A case of Erdheim Chester disease with central nervous system involvement.

Erdheim Chester disease (ECD) is a rare non-Langerhans cell histiocytosis, commonly involving the musculoskeletal system. Other tissue can also be involved, including the central nervous system with wide spectrum of clinical features, at times being nonspecific. This can cause diagnostic dilemmas with delay in diagnosis and initiation of therapy. Here we describe a 63-year-old man who had presented with ataxia and behavioral changes, bony pains, weight loss, and fatigue. His computed tomography (CT), 99Tc scintigraphy and histopathological features on bone biopsy were consistent with ECD. Thus, ECD should be considered as a differential diagnosis in patients presenting with bony pain and nonspecific features of multiorgan involvement.