Imaging of Erdheim-Chester Disease

ERDHEIM‐CHESTER DISEASE (ECD) is a rare, sporadic, systemic, histiocytic disease of unknown etiology caused by infiltration of different organs. Bone involvement is constant. We present a patient with this disorder to illustrate skin lesions, bone X‐ray findings, and magnetic resonance (MR) images. A 59‐year‐old man was hospitalized because of fever and pain in his right knee. He had a 20‐year history of xanthomas on his face, eyelids, trunk, and extremities. Palpebral xanthomas were removed surgically on several occasions but recurred leading to keloid scars. Skin biopsies were performed on three occasions showing the presence of dense infiltration of the dermis with foamy histiocytes, fibroblasts, some multinuclear giant cells of the Touton type, and inflammatory cells. Histiocytic cells were negative for S‐100 protein and did not show Birbeck granules. Occasionally, he had experienced bone pain in the extremities over the last 10 years. Five years before, he had been treated with prednisone without any benefit. Family history was unremarkable with respect to this disease. On admission, his temperature was 38.2°C, pulse was 98, and blood pressure was 140/80. Disseminated skin xanthoma‐like lesions were observed on the face, trunk, and extremities, sometimes forming cutaneous masses (Fig. 1). Signs of arthritis were observed on the right knee, and urate crystals were found in joint aspirate. X‐ray examination of the right knee showed mixed lytic and sclerotic lesions in the metaphysis and diaphysis of the tibia and femur (Fig. 2). Similar lesions were observed in the radius, ulna, and humerus. Bone scanning with technetium 99 revealed symmetric and abnormally increased uptake of the distal part of the long bones. MR showed low‐intensity patchy marrow replacement imaging in tibial (Fig. 3) and radius diaphysis and metaphysis on T1 sequence, which was enhanced by gadolinium, and a mixed signal intensity on T2 sequences (Fig. 4). Serum concentrations of total and low‐density lipoproteins (LDL) cholesterol were low (111 mg/dl and 78 mg/dl, respectively) whereas apo A‐I (128 mg/dl), apo B (81 mg/dl), and lipoprotein (a) (10 mg/dl) were within the normal range. Dual‐energy X‐ray densitometry (QDR 4500; Hologic Inc., Waltham, MA, USA) at the lumbar spine (0.981 g/cm2; T = −1.00; Z = −0.39) and total hip (1.110 g/cm2; T = −0.48; Z = +0.40) was similar to that of age‐ and gender‐matched controls.