Lymphocytic interstitial pneumonia and pseudolymphomatous lymphadenopathy as the first manifestation of primary Sjögren syndrome

We report the case of a man in his 30s who presented with exertional dyspnoea and dry cough for 18 months, along with fever and generalised lymphadenopathy (cervical and axillary) for 3 months. He had no feature indicating a connective tissue disorder. High-resolution CT of the chest revealed bilateral and diffuse thin-walled cysts with multiple mediastinal lymph nodes, consistent with a cystic interstitial lung disease. His pulmonary function test showed a severe restrictive disease and an autoimmune workup revealed strong positivity for anti-SSA/Ro52. Minor salivary gland biopsy showed lymphocytic foci with a focus score of >1. Based on the 2016 American College of Rheumatology–European Alliance of Associations for Rheumatology (ACR–EULAR) classification, the patients’ diagnosis of Primary Sjögren’s was confirmed. A transbronchial lung biopsy on histopathology showed diffuse polyclonal lymphoplasmacytic interstitial infiltration with germinal centre formation, consistent with lymphocytic interstitial pneumonia. In view of the extensive lymphadenopathy, lymphoma was systematically ruled out through lymph node excision, bone marrow examination and serum electrophoresis, all of which supported a benign reactive process. The patient was diagnosed with lymphocytic interstitial pneumonia and pseudolymphomatous lymphadenopathy as the initial manifestation of primary Sjögren’s syndrome and showed clinical stability following treatment with systemic corticosteroids and mycophenolate mofetil.