Teaching Case

Nonspecific headaches

The patient had longstanding headaches. On MR imaging examination conventional T1 and T2-weighted sequences were acquired.

The most common locations for intracranial lipomas in decreasing order are interhemispheric fissure (pericallosal lipoma), superior cerebellar cistern, suprasellar cistern, cerebellopontine angle cistern, and sylvian cisterns. Intracranial lipomas are congenital lesions, and their occurrence has been attributed to maldifferentiation of the meninx primitiva, which embryologically fills the potential subarachnoid cisterns. Meninx primitiva is normally resorbed leaving behind subarachnoid cisterns, however, its incomplete resorbtion may result in a lipoma. It is well known that lipomas adjacent to the corpus callosum (pericallosal lipomas) usually interfere with normal callosal development leading to varying degrees of callosal dysgenesis. In the current patient a large lipoma, originating from the superior cerebellar cistern, similarly interfered with the development of the cerebellar vermis resulting in vermian dysgenesis. The patient had no symptom related with vermian dysgenesis. This can be explained by compansation of functions of the vermis by other parts of the cerebellum.