Unusual Case of Pseudomembranous Colitis Presenting as Fever of Unknown Origin Diagnosed by Tc-99m-HMPAO-labeled Leukocytes SPECT/CT.

The fever of unknown origin (FUO) represents a complex diagnostic challenge due to the wide range of etiologies that could cause it, including neoplastic, infectious, rheumatic/inflammatory, and miscellaneous disorders. Several nuclear medicine techniques have proven to be valuable tools for guiding etiologic diagnosis in the setting of FUO. One of these is technetium-99m (Tc-99m)-hexamethylpropylene amine oxime (HMPAO)-labeled leukocyte scintigraphy, which is a diagnosis method that allows in most cases the localization and evaluation of the extension of an occult infection. This paper presents an uncommon case of pseudomembranous colitis without diarrhea as etiology of FUO diagnosed by Tc-99m-HMPAO-labeled leukocytes.