Bone scan in systemic amyloidosis

Thirty patients diagnosed as having systemic amyloidosis (six with primary amyloidosis and 24 with secondary amyloidosis) were given bone scans with 99Tcm-methylene diphosphonate in order to evaluate the skeletal and extra-osseous uptake and their clinical-scintigraphic correlation. Extra-osseous uptake appeared in nine instances, more frequently in primary (5/6) than in secondary (4/24) amyloidosis. Fourteen patients had clinical and echocardiographic suspicion of cardiac amyloidosis but only one showed cardiac uptake. Six patients had probable hepatic involvement but in only two cases was hepatic uptake seen. The extra-osseous uptake suggests the presence of amyloid deposits in the organs and soft tissues which take up the bone tracer. The absence of any uptake does not rule out amyloid infiltration.