An arachnoid granulation manifesting as a parietal protuberance in a 7-year-old child

A head protuberance caused by an arachnoid granulation

Abstract

An arachnoid granulation is an anatomical variant arising from a protrusion of the arachnoid through the dura mater. Arachnoid granulations usually measure a few millimeters in size. Some arachnoid granulations grow to fill and dilate the dural sinuses. Large granulations are designated giant arachnoid granulations. Giant arachnoid granulations are usually discovered as incidental findings, and solid protuberances in the parietal region caused by giant arachnoid granulations are not well known. A 7-year-old female child presented with a solid protuberance in the parietal region. Magnetic resonance imaging (MRI) revealed a giant arachnoid granulation. Thus, an arachnoid granulation can cause a parietal protuberance. MRI can be successfully performed without sedation when a child feels relaxed by the clinician’s explanation and initiatives such as prioritizing sequences that shorten the scan time and employing an open MRI system. Clinicians should be aware of an arachnoid granulation as a differential diagnosis for a parietal protuberance.