INTRODUCTION Granulomatous inflammation is a distinctive ...

Diagnosis is primarily made by imaging studies. In the case of E. granulosus, CT or MRI scans of
brain typically demonstrate a spherical cystic lesion with smooth borders (Figure 15, 16) (Tuzun
et al., 2002). When the internal images from the protoscolexes "hydatid sand" are seen, the image
can be diagnostic. Midline shift and distortion of the ventricles are common. Lesions are usually
not inflamed and thus do not have surrounding edema or enhancement. The cyst wall usually
shows a rim of low signal intensity on both TI- and T2-weighted images. T2-weighted images are
better than TI-weighted images in revealing the wall of the hydatid cyst because the low-signalintensity
cystic wall contrasts well with the high-signal-intensity fluid content Cysts may be found
outside the CNS, which suggests that the CNS lesion is also due to hydatid disease (Haliloglu et al.,
1997). The CT appearance of E. multilocularis is less distinct. It may present as an ill-defined mass
lesion and most cases will also have evidence of liver involvement (David et al., 2004).
Figure 15. Hydatid. Axial contrast enhanced T1 weighted
image reveals round well-circumscribed hypointense cyst.
NoteMarked shift of midline structures to left. No contrast
enhancement is seen. (Meric and Baki, 1998)
Figure 16. Hydatid. Axial contrast enhanced T1
weighted image reveals multiple cerebral cysts.
Note shift of midline structures to left.. (Meric and
Baki, 1998)
In doubtful cases, serologic assays can be diagnostic. Enzyme-linked immunosorbent assay
(ELISA) or indirect hemagglutination assays are readily available and can be confirmed by
immuno blot assays. However, the sensitivity is not optimal for extrahepatic disease. For E.
multilocularis, the EM2 ELISA with purified antigen is the confirmation test (David et al., 2004).