A case of primary colon carcinoma demonstrated by FDG PET/CT imaging after the detection a solitary brain metastases

The detection of brain metastases as the initial manifestation of colorectal carcinoma without any liver or lung involvement is extremely rare. We present a case of a 52-years-old man with a rare colon cancer with primary lesions demonstrated by FDG PET/CT after the detection of a solitary brain metastasis. Brain CT images revealed a brain tumor. Histopathology indicated metastatic poorly differentiated adenocarci¬noma, while no abnormalities was detected during physical examination. PET/CT revealed abnormal intense FDG uptake in right parietal region and in descending colon and no other abnormal FDG uptake was observed elsewhere in the body. The pathological diagnosis of the lesion in the descending colon was moderately differentiated adenocarci¬noma. This case indicated that FDG PET/CT imaging may have positive impact on the identification of unknown primary tumor origins in the patients with brain metastases.