Localized Pulmonary Amyloidosis Associated With Sjögren's Syndrome, Coexisting Lymphoid Interstitial Pneumonia, and a Severe Double Aortic Lesion: A Case Report and Literature Review.

Amyloidosis is a protein-folding disease that results in the deposition of misfolded proteins into various tissues of the body, resulting in dysfunction of the affected organ. It is caused by a heterogeneous group of disorders caused by extracellular deposition of misfolded proteins as insoluble fibrils. Involvement of the lungs can present as nodular, tracheobronchial, or diffuse interstitial, and can be mistaken for cancer or infection on imaging. The combination of Sjögren's syndrome, chronic activation of B cells, and the risk of developing a lymphoproliferative disorder can lead to the rare deposition of amyloid. In cystic lung disease, the amyloid deposition can be misattributed to lymphoid interstitial pneumonia (LIP). An evaluation for progressive dyspnea and chest pain was done in a 68-year-old female patient diagnosed with Sjögren's syndrome and severe degenerative aortic valve disease (severe double aortic lesion). The patient's high-resolution computed tomography scan demonstrated diffuse pulmonary cysts of the thin-walled variety that are consistent with a pattern of LIP, with several solid nodules layered on top of each other exhibiting increased attenuation, as well as some that are calcified on the mediastinal windows. An October 2023 core lung biopsy revealed structures resembling bony spicules with dystrophic calcification and an adjacent amorphous area that lacked cells; malignancy was absent. Microbiological studies were negative for bacteria, fungi, and mycobacteria, and there were no malignant cells in the cytology. The patient's autoimmune testing revealed rheumatoid factor at 20.2 IU/mL, as well as anti-Ro (SSA) 125 and anti-La (SSB) 79.9. Sjögren's syndrome was confirmed by a salivary gland biopsy. Re-reviewing archived biopsy material in 2025 showed that the unexplained nodules still had atypical radiographic characteristics, with the Belizean red stain showing polarized light birefringence, confirming the presence of pulmonary amyloid. The functional assessment showed a 6-minute walk distance of 392 m with an oxygen saturation nadir of 85% at minute 4. Right heart catheterization with fluid challenge (August 2025) showed a mean pulmonary artery pressure of 24 mmHg, pulmonary artery wedge pressure rising from 12 to 18 mmHg, hypothesized cardiac output of 5.1 L/min, cardiac index 3.6 L/min/m², and pulmonary vascular resistance of 2.3 Wood units, consistent with mild pulmonary hypertension and a post-capillary contribution with severe aortic valve disease. The patient continues to be managed by a multidisciplinary team, with no systemic amyloidosis documented to date. When pulmonary nodules co-exist with Sjögren's syndrome, pulmonary amyloidosis, although rare, should be considered, especially when the syndrome co-exists with cystic changes that suggest LIP. Persistent atypical changes in radiology and biopsy should trigger a more thorough examination of stale biopsies. Secondary severe valve disease, augmenting pulmonary hypertension, should be an impetus for ongoing multidisciplinary care and a thorough ongoing assessment.