Leukocyte Chemotactic Factor 2-Related Amyloidosis Presenting with a Rash and Unexplained CKD

Introduction: Leukocyte chemotactic factor 2 amyloidosis (ALECT2) is a recently described type of amyloidosis predominantly affecting the kidneys. ALECT2 has a relatively benign course, rare cardiac involvement, and a specific ethnic distribution. Recognizing ALECT2 is crucial to avoid unnecessary and potentially harmful treatments intended for more common subtypes like AL or AA amyloidosis. We present a case of ALECT2 with unusual clinical presentation and renal histology. Case Description: A 60-year-old Hispanic female with a history of prediabetes (HbA1c = 5.7%) and hypertension presented with a pruritic skin rash on her hands. Upon reviewing historical laboratory findings, the patient was found to have elevated serum creatinine (Cr = 1.20 mg/dL) with an estimated glomerular filtration rate of 48 mL/min/1.73m2 (CKD stage 3) without proteinuria for the past 20 months. Renal ultrasound showed increased echogenicity consistent with CKD. Despite controlling her hypertension, her serum creatinine continued to rise (1.39 mg/dL) over the next 2 months, necessitating a biopsy to investigate the underlying etiology of her CKD. The kidney biopsy revealed LECT2 amyloidosis, predominantly glomerular and less dominant interstitial amyloid deposition, which was Congo red-positive with light green birefringence under polarized light (Image1). No diagnostic features of paraprotein-associated renal deposition disease, immune complex-mediated glomerulonephritis, or interstitial nephritis were observed, and urine protein electrophoresis was negative. The echocardiography did not suggest cardiac involvement with an ejection fraction of 60-65%. Discussion: We report an unusual case of biopsy proven ALECT2 presenting with skin rashes resembling other autoimmune diseases.