'Localized amyloidosis': 123I-labelled SAP component scintigraphy and labial salivary gland biopsy

In apparently localized amyloidosis, there is no appropriate test to determine whether systemic deposits exist. We studied the value of serum amyloid P component (SAP) scintigraphy and labial salivary gland (LSG) biopsy on patients with apparently localized amyloidosis in 12 patients who had neither clinical nor biological evidence of systemic amyloidosis. All patients had an LSG biopsy and echocardiography. Iodine-123-labelled serum amyloid P component (123I-SAP) scintigraphy was performed in all patients. Whole-body scintigraphy was done, and tissue retention was evaluated at 24 h and 48 h. Of these 12 patients, three had amyloidosis in their LSG and had abnormal 123I-SAP scintigraphy; these three had a secondary clinical history of systemic amyloidosis. Three other patients had abnormal 123I-SAP scintigraphy without detectable systemic amyloid deposits, but one had a previous history of bilateral carpal tunnel syndrome treated with infiltration. 123I-SAP scintigraphy in association with LSG biopsy may be helpful in determining the localized or systemic character of amyloid disease.