Tuberculous tenosynovitis of flexor digitorum longus tendon

Extrapulmonary tuberculous involvement of musculoskeletal system accounts for approximately 1% to 5% of cases. Tuberculous involvement of the feet tendon is even rarer. We are reporting an extremely rare case of tuberculous tenosynovitis of flexor digitorum longus tendon in a 68-year-old man. A 68-year-old farmer from India presented with a painless swelling over medial aspect of left ankle for 3 months. Examination of left ankle and foot revealed non-tender, fluctuant swelling, anteroinferior to medial malleolus. Plain radiographs of the ankle and foot revealed no abnormality. Laboratory findings, including erythrocyte sedimentation rate, were within normal limits. When excision was attempted, purulent material came out on incising the subcutaneous tissue. Gram staining, acid fast bacilli staining and pyogenic culture detected no organism. Histopathological examination of the granulation tissue showed non-specific inflammation. The wound healed well with secondary intention over a 15-day period. Two months postoperatively, swelling recurred at the same site. Magnetic resonance imaging showed small hypointense collection in the tendon sheath of left flexor digitorum longus behind the left ankle joint and adjacent lower end of tibia on the T2-weighted, STIR, and gradient (T2 with fat saturation) images, which appeared hypointense on T1-weighted images, suggestive of tenosynovitis. Tenosynovectomy was performed. Mycobacterium tuberculosis was isolated on culture. Histopathological examination, this time revealed epitheloid granuloma. Patient recovered uneventfully after 5-drug antituberculous regime.