18F-FDG PET/CT in Erdheim–Chester disease

Excerpt

We feature a 50-year-old woman with a 4-month clinical picture of vertigo, hand paresthesias and left hemicranial headache. She was hospitalized following her referral of binocular diplopia and syncopes. The practiced angioTAC, showed a 2-cm intra-carotideal lesion that caused compression and displacement of the artery, as well as homolateral jugular tapering and thickening of the abdominal aortic wall. Takayasu’s arteritis was suspected. An 18F-FDG PET/CT study was requested. PET images show a marked increase in metabolic activity on the perivascular region of the carotids, thoracic, abdominal, and iliac aorta (Fig. 1a,b,c) [1]. In addition, there is a pathological increase in the metabolic activity in the bone marrow of long bones, emphasizing the lower half of both femurs, and hypermetabolic lesions in the vertebrae (Fig. 1 arrow). These findings suggested Erdheim–Chester disease (ECD) as the first probable diagnosis. We recommended the lower third of femurs as the optimal biopsy site. The anatomopathological result shows a lesion with predominance of xanthogranulomatous histiocytes compatible with ECD without BRAF mutation. ECD is an uncommon non-Langerhans cell histiocytosis. The etiology and pathogenesis are still unknown. The diagnosis relies on established imaging and histological criteria [2]. The bone involvement is almost universal, which is usually combined with infiltration of at least one more organ system. The most common manifestation is a mixed pattern with lytic and sclerotic lesions in long tubular bones. 18FDG-PET/CT was particularly useful for assessing the extent of disease, locate the optimum site for biopsy and treatment response evaluation [3‐5].

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