Neuroradiology Case of the Month

October 2002

Jose A. Echeverri, MD, Akio Hiwatashi, MD,Toshio Moritani, MD, PhD,
Ahmed Abdelhalim, MD, Lawrence Buadu, MD, PhD, and Sven Ekholm, MD, PhD

Clinical Presentation: A 30-year-old male with a one week history of intermittent numbness in his tongue and right upper extremity, presented with generalized seizures. The patient had bilateral cervical and inguinal lymphadenopathies and was symmetrically hyperreflexic in the upper and lower extremities.

Imaging Findings: CT showed patchy white matter hypointensities in the left frontal lobe without enhancement or mass effect (Fig. 1).

Figure 1: Postcontrast head CT: Ill-defined area of hypodensity is visualized in the base of the left frontal lobe.

Figures 2-4: Head MRI:

Figure 2: Coronal FLAIR (TR: 10002, TE: 142.5, T.I.: 2200): There are hyperintense lesions involving cortex and subcortical white matter of the frontal (A,B) and temporal lobes bilaterally, and the left hypothalamus (B).
Figure 3: Axial T2WI: (TR: 5400, TE: 98) Hyperintense lesions of cortex and subcortical white matter in the medial aspect of the frontal lobes bilaterally, extending posteriorly to the left hypothalamus.
Figure 4: : Axial post contrast T1 WI (TR: 650, TE: 20): Enhancing lesions in the left hypothalamus (A), left temporal and both frontal lobes (B,C).

Figures 5-6: CT of the Chest, Abdomen and Pelvis:
Extensive lymphadenopathy in multiple areas including neck base, bilateral hila, mediastinum, retroperitoneum, mesentery and pelvis.

Figure 5A: Enlarged lymph nodes are seen in the lower pretracheal, AP window and preaortic window.	Figure 5B: Subcarinal enlarged lymph node is also visualized.
Figure 6: Scattered lung nodules.

Hospital Course: The patient was initially given phenytoin. A surgical biopsy of one of the inguinal nodes revealed noncaseating granulomas without acid fast or fungal organisms. Flow cytometry was also performed and the findings were rather consistent with sarcoidosis. Ophthalmologic examination revealed vascular sheathing and retinal vasculitis that are consistent with sarcoidosis. The patient was placed on prednisone.

Diagnosis: Sarcoidosis with CNS involvement.

Discussion: Sarcoidosis, histologically characterized by non-caseating granulomas, is a multisystemic idiopathic granulomatous disease of unknown cause. Lymph nodes, lungs, skin, eyes and bone are frequently involved [1]. Neurologic manifestations of sarcoidosis include meningoencephalopathy, cranial neuropathy, hypothalamic dysfunction, hydrocephalus, myelopathy and peripheral neuropathy [1]. Radiologically, it can present in many different ways, including dural mass or thickening, leptomeningeal granulomas, brain parenchymal lesions, and cranial nerve, spinal cord and nerve root involvement [2]. Basal granulomatous meningitis causes most of the CNS manifestations either by infiltration or compression of adjacent structures [4]; the infundibulum, the floor and anterior walls of the third ventricle, and the base of the frontal lobes are frequently involved [1].

CNS sarcoidosis has been reported in approximately 5% of patients with sarcoidosis [2,3].

The diagnosis of neurosarcoidosis is based on the documentation of systemic sarcoidosis and exclusion of other neurologic diseases.

Dural mass lesions tend to be isointense with gray matter on T1 weighted MR images, hypointense on T2, and enhance uniformly with intravenous gadolinium. Differential considerations include meningioma, lymphoma, adenocarcinoma, chronic meningitis such as Wegener's, idiopathic hypertrophic cranial pachymeningitis, and granulomatous infection. Dural sarcoidosis is often focal and has non-necrotizing epithelioid granulomas [2].

Leptomeningeal sarcoidosis is associated with enhancing brain parenchymal lesions (80%) and cranial nerves (60%). Leptomeningeal infiltration typically involves the suprasellar and frontal basal meninges. The granulomatous lesions may coalesce to form mass-like lesions, mainly in the region of the optic chiasm, floor of the third ventricle and pituitary stalk. The differential diagnosis of this leptomeningeal involvement includes tuberculosis, Wegener's granulomatosis, fungal and pyogenic meningitis, leptomeningeal lymphoma, demyelination, meningioangiomatosis, acute lymphocytic leukemia and leptomeningeal carcinomatosis [2].

Diffusely enhancing intraparenchymal granulomas can be found in the hypothalamus, brainstem, cerebral and cerebellar hemispheres [2]. They are isodense with gray matter on non-contrast enhanced CT. On MRI, they are isointense to gray matter on T1WI and iso- to hyperintense on T2WI [1].

Nonenhancing intraparenchymal lesions are more frequently found in the periventricular white matter, but also in the brainstem and basal ganglia. The former are thought to result from periventricular granulomas or from areas of infarction due to granulomatous angiopathy [2].

Clinical involvement in sarcoidosis has been described of all the cranial nerves. The facial nerve is the most frequently involved, usually presenting as Bell's palsy.

Spinal cord lesions tend to be extramedullary. The cervical spine is frequently involved. Imaging findings are nonspecific, and the differential diagnosis includes multiple sclerosis, tumor, vacuolar myelopathy, tuberculosis and fungal infection [2].

References:

1. Barkovich AJ: Pediatric Neuroimaging. Philadelphia, PA: Lippincott Williams & Wilkins; 2000; 715-770.
2. Christofidis GA, Spickler EM, Recio MV, Mehta BM. MR of CNS Sarcoidosis: Correlation of Imaging Features to Clinical Symptoms and Response to Treatment. AJNR 1999; 20: 655-669.
3. Dumas J-L, Valeyre D, Chapelon-Abric C, Belin C, Piette J-Ch, Hamdane T-L, Brauner M, Goldlust D. Central Nervous System Sarcoidosis: Follow-up at MR Imaging during Steroid Therapy. Radiology 2000; 214: 411-420.
4. Delaney P, MD. Neurologic Manifestations in Sarcoidosis. Ann Int. Medicine 1977; 87: 336-345.