Clinicopathological Spectrum of Renal Amyloidosis in Young

Amyloidosis is a complex multi-system disorder characterized by deposition of an aberrant protein in tissues with kidney being the main target organ. The age of presentation of amyloid A (AA) amyloidosis is highest among adults aged 60-80 years followed by 45-55 years. However, presentation in younger age group is rare. We aimed to study the clinicopathological spectrum of patients with biopsy-proven renal AA amyloidosis aged <35 years in the last five years. This retrospective study was done on patients admitted from January 2015 to December 2019. Nine cases of AA amyloidosis diagnosed on kidney biopsy in ≤35 years of age were included in the study. Clinical, laboratory, and demographic data of all patients were obtained. Histopathological and direct immunofluorescence findings were further evaluated. The mean age (±standard deviation) was 22.5 ± 6.7 years with a range of 14-32 years. The most common underlying disorder of AA renal amyloidosis was Tuberculosis (TB) (88.88%, 8/9) with cyclosporine induced in one of the cases (11.11%). In all nine cases, glomeruli were mostly enlarged with moderate to marked mesangial expansion with thickened arteries and arterioles due to deposition of pink hyaline acellular material. Renal amyloidosis is rare in young age and is mostly secondary in nature. The association of TB with renal amyloidosis is common in adults (3.6%-50%), but only infrequently reported in children. It is important, especially in developing countries to be aware, as successful treatment of TB can result in remission of nephrotic syndrome due to secondary renal amyloidosis.