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