Background: The authors' purpose was to evaluate the histopathology of flexor tenosynovium in true, idiopathic recurrent carpal tunnel syndrome for the presence of abnormal inflammatory or pathologic findings that might explain causation or that differ from those previously described for primary, idiopathic carpal tunnel syndrome.
Methods: Thirty-five patients (19 women and 16 men; mean age, 72 years) underwent open revision carpal tunnel release a mean 13 years (range, 0.5 to 30 years) after primary carpal tunnel release. Recurrence was confirmed by recurrent symptoms, positive provocative tests, and electrodiagnostic testing. All patients underwent tenosynovial biopsy, including Congo red staining for amyloid.
Results: Histopathologic findings demonstrated noninflammatory, fibrous connective tissue in 31 of 35 patients (89 percent); and mild, chronic inflammation (without granulomas) in four of 35 patients (11 percent). Nine of 35 patients (26 percent) had positive results for amyloid, with a statistically higher incidence in men (p = 0.03) and advanced age (p = 0.02). Subtyping performed in eight of nine amyloid-positive specimens confirmed seven cases of transthyretin-type amyloid typically seen in localized (senile) amyloidosis and one case of light-chain amyloid in a patient who was subsequently diagnosed with myeloma.
Conclusions: Flexor tenosynovium in patients with recurrent carpal tunnel syndrome does not appear to be substantially different histologically from that previously described in primary idiopathic carpal tunnel syndrome, although a slightly higher prevalence of amyloid was seen in this group (especially older men). No patients have developed systemic amyloidosis. Routine biopsy of tenosynovium in idiopathic, recurrent carpal tunnel syndrome is unnecessary.