Clinical and pathological features of renal amyloidosis: An analysis of 32 patients in a single Chinese centre

Aim:  To summarize the clinical and pathological features of renal amyloidosis in order to achieve early diagnosis.

Methods:  The clinical and pathological data of 32 patients with renal amyloidosis, diagnosed by renal biopsy in one renal centre, were retrospectively analyzed. Immunohistochemistry of amyloid A protein and immunoglobulin light chains was further performed on the renal specimens for further classification.

Results:  Twenty-four out of the 32 patients (75%) were not considered to have renal amyloidosis by local physicians; 91.7% (22/24) of them had at least one of the following signs: bodyweight loss, organ enlargement and decreased blood pressure. Twenty-nine out of the 32 patients (90.6%) were over 40 years, 30 patients (93.8%) had nephrotic syndrome, and 21 patients (65.6%) were found to have monoclonal light chain in serum or urine by immunofixation. Six patients (18.8%) were negative by Congo red stain and were diagnosed as having early renal amyloidosis by electron microscopy. Twenty-eight patients were diagnosed as having AL amyloidosis, two were suspected of having AL amyloidosis, one had AA amyloidosis and the status of the remaining patient was undetermined.

Conclusion:  Renal amyloidosis is frequently neglected by local physicians in China. Middle-aged nephrotic patients with weight loss, organ enlargement and monoclonal light chains in serum or urine should be highly suspected of the disease. Renal biopsies, especially electron microscopy, play a crucial role in the early diagnosis of renal amyloidosis.