Labial salivary gland biopsy for diagnosing immunoglobulin light chain amyloidosis: a retrospective analysis

Our goal was to evaluate the usefulness of labial salivary gland (LSG) biopsy for diagnosing immunoglobulin light chain (AL) amyloidosis, by comparing bone marrow and skin biopsies in the same patient population. This retrospective study included 34 consecutive patients who showed evidence of monoclonal proteins and symptoms considered to be due to amyloidosis, and who underwent a tissue biopsy from LSG between January 2005 and December 2012 at Nagoya City University Hospital. All samples of superficial tissues, including LSG, bone marrow, and skin, were independently evaluated as having amyloid deposits by a central review, which was blind to clinical information. An AL amyloidosis diagnosis was based on evidence of amyloid deposition in any biopsied tissue. Eighteen patients were diagnosed with AL amyloidosis. The sensitivity for detecting amyloid deposition was highest in biopsies of LSG at 89 %, followed by 77 % for bone marrow, and 72 % for skin. Amyloid deposition was detected in at least one superficial tissue of all the 18 patients. An LSG biopsy may be appropriate as a first-choice procedure to diagnose AL amyloidosis. Multiple biopsies of superficial tissues, including LSG, bone marrow, and skin, are recommended to increase the sensitivity for diagnosing AL amyloidosis.