We present a rare case of primary tuberculosis (TB) of the patella and patellar tendon, which initially mimicked gout on imaging. A 54-year-old male patient sought treatment for insidious anterior knee pain. Initial imaging, including ultrasound, revealed a soft tissue lesion involving the patellar tendon and eroding the inferior pole of the patella, with features resembling gout, a common arthropathy characterized by crystalline deposits in joints. The ultrasound appearance of the lesion led to the initial suspicion of gout, but further investigation was required. An ultrasound-guided biopsy confirmed the diagnosis of TB affecting the patella and patellar tendon.
Musculoskeletal TB, though less common than pulmonary TB, accounts for 10-19% of TB cases and is often seen in individuals with risk factors such as immunocompromised states. While TB can affect any joint, isolated involvement of the patella and patellar tendon is exceedingly rare. The imaging features of TB in this case were deceptive, mimicking the characteristic features of gout, which emphasizes the need for a thorough differential diagnosis, particularly in patients with risk factors for TB.
The patient was treated with antitubercular therapy, leading to a successful resolution of the infection. This case underscores the importance of considering TB in the differential diagnosis of musculoskeletal lesions, especially in areas where TB remains endemic. It also highlights the value of ultrasound in identifying soft tissue lesions, though care must be taken to avoid misinterpretation, particularly with rare infections such as TB. Clinicians should remain vigilant for uncommon presentations of TB and be aware of the potential pitfalls in imaging interpretation, ensuring an accurate diagnosis and appropriate treatment.
