunction. Right heart catheterization revealed elevated pulmonary pressures, hinting at pulmonary hypertension, with a biopsy confirming primary or light chain (AL) amyloidosis. High-resolution chest computed tomography (CT) and bronchoscopy identified diffuse bronchiectasis, nodules, and amyloid deposits in lung tissues, with no evidence of giant cells but positive for light chain lambda amyloidosis. Despite negative Congo red staining, positive amyloid P and thioflavin T stains, along with electron microscopy, supported the amyloidosis diagnosis. Bone marrow analysis and serum light chain assays further confirmed a lambda light chain type multiple myeloma. After participating in a clinical trial with bortezomib and dexamethasone treatment, the patient saw significant respiratory improvement, consistent with her diagnosis but showing no progression to advanced myeloma. Conclusions: This report highlights a rare case of diffuse alveolar septal amyloidosis, an exceedingly unusual pattern of involvement associated with a particularly dismal prognosis. Our objective is to contribute to the broader understanding of this disease, emphasizing the challenges in making an antemortem diagnosis and underscoring the importance of recognizing diverse pulmonary manifestations of systemic amyloidosis for timely intervention and management.