Utility of 18F-FDG PET/CT in Assessment of Disease Extent and Response to Treatment in Xanthoma Disseminatum.

The clinical utility of 18F-FDG PET/CT is being increasingly recognized in histiocytic disorders. We report the case of a 23-y-old woman who presented with slowly progressive, yellowish-brown papules, plaques, and nodules over her face and flexures. Besides the multiple cutaneous lesions, lesions of the brain, stomach, gallbladder, and marrow were additionally revealed by baseline 18F-FDG PET/CT. Skin biopsy and the overall clinical picture were consistent with xanthoma disseminatum. Subsequent PET/CT after cladribine therapy revealed a decrease in the extent and metabolic activity of most lesions, suggestive of a favorable response. This case report highlights the potential role of 18F-FDG PET/CT in the accurate assessment of disease extent and posttreatment response in rare histiocytic disorders.