Spontaneous Rupture of Arachnoid Cyst in a Child: A Rare Case Report.

An arachnoid cyst is a benign lesion filled with cerebrospinal fluid that usually develops in the middle cranial fossa. The arachnoid cyst may become symptomatic if it has a large size or when it gets ruptured. Spontaneous rupture of an arachnoid cyst is a very rare complication. We report the case of an 11-year-old girl who was brought to the emergency department with a complaint of a progressive headache that was associated with vomiting. On examination, she was found to have papilledema. Subsequently, magnetic resonance imaging of the brain was performed to exclude any space-occupying lesion. The scan demonstrated a right extra-axial temporal lesion, measuring 7.8 x 5.4 x 4.9 cm on maximum dimensions, along with an extension to the right cerebral convexity in a crescentic shape. The lesion follows the signal intensity of cerebrospinal fluid on all sequences and exhibited no post-contrast enhancement or restricted diffusion. The lesion exerted a mass effect in the form of compression of the right temporal lobe. These findings were consistent with an arachnoid cyst with subdural hygroma. The patient was referred to the neurosurgery team. Then, the right temporal arachnoid cyst was drained through the right temporal craniotomy and the subdural hygroma was drained through a frontal Burr hole. The patient was seen after one month in the pediatrics clinic and was completely asymptomatic.