Great imitator: an unusual presentation of osteoarticular tuberculosis of the knee with gram-negative bacterial arthritis.

A 33-year-old man presented with a 2-year history of right knee swelling with fungating masses and white-yellow discharge. Severe pain, limited movement and signs of sepsis were absent. Debridement, partial synovectomy and arthrotomy were done for the multiple sinuses that developed over the knee. Synovial tissue analysis yielded a positive acid-fast bacillus smear and Mycobacterium tuberculosis PCR test, while aerobic culture studies grew Pseudomonas aeruginosa and Acinetobacter baumannii Chronic granulomatous inflammation was seen on histopathology. Alongside antibiotic therapy, multiple debridements of the right knee were required to eradicate the infection and allow wound repair. A flap coverage with split-thickness skin graft was performed after the bacterial infection resolved, and the patient was discharged ambulatory with minimal pain. Such atypical presentations of monarthritis require immediate workup and a prompt referral to a multidisciplinary team to establish the diagnosis and initiate appropriate management before irreversible joint destruction and disability ensues.