[Tenosynovitis confirmed by MRI during anti-tuberculous treatment suspected due to isoniazid--2 case reports and literature review].

The adverse effects of anti-tuberculosis agents is an important problem for treatment of tuberculosis. We report 2 possible cases of isoniazid-induced tenosynovitis. Case 1: A 49-year-old man with untreated diabetic mellitus presented with hypesthesia and difficulty grasping with his right hand 1 month after starting treatment of tuberculosis of the lung and pleuritis using isoniazid, rifampicin, ethambutol, and pyrazinamide. His symptoms were due to tenosynovitis, which was detected by magnetic resonance imaging. The clinical course and isoniazid challenge test revealed that the condition was related to isoniazid. After discontinuing isoniazid treatment, his symptoms gradually improved. Case 2: An 78-year-old man operated on for rectal cancer 3 weeks previously presented with edema and arthralgia of both hands 1 month after starting anti-tuberculosis treatment. His tuberculosis was diagnosed at preoperative screening tests for rectal cancer. Owing to a medical history of gout, pyrazinamide was discontinued. However, his symptoms did not improve. Magnetic resonance imaging revealed findings indicative of tenosynovitis. At the end of anti-tuberculosis treatment, his symptoms improved slightly within 6 months. Isoniazid-induced tenosynovitis and arthritis are rare adverse effects. However, they may be underestimated because the severity is variable. We suggest further investigations of the side effects of isoniazid using imaging techniques such as magnetic resonance imaging.