Neurosarcoidosis

Findings

There is demonstrate diffuse, nodular meningeal thickening and enhancement along the convexities, interhemispheric fissures, and skull base. There is associated underlying parenchymal edema within the frontal lobes.

Differential diagnosis
- Granulomatous disease (namely, sarcoid)
- Meningitis
- Metastases
- Meningioma
- Histiocytosis


Diagnosis: Neurosarcoidosis (dural and parenchymal involvement)


Key points

Multisystem inflammatory disease characterized by noncaseating epithelioid-cell granulomas; etiology unknown
CNS involved in 5% clinically (27% autopsy); 10-20 per 100k in North America

Involves
- Dura, leptomeninges, subarachnoid space
- Brain parenchyma to include hypothalamus>brain stem>cerebral hemispheres>cerebellar hemispheres

Solitary or multifocal CNS mass(es)
Approximately 50% have periventricular T2 hyperintense lesions
Perivascular infiltrative involvement Virchow Robin spaces
May induce a small vessel vasculitis

Clinical Presentation:
- Most common symptom - CN deficit(s); most often CN VII; up to 50% asymptomatic
- Age of onset – 3rd-4th decade; 3-5% children; M:F 2:1; African American: Caucasian 10:1
- Pulmonary involvement in >90% of patients (abnormal CXR in association with CNS involvement strong evidence)

Course/Treatment:
- 2/3 have self limited monophasic illness; remainder have chronic remitting-relapsing course
- No known cure


Radiology

CT:
- May show basilar leptomeningeal enhancement
- Osteolytic skull lesions

MR:
- T1 + Contrast
Wide spectrum of enhancement
1/3 have multiple parenchymal lesions
>1/3 have leptomeningeal involvement, nodular and/or diffuse
10% solitary intra-axial mass
5-10% hypothalamus, infundibular thickening
- FLAIR:
Approximately 50% with periventricular T2 hyperintense lesions
Hyperintense vasogenic edema secondary to perivascular infiltrates or small vessel vasculitis
- T2:
Lacune (brainstem, BG)
Hypointense material within subarachnoid space
Hypointense dural lesion(s)
Hydrocephalus