We read with great interest the article by Cerase et al. [1] on the regression of dilated perivascular spaces (DPVS) of the brain. They reported that the most common location of such spaces is along lenticulostriate arteries and that their differential diagnosis includes an extensive list of diseases such as lacunar infarctions, fungal and parasitic infections, and cystic neoplasms [1]. They successfully noted that some cases reported as ‘‘cysts’’ might have been DPVS [1]. We agree and we would like to comment on the differential diagnosis of such spaces, based on a case from our experience where DPVS appeared as cysts within the frontal lobe. Carrying out a neuroanatomical study in our Department, we found (in a coronally sectioned middle-aged male brain) a cystic cavity placed into the lateral putamen (Fig. 1) and a few small cysts in the white matter above the striatum. The cavity, full of a transparent fluid, appeared as an oval hole with a 9 mm diameter. The putamen around the cavity appeared discoloured, probably because of the space-occupying effect of the cystic lesion. This discolouration extended medially to the internal capsule. Other cysts appeared in the white matter above the striatum. Inside the inferior part of the larger cavity there was a diaphragm forming a vesicle. Maximum dimensions of the main lateral putamen lesion were 15 9 14 9 8 mm. All the observed cysts appeared in the left middle cerebral artery territory. Micropathological examination confirmed the DPVS diagnosis. Cysts are common findings at brain imaging [4]. The commonest causes include vascular diseases, infections and tumours [2–5]. Neurocysticercosis occurs in 75% of all cases of systemic cysticercosis [4] and is the commonest worldwide parasitic brain infection. It causes mainly parenchymal cysts with transparent liquid [2]. Cysts may be multiple but do not typically occur in clusters [4]. Toxoplasmosis forms multiple brain abscesses especially in basal ganglia [2]. Echinococcus granulosus forms hydatid cysts in several organs involving the brain [2, 4]. Primary multiple cerebral hydatid cysts are extremely rare, often found in the middle cerebral artery territory. Typically large cysts may contain daughter cysts [4]. Fungal infections, especially in patients with immunodeficiency [5], include cerebral cryptococcosis and aspergillosis. Lowgrade astrocytomas are frequently seen in the frontal lobe and can be located in basal ganglia, oft containing cysts with smooth internal surface and transparent liquid [3]. Metastatic carcinomas are a usual cause for intracerebral cystic lesions, although having a much lower incidence of associated cysts compared to gliomas [2]. There are also neoplasm-associated benign peritumoral cysts, true arachnoid cysts [4], lacunes (usually located in basal ganglia [5]) and beneign congenital neuroglial (glioependymal) cysts, typically located within the frontal lobe [4]. To conclude, there are numerous causes of multiple intracerebral cystic lesions involving both the basal ganglia and frontal lobe white matter and have to be differentiated from DPVS. A location-based approach to intracranial cysts is helpful in establishing an appropriate differential diagnosis [4]. Lesions following a vessel territory could be due to either vascular or infectious disease [4].
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Mar 1, 2012
Tc Clifton + 1
Open Access
