The differential diagnosis of a cerebral ring-enhancing lesion includes cerebral abscess, metastasis, glioblastoma and tumefactive demyelinating lesion (incomplete ring of enhancement).

No single feature is pathognomonic. Many features of the lesion, as well as clinical presentation and patient demographics, are needed to reach a final diagnosis. Conventional MR features and MR spectroscopy are of malignant neoplasia with features in favor of metastases include multiplicity and significant surrounding edema.

Lack of thin and regular wall and lack of central restricted diffusion excludes a cerebral abscess. Lack of incomplete ring of enhancement toward the cortex makes tumefactive demyelinating lesion.

Metastatic brain disease was suggested and survey for primary origin was recommended. The patient had a CT exam of the chest showing a right lower lung lobe mass with ipsilateral hilar and mediastinal lymphadenopathy. The patient had a CT guided biopsy from the mass revealing bronchogenic cancer (NSCLC).

Most cases of NSCLC will present in advanced stages. Brain metastases are found in up to a quarter of patients at presentation and are known as a common site of disease recurrence after an initial treatment response.