The liver in systemic amyloidosis: insights from 123I serum amyloid P component scintigraphy in 484 patients

Abstract

Background and aims: The liver is frequently involved in amyloidosis but the significance of hepatic amyloid has not been systematically studied. We have previously developed scintigraphy with 123I serum amyloid P component (123I-SAP) to identify and monitor amyloid deposits quantitatively in vivo and we report here our findings in hepatic amyloidosis.

Methods: Between 1988 and 1995, 805 patients with clinically suspected or biopsy proven systemic amyloidosis were evaluated. One hundred and thirty eight patients had AA amyloidosis, 180 had AL amyloidosis, 99 had hereditary amyloid syndromes, and 67 had dialysis related (beta 2 microglobulin) amyloid. One hundred and ninety two patients with amyloidosis were followed for six months to eight years.

Results: Hepatic amyloid was found in 98/180 (54%) AL and 25/138 (18%) AA patients but in only 1/53 patients with familial transthyretin amyloid polyneuropathy and in none with dialysis related amyloidosis. There was complete concordance between hepatic SAP scintigraphy and the presence or absence of parenchymal amyloid deposits on liver histology. Amyloidosis was never confined to the liver. Mortality was rarely due to hepatic failure, although hepatic involvement with AA amyloid carried a poor prognosis. Successful therapy to reduce the supply of amyloid fibril protein precursors was followed by substantial regression of all types of amyloid.

Conclusions: SAP scintigraphy is a specific and sensitive method for detecting and monitoring hepatic amyloid. Liver involvement is always associated with major amyloid in other organ systems and carries a poor prognosis in AA type. Appropriate therapy may substantially improve prognosis in many patients.

Figure 1

Serum alkaline phosphatase in 691 patients who underwent liver scintigraphy with ¹²³I-SAP showing poor predictive value of elevated serum alkaline phosphatase for liver amyloidosis.

Figure 2

Serial posterior abdominal ¹²³I-SAP scans of a patient with AA amyloidosis complicating rheumatoid arthritis. The scan at presentation (A) shows uptake of the tracer into amyloid deposits in the spleen, kidneys, and adrenal glands. The patient did not respond to anti-inflammatory treatment and the follow up scan two years later (B) shows additional localisation of tracer into the liver; reduction of the renal signal is due to end stage renal failure.

Figure 3

Kaplan-Meier estimate of survival in patients with systemic AA amyloidosis with and without hepatic involvement on ¹²³I-SAP scintigraphy.

Figure 4

Serial anterior whole body ¹²³I-SAP scans in a patient with AL amyloidosis who presented with hepatomegaly and liver dysfunction. The initial scan (A) shows massive uptake of tracer into amyloid deposits in the liver, spleen, and bone marrow. The follow up scan six months later (B), following intensive chemotherapy, shows much less uptake of labelled SAP into the liver and bone marrow indicating substantial regression of the amyloid in these organs. Liver function had also returned to near normal levels.

Figure 5

Kaplan-Meier estimate of survival in patients with systemic AL amyloidosis with and without hepatic involvement on ¹²³I-SAP scintigraphy.