Differential Diagnosis for Diffuse Meningeal Enhancement on MRI
Single Most Likely Diagnosis
- Meningitis: This is the most common cause of diffuse meningeal enhancement on MRI, as it leads to inflammation of the meninges, which can be viral, bacterial, or fungal in origin. The enhancement is due to the breakdown of the blood-brain barrier and increased blood flow to the inflamed areas.
Other Likely Diagnoses
- Neoplastic Meningitis: Also known as leptomeningeal metastases, this condition occurs when cancer cells spread to the meninges, leading to diffuse enhancement on MRI. Common primary cancers include breast, lung, and melanoma.
- Sarcoidosis: A systemic granulomatous disease that can affect the meninges, leading to diffuse enhancement on MRI. It is often associated with other systemic symptoms such as lung involvement and skin lesions.
- Multiple Sclerosis: Although more commonly associated with white matter lesions, multiple sclerosis can also cause meningeal enhancement, particularly in the early stages of the disease.
Do Not Miss Diagnoses
- Subarachnoid Hemorrhage: Although often associated with more focal findings, subarachnoid hemorrhage can cause diffuse meningeal enhancement, particularly if the blood is diffuse and not localized to a specific area.
- Infectious Diseases (e.g., Tuberculosis, Fungal Meningitis): These conditions can have a high mortality rate if not promptly diagnosed and treated. They may present with diffuse meningeal enhancement on MRI, particularly in immunocompromised patients.
- Carcinomatous Meningitis: Similar to neoplastic meningitis, but with a more aggressive clinical course and poorer prognosis.
Rare Diagnoses
- Rheumatoid Arthritis: A systemic autoimmune disease that can rarely cause meningeal enhancement on MRI, often in association with other systemic symptoms such as joint inflammation and skin lesions.
- Lyme Disease: A tick-borne illness that can cause meningeal enhancement on MRI, particularly in the early stages of the disease.
- Histocytosis: A rare group of diseases characterized by the abnormal proliferation of histiocytes, which can cause meningeal enhancement on MRI, particularly in the context of Langerhans cell histiocytosis.