Navicular tuberculosis: A rare localization of bone tuberculosis

Tuberculosis (TB) is a global public health problem endemic to Morocco. While extrapulmonary TB uncommonly presents in osteoarticular anatomic locations, tarsal or metatarsal osteitis can occur when TB presents in the tarsal bones. Clinical symptoms are often insidious causing a delay in diagnosis that may lead to bone destruction. While diagnosis can be guided by X-ray imaging, bacteriologic and histologic examination of the tissue allows for pathogen isolation, identification of the bacillus and strain sensitivity to antibacillary treatment. We report a rare case of navicular osteitis associated with tarso-metatarsal arthritis caused by tuberculosis in a 68-year-old man. This case illustrates an exceptional location of osteoarticular TB and support diagnostic difficulties encountered: (i) imaging is not specific; (ii) lesions are paucibacillary which reduces conventional microbiological methods sensitivity and (iii) the peripheral location of the Koch bacillus within the lesion dictates surgical biopsy than percutaneous puncture. We recommend testing for tuberculosis in any case of chronic osteolysis and/or arthritis of the foot, especially in TB endemic countries.