Diagnostic dilemma of tuberculosis in the foot and ankle.

BACKGROUND: Isolated involvement of bone in tuberculous infection is uncommon, and the variable clinical and radiological features may mimic pyogenic osteomyelitis, bone tumor or other inflammatory and neoplastic processes of the synovium. We have reported our experiences with the diagnosis of tuberculosis infection in the ankle and foot with the hope of providing sufficient information about these cases to lead to early diagnosis.

MATERIALS AND METHODS: We treated 15 patients with tuberculosis involving the foot and ankle between 1995 and 2005. They were followed for a minimum of 24 months, and the average duration of symptoms was 23 months. All patients underwent a physical examination, routine laboratory tests, plain radiographs, and a biopsy of the infection site. MRI studies were performed in 10 patients and a CT scan was done in one patient.

RESULTS: The lesions were located in the forefoot (2), midfoot (3) and ankle (10). From the imaging studies, the presumptive preoperative diagnoses were tuberculous osteomyelitis (7), pyogenic osteomyelitis (4), pigmented villonodular synovitis (2), amyloidosis (1), and avascular necrosis of the talus (1). These diagnoses were verified by granulomatous inflammation with or without caseous necrosis on histology and tubercle bacilli were cultured in four cases. In three cases the diagnosis was made by polymerase chain reaction (PCR).

CONCLUSION: When a patient presents with a localized, painful swelling and a persistent draining sinus of the foot and ankle, tuberculosis should be considered in the differential diagnosis. Additionally, we highly recommend taking a biopsy of the site of suspected infection because an early diagnosis is the key to successful treatment.