Sarcoid Pleural Effusion Presenting With Pachypleuritis: A Rare Manifestation in a Young Adult

Sarcoidosis is a systemic granulomatous disease of unknown etiology that predominantly involves the lungs and mediastinal lymph nodes. Although other organs may be affected, sarcoid-associated pleural effusion (SAPE) is relatively rare and often poses a diagnostic challenge. We report a case of a 24-year-old male who presented with pleural effusion (PE) and fever. Thoracentesis revealed an exudative PE with lymphocytosis. Microbiological studies were negative. He was empirically treated with amoxicillin/clavulanic acid and azithromycin for community-acquired pneumonia. Chest computed tomography showed nodular pleural thickening and a persistent small-volume PE. The patient underwent pleural decortication, and excisional biopsy of a lingular lymph node confirmed sarcoidosis. One year later, he developed functional impairment, and positron emission tomography-computed tomography revealed several hypermetabolic lesions, prompting corticosteroid therapy with a good response. At two years, lung function had normalized, residual pleural thickening remained stable, and treatment was withdrawn. Despite its low incidence, SAPE should be considered in the differential diagnosis of pleural effusion, particularly in young patients without comorbidities and with a high pleural fluid lymphocyte count. Exclusion of tuberculosis is fundamental for an accurate diagnosis, and in cases of active pleural disease, systemic treatment is essential to prevent pachypleuritis.