Corpus mammilare lipoma as a pitfall for MR Angiography of the basilar artery

A 48 year old patient reported multiple episodes of visual dysfunction with tunnel vision, dysesthesia, dysarthria and dull headache over a period of two years. As the neurological state does not detect abnormalities, a transient ischemic attack of the posterior circulation was diagnosed. Taking into account the age of the patient etiologically a posterior circulation aneurysm was more presumably than a atherosclerotic stenosis. As an incident finding a lipoma of the corpus collosum was found by magnetic resonance imaging. Particularly with regard to the signal intensity of the time-of-flight angiograms, and a contact to the head of the basilar artery a thrombosis aneurysm also has to be considered for differential diagnosis. Because there were no relevant radiological findings the final diagnosis was a basilar migraine based on the clinical picture. This case demonstrates that the partly unspecific signal intensity of magnetic resonance images could lead to misinterpretations. To avoid misdiagnoses even uncommon anatomic variants should be considered for differential diagnosis. This applies also, if the first impression of radiological images corresponds quiet well with the clinical picture.