Tumefactive multiple sclerosis (MS) is a rare and more benign form of MS. Tumefactive MS cases are frequently misdiagnosed as glial tumors, because of the similarity of their clinical, radiological and histopathological findings. It is vital to prevent permanent neurological problems due to unnecessary invasive procedures or therapies. Tumefactive MS should be excluded before invasive diagnostic tests and therapies for the patients who are diagnosed as glial tumor. A 14-year old female was reported to have walking disability and vision loss. Two years ago, she had acute right hemiparesia and vision loss, cranial magnetic resonance imaging (MRI) revealed a large mass in the left hemisphere, histopathological investigation was compatible with glial tumor, and she was treated with chemotherapy and radiotherapy. At her last evaluation, there were no findings for glial tumor on cranial MRI, despite progressive clinical deterioration. Initial cranial MRI was reevaluated and tumefactive MS was diagnosed. This patients was presented to emphasize the importance of the differential diagnosis of tumefactive MS and glial tumor.

Keywords: <i>kafa içi kitle, beyin tümörü, glial tümör, tümefaktif lezyon, multipl skleroz.</i>