Renal ALECT2 Amyloidosis: A Clinicopathologic Study of 17 Patients
Samar M Said, Sanjeev Sethi, Lynn D Cornell, Mary E Fidler, Ahmet Dogan, Samih H Nasr. Mayo Clinic, Rochester, MN
Background: Amyloidosis derived from leukocyte chemotactic factor 2 (ALECT2) is a newly identified form of amyloidosis that primarily affects the kidney and it is now the third most common type of renal amyloidosis. Only one clinicopathologic series of 10 ALECT2 patients has been reported so far. Here, we describe the clinical features, pathologic findings, and outcome of 17 patients with renal ALECT2.
Design: We identified 17 cases of ALECT2 from our pathology archives, between 2007-2012. In all cases, amyloid deposits were Congo-red positive and showed apple green birefringence when viewed under polarized light. Amyloid typing was done by laser microdissection/mass spectrometry in all cases.
Results: The cohort consisted of 9 males and 8 females with a mean age at diagnosis of 67 yrs (range 56 to 81). All 17 patients were Hispanic and all 12 with available data were of Mexican origin. All patients presented with chronic renal insufficiency. Mean serum creatinine at renal biopsy was 2.9 mg/dL (range, 1.3-6.6). Proteinuria ranged from 0.04-11 g/day (mean 3.8 g/day). Mean serum albumin was 3.5 g/dL. Peripheral edema was present in 31% of patients, full nephrotic syndrome in 19%, and microhematuria in 19%. Histologically, all cases showed extensive interstitial involvement. Glomerular and vascular involvement were each present in 76% of patients and were mild in most patients. None of the cases showed glomerular amyloid spicule formation on silver stain or electron microscopy. The percentage of glomeruli with global sclerosis ranged from 0-92% (mean 44.6%). Tubular atrophy and intersitial fibrosis affected >50% of the cortex sampled in 59% of cases. Concurrent diabetic glomerulosclerosis was present in 3 patients and concurrent membranous glomerulopathy in 1 patient. Follow up data were available in 15 patients, two of whom died shortly after biopsy. After a mean follow up of 26 months (range, 5-60 months) in the remaining 13 patients, 6 (46%) progressed to ESRD. The time from biopsy to ESRD ranged from 1 week to 33 months (mean 12.7 months)
Conclusions: ALECT2 should be suspected in older individuals of Mexican origin who present with renal impairment and bland urinary sediment, regardless of the degree of proteinuria. Renal outcome is poor with close to half of patients progressing to ESRD within 2 years. Renal ALECT2 is characterized histologically by extensive interstitial involvement with less extensive and less frequent glomerular and vascular involvement.
Category: Kidney (does not include tumors)
Monday, March 4, 2013 1:00 PM
Poster Session II # 233, Monday Afternoon