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Ruptured dermoid cyst with aseptic chemical meningitis

Case contributed by Ammar Haouimi
Diagnosis almost certain

Presentation

Sudden onset of headaches and nausea.

Patient Data

Age: 25 years
Gender: Male

There is an extra-axial complex midline mass of retrocerebellar location, ruptured within the subarachnoid spaces and ventricular system. It appears of non-homogeneous high signal intensity on T1WI, T2WI, and FLAIR, with no enhancement following IV contrast and attenuated on suppressed fat sat sequence. 

Dilatation of the ventricular system (3rd and lateral ventricles) with a fat-fluid level within the frontal horns as well as a "black boundary artifact". The fatty material appears hyperintense on T1WI, T2WI, and FLAIR, floating on the CSF and attenuated on the suppressed fat sequence. Small droplets of high signal intensity on T1WI, T2WI, and FLAIR attenuated on T2*, disseminated within the subarachnoid spaces (subarachnoid seeding), indicating an aseptic chemical meningitis.

Note small subcutaneous occipital tract sinus.

Case Discussion

MRI features of a ruptured dermoid cyst within the ventricular system and subarachnoid spaces with aseptic chemical meningitis.

Additional contributor: R Bouguelaa, MD.

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