Simultaneous middle fossa arachnoid cyst and ambient cistern epidermoid cyst: case report and endoscope-assisted...

Simultaneous occurrence of dual intracranial pathology is very rare. Most of such reported cases occur in the setting of a genetic or hereditary predisposing condition like neurofibromatosis. Though some cases of coexistence of multiple intracranial pathologies have been reported, occurrence of an arachnoid and epidermoid cyst in the same patient has never been reported. A 16-year-old boy was referred to us with a diagnosis of left temporal arachnoid cyst. Careful review of the MRI showed the presence of 2 different signal intensities with restricted diffusion in the cyst in the ambient cistern and normal diffusion in the cyst anterior to the temporal tip suggesting the presence of an arachnoid cyst adjacent to an epidermoid cyst which was managed using endoscope-assisted microsurgical transcranial surgery. The possibility of such an association could be explained based on the congenital origin of both lesions. Diffusion-weighted imaging can be invaluable in unraveling such a relationship.