The role of minor salivary gland biopsy in the diagnosis of systemic amyloidosis: results of a prospective study in 62 patients

Histological demonstration of amyloid deposits is required for the diagnosis of amyloidosis. Less invasive approaches than the biopsy of the organs involved, such as abdominal fat and salivary gland biopsy are feasible. In AL amyloidosis, abdominal fat sensitivity is approximately 80%. We report the results of salivary gland biopsy in 62 consecutive patients with suspected systemic amyloidosis and negative abdominal fat aspirates. Amyloid deposits were detected in 7 of the 12 patients in whom amyloidosis was eventually diagnosed. The deposits were characterized as AL λ in 4 cases (57%), AL κ in 2 (29%), and AA in 1 (14%). In the remaining five patients, amyloidosis was diagnosed by organ biopsy and characterized as AL λ in three subjects and AL κ in two. Overall, the diagnostic sensitivity of the salivary gland biopsy in patients with negative fat aspirate was 58%, specificity 100% and negative predictive value 91%. A sequential diagnostic approach based on second-step salivary gland biopsy can spare organ biopsy to more than half the patients with systemic amyloidosis.