Presentation
Incidental finding on CT trauma series
Patient Data
Motion affected study. No intracranial hemorrhage. 25 x 11 x 15 mm predominantly fat density lesion centered in the pineal region extending towards the right ambient cistern. There are peripheral foci of calcification. No evidence of acute established infarct. Grey white matter differentiation is preserved. The posterior fossa is unremarkable. Ventricular and sulcal morphology is within normal limits. The basal cisterns are clear. No calvarial or base of skull fracture. Orbits, paranasal sinuses and mastoid air cells are clear.
Conclusion: No acute intracranial injury identified. Incidental 2.5 cm pineal region predominantly fat density lesion with calcification. Differentials include an intracranial dermoid or teratoma. Further evaluation with MRI is recommended.
21 x 11 x 14 mm lesion within the quadrigeminal cistern to the right of midline, following fat on all sequences. No enhancement. Peripheral susceptibility artefact. Associated mass effect on the midbrain with anterior displacement. The remainder of the brain is normal with no diffusion restriction, signal abnormality or abnormal enhancement. The ventricular size and sulcal pattern is appropriate for the patient's age. The dural venous sinuses appear patent. Left maxillary sinus mucous retention cyst.
Conclusion: Quadrigeminal cistern lipoma.
Case Discussion
Intracranial lipomas are thought to reflect persistence and maldifferenitation of the meninx primitiva. The quadrigeminal cistern is the second most common location (after pericallosal), accounting for approximately 25% of intracranial lipomas. They may be associated with hypoplasia of the inferior colliculus or agenesis of the corpus callosum. The characteristic finding on both CT and MRI is a mass which has appearances consistent with fat.