September 25, 2019
The patient is a 75-year-old Hispanic male who presents with progressively worsening kidney function and a creatinine of 1.6 mg/dl (baseline 1.0 mg/dl). His physician called for a biopsy due to a slowly “creeping” creatinine over the last 8 months. Images 1 & 2 show “apple-green birefringence” on a Congo red stain under polarized light within the interstitium. Image 3 shows mild interstitial fibrosis. Image 4 shows a normal glomerulus on PAS stain and Image 5 shows positive immunohistochemical staining with Lect2.
Leukocyte cell-derived chemotaxin 2 (ALECT2) amyloidosis preferentially affects Hispanics (particularly Mexicans) as well as Punjabis, First Nations people in British Columbia, Egyptians, and Native Americans. Most patients are elderly and present with chronic kidney disease and bland urine sediment. ALECT2 amyloidosis usually affects the liver and kidney, sparing the heart and adipose tissue. Within the kidney, there is usually involvement of the cortical interstitium with sparing of the medulla. The pathogenesis of ALECT2 amyloidosis is unknown. In general, patients with ALECT2 amyloidosis have better overall survival than those with AL or AA amyloidosis. There are no specific therapies for ALECT2 at this time and approximately 40% of patients progress to ESKD.