Erdheim-Chester Disease

Clinical History

42-year-old woman presented with chronic and progressive bone pain.

Imaging Findings

The patient presented with a one year history of progressive appendicular bone pain, exertional dyspnoea and weight loss of 10 kg. Radiographic examination showed bone alteration of the disease, with bilateral and symmetric sclerotic lesions along the diaphysis and metaphysis of femur, tibia fibula and humerus (fig 1). CT scan of knees showed diaphyso-metaphyseal and epiphysis lytic lesion (fig 2). Knees MR examination showed replacement of the normal marrow by an infiltrative process involving the diaphyses, metaphyses and portions of epiphysis in the femur, tibia and fibula. This process was in low-signal-intensity on T1-weighted (fig 3), intermediate-signal-intensity on T2-weighted (fig 4) and without contrast enhancing. Adjacent soft tissues were normal. Chirurgical bone biopsy was performed. Histological examination showed histiocytes, with lymphocytes and eosinophils. The histiocytes stained for CD68, and were negative for CD1a. This immunophenotype combined with the morphological features was highly suggestive of Erdheim-Chester disease. Chest X-ray and thoracic CT scan demonstrated a pulmonary fibrosis (fig 5). Prednisolone 40 mg/day was started with adriamycin. Relative stability was maintained for over 6 months, followed by symptomatic and functional respiratory deterioration.

Discussion

Erdheim-Chester disease is a rare sporadic systemic histiocytic disorder of unknown cause. In 1930, Chester reported two cases of what he referred to as “lipoidgranulomatosis”. Two patients had symmetric sclerosis at the diamataphyseal portions of the lower extremities, with additional extraskeletal involvement in one (1). Distinction between Erdheim-Chester disease and Langerhans cell histiocytosis can be difficult at light microscopy. Both lesions consist of multinucleated giant cells and histiocytes (1). Differential diagnosis is based on immunohistochemistry; CD1a and CD68 are specific markers for Langerhans cells and Erdheim-Chester disease, respectively. Althout the pathogenesis of Erdheim-Chester disease remains unclear; a recent study suggested its neoplasic nature is due to monoclonal proliferation of histiocytes (2). The xanthogranulomatous process infiltrate bone tissue, but can infiltrate the central nervous system, orbits, viscera, retroperitoneum, and superficial soft tissues. Age at diagnosis ranges from 7 to 84 years, with a male-to-female ratio of 1:3. The most common presentation is bone pain, followed by diabetes insipidus, exophtalmos, retroperitonel mass and pulmonary or cardiac involvement (1, 3, 4). The key to diagnosing Erdheim-Chester disease is recognizing the typical pattern of symmetric diametaphyseal medullary sclerotic lesions of the appendicular skeleton. Radiographic examination shows the typical bone alterations of the disease, with bilateral and symmetric sclerotic lesions along the diaphysis and metaphysic of tubular bones such as femur, tibia, fibula, humerus, radius and ulna. MR imaging examination of the appendicular skeleton show replacement of the normal marrow by an infiltrative process involving the diaphyses, metaphyses, and portions of epiphysis in long bone. The process has a low-signal-intensity on T1-weighted and hight-signal-intensity on T2-weighted (3). Treatment options are varied and include corticosteroids, chemotherapy, radiation therapy, immunotherapy and surgery (1). The overall prognosis is difficult to assess, because so few cases have been reported, but the average reported survival has been 32 months after the initial diagnosis. The main causes of death are respiratory distress, pulmonary fibrosis, and heart failure (3).

Differential Diagnosis List

Final Diagnosis

Erdheim-Chester Disease

URL:	https://www.eurorad.org/case/5655
DOI:	10.1594/EURORAD/CASE.5655
ISSN:	1563-4086