A case of carpal tunnel syndrome caused by giant gouty tophi: the usefulness of DECT for the diagnosis, preoperative planning and postoperative evaluation of atypical cases

We report a rare case of carpal tunnel syndrome with flexion contracture of the fingers caused by giant gouty tophi requiring surgery. A 57-year-old man presented with a 2-year history of numbness in both hands with gradual limitation of his right index and middle finger extension. The patient's right index and middle fingers exhibited flexion contracture and no passive extension while numbness in the median nerve area was also observed. A subcutaneous mass of approximately 2 cm was palpated on the palmar aspect of the patient's wrist, and Tinel's sign was positive throughout the median nerve region of the same area. Blood examinations revealed abnormally high uric acid levels and slightly elevated inflammatory markers. Various imaging tests confirmed a mass within the carpal tunnel and flexor tendon, suggestive of gouty tophi, with median nerve compression. Moreover, the results of electrophysiological testing indicated median neuropathy. Thus, carpal tunnel syndrome with flexion contracture of the fingers caused by giant gouty tophi was diagnosed; hence, surgery was performed. Follow-up at 6 months postoperatively revealed improvement in the flexure contraction of the index and middle fingers and also activities of daily living; however, sensory disturbance of the median nerve region still persisted. Postoperative dual-energy computed tomography (DECT) revealed an almost complete surgical removal of the gouty tophi observed preoperatively within the carpal tunnel and flexor tendon. DECT not only helps with the diagnosis of and surgical planning for atypical tophi but also is extremely useful for postoperative evaluation to determine whether the lesion was removed.