A Rare Incidental Finding of Erdheim-Chester Disease

Introduction: Erdheim–Chester Disease (ECD) is a rare non-Langerhans histiocytic disorder marked by histocyte overproduction and tissue infiltration affecting the retroperitoneum, large vessels, heart, lung and central nervous system. Clinical presentation is nonspecific and varies depending on the organ involved. Here we report an incidental case of ECD in a patient with acute kidney injury (AKI). Case Description: A 77-year-old white male with coronary artery disease, heart failure, and tobacco use presented for facial and shoulder burns after cardiac syncope and fall onto a space heater. He was found to have enterococcus faecalis bacteremia with right aortic valve vegetation, AKI and pulmonary embolism. Incidentally, CT abdomen pelvis showed irregular symmetric soft tissue infiltration of bilateral perirenal spaces, known as “hairy kidney” appearance, modest bilateral pelviectasis and soft tissue thickening surrounding the thoracic and intra-abdominal aorta (Fig. 1). Initial creatinine was 1.79 mg/dl which increased to 5.32 mg/dl in 24 hours. Biopsy of the lesion was deferred due to anticoagulant requirements and rapid clinical decline with volume overload and mental status changes. He was on hemodialysis briefly and transitioned to hospice per family wishes. Radiological features in this case, including the “hairy kidney” appearance, periaortic soft tissue, sparing of the vena cava and ureters, interlobular septal thickening and pleural effusion, are characteristic for ECD and support the diagnosis. Discussion: ECD is a multiorgan disorder marked by sclerotic lesions of the long bones and perirenal infiltration. Less than 10% of cases occur without bone lesions, necessitating the consideration of histopathology and radiological characteristics for diagnosis. Given the nonspecific nature of ECD, early recognition of the radiological presentations as in our patient is crucial for timely diagnosis and management. Recent discoveries of underlying mutations, like the common BRAFV600E mutation, have shaped the use of targeted therapies such as BRAF inhibitors to prevent disease progression.