A Case of Primary Colon Carcinoma Demonstrated by FDG PET/CT Imaging After Detection of a Solitary Brain Metastasis

Abstract

The detection of brain metastases as the initial manifestation of colorectal carcinoma without liver or lung involvement is extremely rare. Herein we present a case of a 52-year-old male patient with an unusual presentation of colon cancer, with primary lesions demonstrated by fluorine- 18-labeled fluorodeoxyglucose (FDG) Positron-emission tomography/computed tomography (PET/CT) after detection of a solitary brain metastasis. Brain CT images revealed a brain tumor. Histopathologic evaluation indicated metastatic poorly differentiated adenocarcinoma, while his physical examination was normal. The PET/CT revealed abnormal intense FDG uptake in the right parietal region and in descending colon, with no other abnormal FDG uptake elsewhere in the body. The histopathologic diagnosis of the descending colon lesion revealed moderately differentiated adenocarcinoma. This case indicates that FDG PET/CT imaging may have a positive impact on the evaluation of patients with brain metastasis from an unknown primary.