Focal areas of signal intensity (FASI) in neurofibromatosis type I

Case contributed by Ashesh Ishwarlal Ranchod


Known neurofibromatosis type I. Presented with bruising and is being worked up for ITP.

Patient Data

Age: 11 years
Gender: Female

There are multiple T2 and T2 flair hyperintense foci within the dentate nuclei, pons, middle cerebellar peduncles, midbrain including cerebral peduncles, and basal ganglia(globi pallidi). There is a mild increased T2 and T2 flair signal within the hippocampi and thalami additionally. There is no associated mass effect and no enhancement. ADC mapping is negative and confirms shine through relating to the T2 and T2 flair high signal intensity foci with no evidence of acute infarction or acute demyelination

There is ring enhancement within the fourth ventricle.

MRI brain is otherwise normal.


Case Discussion

This relatively asymptomatic child presents with known neurofibromatosis type I. Multiplanar and multiaxial MRI brain demonstrate multifocal and bilateral foci of signal intensity (FASI) as described above. These lesions are typically non-enhancing, with no mass effect and are likely to regress with age.

There are no other CNS features of neurofibromatosis type I on imaging of the brain.

There is an unusual ring-enhancing and elongated lesion within the fourth ventricle of uncertain etiology and significance. This is for further workup, neurosurgical assessment and discussion in the multidisciplinary meeting. Benign (infective/ racemose neurocysticercosis) and non-benign (ependymoma/medulloblastoma) including possible choroid plexus lesion or cyst are being considered.

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