Israel Medical Association Journal

Cardiac amyloidosis is a form of restrictive cardiomyopathy resulting from the accumulation of misfolded protein aggregates in the myocardial extracellular space. Cardiac amyloidosis stems primarily from the misfolding of monoclonal immunoglobulin light chains (AL) originating from abnormal clonal plasma cell proliferation or transthyretin amyloidosis (ATTR).

Diagnosis of amyloidosis demands a high index of suspicion and requires histological confirmation of pathognomonic green birefringence under polarized light when an infiltrated tissue specimen is stained with Congo-red staining [1,2].

Pleural involvement of systemic amyloidosis has rarely been reported and is considered a serious complication [3]. Pleural amyloidosis is diagnosed with the identification of amyloid deposits in pleural biopsy specimens. However, pleural biopsies are rarely performed for this indication.

We describe the case of a patient with AL cardiac amyloidosis presenting as intractable pleural effusion and diagnosed via pleural biopsy.

Background: Cardiac amyloidosis (CA) is characterized by the extracellular deposition of misfolded protein in the heart. Precise identification of the amyloid type is often challenging, but critical, since the treatment and prognosis depend on the disease form and the type of deposited amyloid. Coexistence of clinical conditions such as old age, monoclonal gammopathy, chronic inflammation, or peripheral neuropathy in a patient with cardiomyopathy creates a differential diagnosis between the major types of CA: amyloidosis light chains (AL), amyloidosis transthyretin (ATTR) and amyloidosis A (AA).

Objectives: To demonstrate the utility of the Western blotting (WB)-based amyloid typing method in patients diagnosed with cardiac amyloidosis where the type of amyloid was not obvious based on the clinical context.

Methods: Congo red positive endomyocardial biopsy specimens were studied in patients where the type of amyloid was uncertain. Amyloid proteins were extracted and identified by WB. Mass spectrometry (MS) of the electrophoretically resolved protein-in-gel bands was used for confirmation of WB data.

Results: WB analysis allowed differentiation between AL, AA, and ATTR in cardiac biopsies based on specific immunoreactivity of the electrophoretically separated proteins and their characteristic molecular weight. The obtained results were confirmed by MS.

Conclusions: WB-based amyloid typing method is cheaper and more readily available than the complex and expensive gold standard techniques such as MS analysis or immunoelectron microscopy. Notably, it is more sensitive and specific than the commonly used immunohistochemical techniques and may provide an accessible diagnostic service to patients with amyloidosis in Israel.

Background: Amyloidosis of familial Mediterranean fever (FMF) may lead to end-stage renal failure, culminating in kidney transplantation. Since amyloidosis is prompted by high serum amyloid A (SAA) levels, increased SAA is expected to persist after transplantation. However, no data are available to confirm such an assumption.

 Objectives: To determine SAA levels in kidney-transplanted FMF-amyloidosis patients and evaluate risk factors for the expected high SAA levels in this patient group.

Methods: SAA, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values were obtained from 16 kidney-transplanted FMF-amyloidosis patients, 18 FMF patients without amyloidosis and 20 kidney-transplanted patients with non-inflammatory underlying disease. Demographic, clinical and genetic risk factors evaluation was based on data extracted from files, interviews and examination of the patients.

Results: SAA level in FMF patients who underwent kidney transplantation due to amyloidosis was elevated with a mean of 21.1 ± 11.8 mg/L (normal ≤ 10 mg/L). It was comparable to that of transplanted patients with non-inflammatory disorders, but tended to be higher than in FMF patients without amyloidosis (7.38 ± 6.36, P = 0.08). Possible risk factors for the elevated SAA levels in kidney transplant patients that were excluded were ethnic origin, MEFV mutations, gender, age and disease duration.

Conclusions: Kidney-transplanted patients with FMF-amyloidosis and with other non-FMF causes displayed mildly elevated SAA levels, possibly resulting from exposure to foreign tissue rather than from various FMF-related factors.