Pulmonary amyloidosis in Sjögren's syndrome: a case report

Primary Sjögren's syndrome (pSS) is a chronic inflammatory autoimmune disease characterized by lymphocyte proliferation and progressive exocrine gland damage, which can involve multiple organs, including the lungs. However, secondary pulmonary amyloidosis is rare. This study summarizes the clinical features of this condition through the diagnosis and treatment of a 44-year-old female patient and a literature review. The patient was admitted due to "bilateral pulmonary nodules discovered over 4 years ago." Chest CT revealed scattered multiple nodules and mass shadows in both lungs, some with calcification. Blood tests indicated leukopenia and thrombocytopenia. Immunological tests showed positive anti-nuclear antibodies and anti-SS-A antibodies. Combined with symptoms of dry mouth and dry eyes, as well as tear film breakup time and salivary secretion function tests, the patient was diagnosed with primary Sjögren's syndrome. Percutaneous lung biopsy pathology revealed amyloidosis with granulomatous reactions, and Congo red staining was positive, confirming the diagnosis of primary Sjögren's syndrome complicated by pulmonary amyloidosis. The patient was treated with hydroxychloroquine and remained stable upon discharge, with follow-up ongoing for 6 months. A literature search (May 2014 to May 2024) identified 15 relevant articles (3 in Chinese, 12 in English). The results showed that all reported patients were female, with a median age of 66 years. Only 46.7% presented with symptoms of dry mouth and dry eyes at initial diagnosis, 14 cases had immunological abnormalities, and 1 case had cytopenia. Chest imaging revealed that 53.3% of patients had pulmonary nodules with cystic changes, and 26.7% had calcifications. Pulmonary amyloidosis, as a rare complication of pSS, is prone to misdiagnosis and missed diagnosis, and its treatment and prognosis lack evidence-based medical support. pSS often has an insidious onset, with some patients presenting initially with extraglandular organ damage rather than exocrine gland involvement. Pulmonary involvement may manifest as multiple nodules with calcifications and/or cystic changes or interstitial lung disease on imaging. When patients present with these imaging features that cannot be explained by common diseases, pSS should be considered. Lung biopsy is crucial for diagnosis and exclusion of confounding diseases such as lymphoma. Recognizing the pulmonary imaging characteristics of pSS can help reduce missed diagnoses, enable early diagnosis, and guide appropriate treatment.