When CKD Isn't What It Seems: A Case of LECT2 Amyloidosis

Introduction: LECT2 (leukocyte chemotactic factor 2) amyloidosis is a rare and underrecognized cause of chronic kidney disease (CKD), particularly in individuals of Hispanic, especially Mexican, descent. It typically presents with slowly progressive CKD, bland urine sediment, and subnephrotic proteinuria—features that complicate timely diagnosis. Recognition is critical, and kidney biopsy remains the diagnostic gold standard. Case Description: A 77-year-old Hispanic male with hypertension, hyperlipidemia, heart failure with preserved ejection fraction, and recent coronary artery bypass grafting was referred for evaluation of stage III CKD and persistent hyperkalemia. Over three months, he reported fatigue, joint pain, and 12-pound unintentional weight loss. Physical exam was unremarkable, with no edema, organomegaly, or systemic findings. Labs showed eGFR decline from 43 to 34 mL/min/1.73 m2, creatinine 1.85 mg/dL, BUN 27 mg/dL, potassium 5.5 mmol/L, and hemoglobin 12.3 g/dL. Urinalysis was bland, with 24-hour urine protein of 352 mg and albumin/creatinine ratio of 136 mg/g—consistent with subnephrotic proteinuria. ANA was positive, dsDNA mildly elevated (10 IU/mL), and complements normal. SPEP/UPEP showed no monoclonal proteins. Renal ultrasound was unremarkable. Kidney biopsy revealed Congo red and thioflavin T-positive amyloid deposits. Immunohistochemistry confirmed LECT2 amyloid. Histology showed ~30% interstitial fibrosis, tubular atrophy, and global glomerulosclerosis. Supportive management was initiated. Discussion: LECT2 amyloidosis is an uncommon but important cause of progressive CKD in Hispanic patients. Its slow course, bland urine, and absence of systemic signs can obscure diagnosis. Unlike AL or AA amyloidosis, LECT2 is not associated with monoclonal gammopathy or inflammation. This case highlights the critical role of biopsy with Congo red staining and immunohistochemistry in identifying LECT2. There is no targeted therapy. Management is supportive, focusing on blood pressure and CKD progression. Early recognition helps avoid unnecessary testing and guides appropriate care. Take-Away Lessons Suspect LECT2 in older Hispanic patients with unexplained CKD and bland urinalysis. Subnephrotic proteinuria and absence of systemic symptoms complicate diagnosis. Biopsy with Congo red staining and immunohistochemistry is key. Treatment is supportive; no disease-specific therapy exists.