Cerebral Abscess: This is often characterized by a ring-enhancing lesion with significant perilesional edema on CT scans. The ring enhancement is due to the body's attempt to encapsulate the infection, and the edema is a result of the inflammatory response.

Glioblastoma: A primary brain tumor that can appear as a ring-enhancing lesion with surrounding edema due to its aggressive nature and necrotic center.
Metastatic Brain Tumor: Similar to glioblastoma, metastases can present as ring-enhancing lesions, especially if they are necrotic, with significant perilesional edema.
Subacute Ischemic Stroke: In some cases, a subacute ischemic stroke can present with a ring-like appearance due to the evolution of the infarct, though this is less common.

Cerebral Toxoplasmosis: Especially in immunocompromised patients, toxoplasmosis can present with multiple ring-enhancing lesions and is critical to diagnose due to its treatable nature.
Neurocysticercosis: While often presenting with multiple lesions at different stages, a single ring-enhancing lesion with edema can be seen, particularly in the colloidal vesicular stage.
Primary Central Nervous System Lymphoma (PCNSL): Though typically presenting with solid enhancement, PCNSL can rarely appear as a ring-enhancing lesion, especially if there is central necrosis.

Mucormycosis (Rhino-Orbital-Cerebral): A rare but aggressive fungal infection that can invade the brain and present with ring-enhancing lesions, particularly in diabetic or immunocompromised patients.
Cerebral Granuloma: Can be due to various causes including tuberculosis, sarcoidosis, or other granulomatous diseases, presenting as a ring-enhancing lesion with surrounding edema.
Hemorrhagic Metastasis: Some metastatic brain tumors can bleed, leading to a ring-like appearance on CT due to the hemorrhage surrounded by edema.