Isolated Cerebral Alveolar Echinococcosis

International audienceCerebral alveolar echinococcosis (AE) is rare and mostly associated with liver involvement. We report an exceptional case of a 62-year-old man with a hereditary hemorrhagic telangiectasia harboring a primary cerebral AE mimicking neurocysticercosis with >100 cerebral lesions and without liver involvement. Human alveolar echinococcosis (AE) is a rare zoonotic infection caused by the metacestode of the fox tapeworm, Echinococcus multilocularis. Endemic regions of AE are mainly limited to the Northern Hemisphere, especially to western China, Central Europe, Alaska, Russia, and Japan [1]. The main risk factors associated with human AE are rural settings, living near a forest, mountain climate, being a farmer, and being a dog owner. Humans become accidentally infected through the ingestion of eggs shed in the feces of definite hosts (eg, foxes, dogs) [1]. Primary extrahepatic involvement of AE is rare, and cerebral involvement is unusual [1]. We report an exceptional case of primary cerebral AE in which imaging showed multiple small round contrast-enhancing lesions. We will discuss the general diagnostic approach of brain abscesses, including the differential diagnosis of multiple abscesses and the physiopathology of isolated brain involvement in this case of AE. CASE REPORT We report the case of a 62-year-old pig breeder who lived in Normandy (France) and never traveled abroad. He used to eat fruits and vegetables from his own garden. His medical history was marked by a definite diagnosis of hereditary hemorrhagic telangiectasia (HHT) visceral arteriovenous malformations (AVMs). In December 2016, he was admitted to a general hospital because of an acute headache, confusion, and gait disorders. Physical examination revealed left ptosis, ataxia, dysarthria, and mucocutaneous telangiectasia. A brain magnetic resonance image (MRI) showed multiple parenchymal small gadolini-um-enhancing lesions with hypointense signals in T1-weighted sequences, associated with a large perilesional edema in fluid attenuated inversion recovery (FLAIR) sequences (Figure 1A and E). Cerebrospinal fluid (CSF) withdrawn on day 2 revealed a lymphocytic meningitis with 230 white cells/mm 3 , a protein content of 1g/L, and normal glycorrhachia. Suspected pyogenic brain abscesses were treated by cefotaxime and metronidazole. Blood and CSF cultures were sterile, and C-reactive protein was normal. Blood samples obtained for serological testing to detect Coxiella burnetii, Rickettsia spp., Bartonella henselae, Bartonella quintana, Brucella spp., Treponema pallidum, and HIV were negative. A second-step CSF analysis was negative for mycobacteria (polymerase chain reaction [PCR] and culture), Toxoplasma gondii (PCR), Cryptococcus spp., and Nocardia spp. At day 5, the patient's neurological status deteriorated, resulting in aphasia and right hemiplegia. Thoracic and abdominal CT and abdominal ultrasound (US) were normal. Albendazole and corticosteroid were added to the treatment because of a suspected neurocysticercosis (due to both his occupation and a consistent brain imaging presentation, although this condition is extremely rare in metropolitan France) or necrotic cerebral metastasis. The patient was referred to the Infectious Diseases Unit of the University Hospital of Caen, Normandy, on day 11. As serum and CSF serology for cysticercosis were negative, cor-ticosteroid and albendazole were stopped. A first brain biopsy (day 18) only showed inflammation consistent with an extra-abscess biopsy, leading to a second brain biopsy (day 30), which showed necrotic tissue with eosinophilic material composed of fragments of a laminated layer, intensely colored by the periodic acid-Schiff (PAS) stain and Grocott's methenamine silver stain (Figure 2). No germinative layer was noted. A tapeworm was suspected, but its genus could not be identified. The results of the bacteriological analyses of the brain tissue performed by direct examination, standard culture, universal bacterial PCR targeting the 16S rRNA gene, specific culture, fungal and myco-bacterial culture, and PCR of Mycobacterium spp. were negative. An exceptional case of autochthonous neurocysticercosi