Since 15-20 days, a 40-year-old man is unable to look properly upwards. On CT scan study, a cystic lesion within the inferior oblique muscle with probable mural eccentric 'dot' is noted. The most-likely diagnosis is
Neurocysticercosis: It occurs at gray-white matter interface of brain most commonly.In neurocysticercosis on imaging studies, findings vary with stage, from nonenhancing cyst (CSF density) with mural nodule (vesicular stage) to cyst wall enhancement in form of ring like enhancement (colloidal vesicular stage) to an isodense cyst with a hyperdense calcified scolex with surrounding perilesional edema and enhancement of contrast still persisting (granular nodular stage) to a small calcified nodule without mass effect or enhancement in the last stage (nodular calcified stage).Hematogenous spread to ocular tissues, paicularly extraocular muscles of eye, may occur in cysticercosis presenting with above said features on CT scan. Intraventricular location (racemose type) is rare. Most lymphangiomas appear homogeneously cystic on CT. Ocular Toxocara canis infection causing larval granulomatosis and leading to chronic endophthalmitis and retinal detachment is a well-defined cause of unilateral leukokoria in children. The CT scan usually reveals a diffuse, nonenhancing, well-defined hyperdense lesion occupying most of the globe. Ocular dermoid os usually extraconal, non-enhancing mass with smooth margins,cystic and/or solid components,which are demonstrated on imaging by fat, fluid or soft tissue signal;occasionally calcifications.
Ocular dermoid
Ocular cysticercosis
Toxocara infection
Ocular lymphangioma
Neuroradiology