18F FDG PET/CT in a Rare Case of Erdheim–Chester Disease with Extensive Cutaneous and Skeletal Involvement

Erdheim-Chester disease (ECD) is a rare systemic non-Langerhans cell histiocytosis with multiple organ involvement. Being a rare disease with variable clinical manifestations, it is often difficult to diagnose. ¹⁸F-2-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) plays a vital role in assessing disease extent and severity, diagnosis, treatment response and is a potential biomarker for BRAF mutation. We present here a rare case of ECD with FDG PET/CT showing extensive cutaneous lesions apart from skeletal involvement.