A cyst with a scolex (vesicular), a ring-enhancing lesion with oedema (colloidal), a nodular enhancing lesion (granular) or a calcified dot (nodular calcified): the stage decides antiparasitic treatment; intraventricular and subarachnoid forms decide surgery.
Orient first
- Commonest cause of acquired epilepsy in endemic regions, including India.
- Stages: vesicular → colloidal vesicular → granular nodular → nodular calcified.
- A solitary ring-enhancing lesion < 2 cm with a scolex and seizures in an endemic area is typical; tuberculoma is the main differential.
Acquire the study
- FLAIR, T2, DWI, SWI, 3D CISS/FIESTA, post-gadolinium T1.
The manoeuvre
- T2 and FLAIR: cyst with an eccentric dot (scolex) — the "hole with a dot".
- Post-gadolinium T1: thin ring (colloidal) vs nodular (granular) enhancement; size in mm.
- DWI: the cyst does not restrict (abscess does).
- 3D CISS: intraventricular cysts and hydrocephalus.
- SWI: calcified granulomas.
What confirms it
- Cystic lesions with a scolex, or the evolution through stages, with serology and epidemiology.
What licenses you to exclude it
- A ring lesion > 2 cm with midline shift or a restricting centre favours abscess or tumour.
The classic misread
- Calling a thick irregular ring with a restricting centre neurocysticercosis — consider abscess or tuberculoma.