Pulmonary calcified nodules and cysts as the initial presentation of Sjögren's syndrome secondary nodular pulmonary amyloidosis: a rare case report.

Background: Secondary pulmonary amyloidosis due to Sjögren's syndrome (SS) is an uncommon disease. However, pulmonary amyloidosis detected before the diagnosis of SS is exceedingly rare. Herein, we report a unique case of a 40-year-old female who presented with pulmonary calcified nodules and cysts as an initial manifestation of pulmonary amyloidosis. Further diagnostic evaluation revealed SS.

Case presentation: A 40-year-old non-smoking female presented with a cough, whose chest computed tomography (CT) scan revealed many lung cysts along with calcified nodules. Pathology revealed nodular pulmonary amyloidosis. Subsequent investigations excluded common related lymphoproliferative disorders and plasma cell dyscrasias. Combined with elevated levels of antinuclear antibody (1:640), positivity for the anti-Sjögren's syndrome A (SS-A)/Ro antibody, abnormal tear break-up time (BUT) and Schirmer test, the diagnosis of SS was established.

Conclusions: Pulmonary amyloidosis is a rare pulmonary manifestation of SS, especially with atypical early clinical symptoms, which can render diagnosis challenging. This case highlights that amyloidosis diagnosis precedes SS diagnosis. Moreover, it aims to alert clinicians that when multiple calcified nodules and cystic lesions are observed on chest CT, secondary pulmonary amyloidosis should be considered, and further investigations into related diseases such as SS should be conducted to avoid missed diagnoses.