Intracranial recurrent hydatid cysts with secondary infection

Clinical History

A 12 year-old female was referred to the radiology department of FMIC with severe headache, vomiting and restlessness. She was unable to hold her head. The patient had undergone brain surgery in order to remove a brain hydatid cyst 6 months ago.

Imaging Findings

Brain CT images demonstrated multiple low attenuating fluid density thin walled mass lesions in the left parietal lobe without internal solid component. The largest measured 8.1 cm x 8 cm x 6.3 cm containing numerous small cystic masses (daughter cysts)(Fig. 1). This large cystic lesion shows wall enhancement in post IV contrast images (Fig. 2) and cause mid line structures displacement to the right side (Fig. 3). At least three more cystic lesions are seen adjacent to this large cyst with no wall enhancement (Fig. 4).

Discussion

Hydatid disease is caused by Echinococcus granulosus and multilocular, which mainly occurs in dogs and humans are considered the intermediate hosts [1, 2, 3]. The parasite is incidentally ingested through the contaminated food or beverages and finally through systemic circulation lodge at any organ of the body.The liver and lungs are the organs most commonly involved [1, 2].
Brain Hydatid cysts are relatively rare and account for 2% of cases [1, 2, 4, 5]. Cerebral cystic echinococcosis lesions are usually singular, and multiple cerebral cysts are extremely rare [1, 2]. Cysts usually occur in the supratentorial level and involves the middle cerebral artery territory [1-4].
Brain hydatid cysts are acquired in childhood and manifest during early adulthood [1, 5] and are benign slowly growing lesions [2, 3]. Small size cysts can be asymptomatic but when enlarged in size symptoms like headache, vomiting and sometimes ataxia, diplopia, hemiparesis, abducens nerve palsy, seizures and coma can occur depending on the location of involvement [1, 2, 5].
Both CT and MRI are used to diagnose intracranial cysts [1, 2, 5]. On CT, a solitary cyst usually shows a well defined low attenuating, rounded lesion containing a smooth thin wall without wall enhancement after IV contrast injection [1, 3]. Sometimes the cyst may cause extrinsic compression over the ventricular system resulting in hydrocephalus [3]. More specific signs include wall calcification, daughter cysts, and membrane detachment, but these findings rarely occur [2]. There is no perilesional oedema and ring enhancement in a hydatid cyst that differentiate it from a brain abscess or cystic neoplasm [1, 3].
On MRI, the cyst shows low signal intensity in T1WI and high signal intensity in T2WI, surrounded by oedema that can not be seen on CT [1]. The cyst wall is seen as a hypointense ring on both T1WI and T2WI sequences [5]. MRI can demonstrate better anatomic relationship of the cyst with adjacent structures which is helpful for surgical planning [2].
In the present case, the patient had a large solitary cystic lesion in the brain before surgery and was operated for the cyst. A few months later multiple cysts reoccurred in the left parietal lobe associated with many daughter cysts in the largest cyst. At least two of the cysts showed rim enhancement after IV contrast injection, which could represent secondary infection.

Differential Diagnosis List

Final Diagnosis

Intracranial recurrent hydatid cysts with secondary infection

URL:	https://www.eurorad.org/case/13297
DOI:	10.1594/EURORAD/CASE.13297
ISSN:	1563-4086