After surgery, when examining minutely medical history in detail, the patient reported a history of exposure to schistosome-infected water. Then, the patient was treated with praziquantel (20mg/kg per day) for 6 days with concurrent administration of dexamethasone. The patient was followed up 5 months later with complete resolution of the symptoms, companying with the complete disappearance of lesion on MR images.
Schistosomiasis is one of the most widespread parasitic infections, which is caused by blood flukes of the genus schistosoma. Worldwide, about 200 million people are infected with schistosomes (1, 7). Three major schistosome species are Schistosoma haematobium (endemic in Africa and the eastern Mediterranean), Schistosoma mansoni (endemic in Africa, the Middle East, the Caribbean, and South America), and Schistosoma japonicum (endemic mainly in China, Japan, and the Philippines) (3). Although digestive system involvement appears to be a common manifestation of schistosomiasis, brain involvement is exactly rare. In addition, isolated intracranial schistosomiasis without hepatosplenomegaly is even rare.
The diagnosis for isolated cerebral schistosomiasis may be quite challenging. The clinical manifestations are non-specific, and laboratory findings such as eosinophilia and the evidence of schistosome ova in urine or stool may not be present. Neuroimaging examination usually shows a non-specific tumoral form. MRI imaging usually reveals a heterogeneous enhancement mass with surrounding edema, with a central linear enhancement surrounded by multiple enhancing punctuate nodules, forming an "arborized" appearance on T1-weighted images (8). The cerebral cortex and leptomeninges are the most frequent sites involved, whereas the white matter, hippocampus, thalamus, basal ganglia, cerebellum, midbrain, and choroid plexus are less common. Pathological examination may provide accurate diagnosis with the evidence of granulomatous response to schistosome eggs (4). Stereotaxic biopsy can be considered to determine the diagnosis definitively, and then following medical therapy seems to provide a suitable outcome in most cases (2, 5). In this case, the patient's history of non-specific clinical manifestation, laboratory tests, abdominal ultrasonography, and MRI examination was misleading and led to the initial diagnosis of glioma. Following the pathologic diagnosis, abdominal CT was taken and showed no schistosomiasis involvement in other organs.
For treatment, praziquantel is proven favorable against all species of schistosomes (9). For schistosomiasis japonica, cure rate attains 70% to 90%. Those who are not cured may also benefit because the egg counts fall to one fifth or less of pretreatment levels. In addition, corticosteroid administration is also beneficial. Nowadays, the indications of operation are still controversial. In our opinion, operation is necessary under the following conditions: (i) MRI scanning indicates intracranial mass effect with severe edema; (ii) praziquantel has no effect to control intracranial hypertension; (iii) glioma or other malignancies could not be excluded before surgery; and (iv) recurrent and intractable epilepsy (4). Our patient underwent surgical resection followed by standard therapy for schistosomiasis. In this case, the patient made a good recovery and his initial symptom of headache disappeared after operation and medicine treatment without new complaints.
Contributed by Zhe Bao Wu, Yi Jun Cheng, Wei Guo Zhao