Ultrasound in the evaluation of an unusual periarticular soft tissue tuberculosis.

This case report describes a 19-year-old patient with a swelling of the interphalangeal joint of the left thumb. Conventional radiography revealed erosive changes and a periarticular osteopenia. A marked increase in bone turnover of the entire thumb and wrist region was confirmed scintigraphically. Repeated attempts at arthrocentesis were unsuccessful. By ultrasonography, using a linear 7.5-Mhz transducer, a hypoechoic area with an anechoic core was located within the soft tissue swelling dorsal of the diaphysis of the proximal phalanx of the thumb. An aspiration of this anechoic area was possible and cytological analysis revealed an exudate with about equal percentages of lymphocytic/monocytic and polymorphonuclear cells and the microscopic and cultural detection of Mycobacterium tuberculosis. Ultrasonography is less expensive than MRI and may offer an important adjunct to evaluation of soft tissue problems.