Ultrasound-Guided Synovial Biopsy in Undifferentiated Monoarthritis: A Case Series From Bangladesh.

Ultrasound-guided synovial biopsy (USG-SB) is a minimally invasive technique useful in diagnosing joint tuberculosis, particularly when conventional methods fail. However, its role in diagnosing tubercular arthritis in Bangladesh remains underexplored. This study presents a case series of five patients with monoarthritis - three with ankle involvement and two with knee joint tuberculosis - evaluated using USG-SB or aspiration. The procedures were performed using a high-resolution musculoskeletal ultrasound (14-6 MHz probe, Mindray, Shenzhen, China). Synovial tissue samples were analyzed via histopathology and GeneXpert (Cepheid, Sunnyvale, California, US) testing, while synovial fluid was examined via cytology, acid-fast bacilli (AFB) staining, and GeneXpert. Tuberculosis was confirmed histologically in three cases, GeneXpert was positive in two, and AFB staining was positive in one. These findings support USG-SB as a safe, effective, and minimally invasive diagnostic option for tubercular arthritis, particularly in resource-limited settings like Bangladesh.