Early Histiocytic Pleuritis Revealing Tuberculosis on Repeat Thoracoscopy: A Case Report.

Tuberculosis (TB) continues to pose a global health challenge, particularly in its extrapulmonary forms such as pleural and pericardial involvement. These presentations often mimic other conditions and yield inconclusive results on initial microbiological and histopathological testing due to their paucibacillary nature. We report the case of a 45-year-old previously healthy man who presented with recurrent pleural and pericardial effusions. Extensive investigations during the first admission, including pleural fluid analysis, polymerase chain reaction (PCR), and thoracoscopic biopsy, were non-diagnostic. Histopathology initially revealed chronic histiocytic inflammation without necrosis, a finding frequently considered nonspecific but which may represent an early stage of tuberculous pleuritis. The patient improved transiently but presented two months later with contralateral pleural effusion. Repeat thoracoscopy demonstrated multiple "sago-like" nodules, and pleural biopsy confirmed granulomatous inflammation with acid-fast bacilli (AFB). Mycobacterium tuberculosis was subsequently cultured, confirming the diagnosis. Anti-TB therapy was initiated with rapid clinical and radiologic improvement. This case highlights that isolated histiocytic inflammation on pleural biopsy should raise suspicion for early tuberculous pleuritis, particularly in endemic regions or in patients with recurrent or unexplained serous effusions. Repeated or targeted thoracoscopic sampling remains crucial when initial results are inconclusive. Early recognition and timely initiation of therapy are essential to prevent complications and improve outcomes in pleuro-pericardial TB.