Presentation
Intellectual disability, no history of convulsion.
Patient Data
An incidental noted, a sharply circumscribed indolent-appearing iso-intense relative to CSF intensity protrusion into the left side of the posterior calvaria or a dural venous sinus causing a filling defect in the left transverse dural venous sinus with small pedicle. It reflects a high T2 and low T1 signal with no contrast enhancement. Measure about 14 mm in diameter. Typical of giant arachnoid granulations.
Another one is similar but it is tiny noted at the right side (normal variant).
Axial T2WI shows a large arachnoid granulation in the left transverse sinus with two internal septations (large red arrow) typical of giant arachnoid granulations. Another one is similar but it is tiny noted at the right side (small red arrow).
Case Discussion
This is an excellent example of an incidentally noted typical giant arachnoid granulation, otherwise unremarkable enhanced MRI brain study.
Arachnoid granulations are outpouchings of the arachnoid membrane which extend into the dural sinuses or calvarium, surrounded by a capsule of dense connective tissue.
The typical radiological features of the granulations: CSF-like signal intensity on all sequences, a blood vessel within the lesion and bone erosion. Typically, they range from 2 to 8 mm and occasionally can exceed 1 cm in diameter.
It is essential to distinguish these benign giant arachnoid granulation from more serious dural venous sinus pathology such as thrombosis and neoplasms to avoid unnecessary invasive procedures.
Unable to process the form. Check for errors and try again.