Abstract
We report a case of metastatic brain tumor which showed hypointense on a T2-weighted MR image. A 69-year-old man was hospitalized because of sensory aphasia and right hemiparesis. He had a history of sigmoid colon cancer at 68 years old. CT scans revealed a high density tumor on the left temporal lobe. The tumor exhibited iso- and low-intensity signals on T1- and T2-weighted MR images, respectively. The marginal portion of the tumor showed an irregular enhancement upon Gd-DTPA administration. Fronto-temporal craniotomy was performed and the tumor was totally removed. In the pathological findings, it was found that the tumor was composed of relatively differentiated adenocarcinoma cells, indicating a metastatic brain tumor from sigmoid colon cancer. No evidence of acute hemorrhage or calcification was identified. We also confirmed the presense of mucin in the ducts of gland epithelium using PAS and alcian blue stain. The binding of mucin to water results in an increase in the amount of bound water, thereby slowing the tumbling rate of protons in the tissue, and causing the subsequent preferntial T2 shortening. Among lesions showing hypointensity on T2-weighted MR images, we have to be aware of the possibility of metastatic adenocarcinomas from the digestive system, besides melanoma, hemorrhage and calcification.
