Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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August 23, 2018
Perisylvian lipoma associated with a left lentiform nucleus infarct
- Background:
- Intracranial lipomas are rare, accounting for <1% of all intracranial tumours. They are thought not be true neoplasms or hamartomas, but rather congenital lesions. Lipomas arise from persistence of the meninx primitiva, during the development of the subarachnoid cisterns, so blood vessels and cranial nerves can run across them.
- Lipomas are most commonly located in the interhemispheric/pericallosal region, accounting for half of all lipomas. Other locations are the quadrigeminal cistern/superior cerebellar cistern (25%), suprasellar/interpeduncular cistern (14%), cerebellopontine angle (9%) and Sylvian cisterns (5%).
- Relevant Clinical Information:
- Most of them are asymptomatic, but symptoms include headaches, epilepsy, and cranial nerve defects.
- This patient presented with lethargy; dense, right hemiplegia, marked right-sided facial droop, and a history of recent viral respiratory infection.
- Key Diagnostic Features:
- On CT they have low attenuation (-50 to -100 HU). They may be associated with calcification/ossification, especially when located in the interhemispheric location. On MR they will follow the signal of fat on all pulse sequences.
- Agenesis/dysgenesis of the corpus callosum is the most frequent brain anomaly associated with interhemispheric lipoma with cortical dysplasia, grey matter heterotopia, aneurysms, and arteriovenous malformations seen with lipomas in other locations.
- Causation and Potential Pathomechanisms:
- There are prior reports of lenticulostriate arteries stroke presumably related to a perisylvian lipoma
- The perforator stroke involved the lateral lenticulostriate arteries, arising from the lateral M1 segment, which the perisylvian lipoma overlies.
- Given the close spatial relationship, the presumed mechanism is transient occlusion of the arterial ostium or, less likely, by causing vasospasm of the subarachnoid segment of the lenticulostriate arteries.
- Differential diagnosis:
- Dermoid: Low attenuation on CT (<40 HU), high T1/T2 signal, midline, lobulated, no contrast enhancement, can rupture with subarachnoid dissemination.
- Epidermoid: Low attenuation on CT similar to cerebrospinal fluid. Low T1 and high T2 signal on MR. May suppress on FLAIR, but shows restricted diffusion.
- Teratoma: Usually more heterogenous in appearance and may show foci of contrast enhancement.
- Osteolipoma: Normally have central adipose and peripheral osseous tissues. Characteristically arises in the interpeduncular region and may have associated calcification.
- Subarachnoid clot or intramural hematoma: May appear similar due to high T1 signal. Fat saturated sequences are key help to distinguish both lesions.
- Other causes of childhood stroke: Other etiologies of childhood stroke must also be considered and excluded, including congenital heart disease, hematologic disease (i.e. sickle cell disease or prothrombotic disorders), inflammatory or noninflammatory vasculopathy, arterial dissection, metabolic disorders, and substance abuse. In particular, focal/transient cerebral arteriopathy, which may be related to prior infection (varicella or other), is an established cause of childhood stroke with a tendency to affect the lenticulostriate territory, and is an important differential diagnostic consideration in this case.
- Treatment
- Started on high-dose aspirin and antibiotics. Coagulation screen (negative), CSF serology (negative viral and bacterial studies), and normal cardiac echocardiogram. Physiotherapy and occupational therapy for rehabilitation resulted in improvement in facial droop and limb movements.
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