The renal biopsy from this 79-year-old Hispanic male shows extensive glomerular, tubulointerstitial and vascular deposition of a PAS-pale (Fig 1), non-argyrophilic (Fig 2) and Congo red positive (Fig 3) amorphous material which shows apple green birefringence upon polarization, consistent with amyloid deposits. The amyloid deposits show no light chain restriction on immunofluorescence and electron microscopy shows numerous small, non-branching, overlapping fibrils within the glomeruli, interstitium, and vessels. An AA amyloid immunoperoxidase stain is negative; however, staining for LECT2 amyloid is strongly and diffusely positive (Fig 4). The aforementioned morphologic findings are characteristic of LECT2 amyloidosis. Although described relatively recently, it is now known that LECT2 amyloidosis is the third most prevalent form of renal amyloidosis and the most common form in Hispanic patients. In fact, an autopsy study focused on the Hispanic population of the southwest region of the United States demonstrated that up to 3.1% of these individuals are affected by renal LECT2 amyloidosis. The disease is not limited to the Hispanic population, and reports have been published in other ethnicities such as Egyptians. While currently, no specific treatment is available, identification of LECT2 amyloidosis as the cause of renal disease in affected patients is of utmost importance to better understand the disease and to avoid exposing the patient to unnecessary therapeutic regimens.
References:
1- Larsen CP, Walker PD, Weiss DT, et al. Prevalence and morphology of leukocyte chemotactic factor 2-associated amyloid in renal biopsies. Kidney Int. 2010; 77: 816-819.
2- Larsen CP, Kossmann RJ, Beggs ML, et al. Clinical, morphologic, and genetic features of renal leukocyte chemotactic factor 2 amyloidosis. Kidney Int. 2014; 86: 378-382.
3- Larsen CP, Ismail W, Kurtin PJ, et al. Leukocyte chemotactic factor 2 amyloidosis (ALECT2) is a common form of renal amyloidosis among Egyptians. Mod Pathol. 2016; 29: 416-420.
4- Larsen CP, Beggs ML, Willson JD, et al. Prevalence and organ distribution of leukocyte chemotactic factor 2 amyloidosis (ALECT2) among decedents in New Mexico. Amyloid 2016; 23: 119-123.
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