1/2 Revista da Sociedade Brasileira de Medicina Tropical Journal of the Brazilian Society of Tropical Medicine Vol.:54:(e0641-2020): 2021 https://doi.org/10.1590/0037-8682-0641-2020 Corresponding author: Dr. Berhan Pirimoglu. e-mail: berhan.dr@gmail.com  https://orcid.org/0000-0002-1608-1189 Received 19 September 2020 Accepted 19 October 2020 Images in Infectious Diseases www.scielo.br/rsbmt I www.rsbmt.org.br Acute necrotizing encephalopathy with H1N1 virus infection in a child Berhan Pirimoglu [1] , Halil Keskin [2] and Huseyin Tan [3] [1]. Ataturk University, Medical Faculty, Department of Radiology, Erzurum, Turkey. [2]. Ataturk University, Medical Faculty, Department of Pediatric Intensive Care Unit, Erzurum, Turkey. [3]. Ataturk University, Medical Faculty, Department of Pediatric Neurology, Erzurum, Turkey. FIGURE 1: (A) Axial T2-weighted image and (B) axial FLAIR image show the symmetrical hyperintense expansile lesions in the bilateral thalami and external capsules (black asterisks). (C) Axial b-1000 image (black asterisk) and (D) axial ADC difusion image (white asterisk) show the symmetrical difusion restriction in the bilateral thalami and external capsules. A 7-year-old man presented to our radiology unit with high fever, generalized tonic-clonic type seizures, and neurological deterioration requiring intensive care. Cerebrospinal fuid analysis showed increased protein (94 mg/dL) and normal glucose (41 mg/ dL) levels. An initial brain magnetic resonance imaging (MRI) revealed symmetrical and expansile hyperintense lesions in the bilateral thalami and external capsules (Figure 1A and 1B). Restricted difusion patterns of the involved brain regions were detected (Figure 1C and 1D). These radiological imaging fndings suggested acute viral encephalitis, compatible with acute necrotizing encephalopathy (ANEC). Real-time polymerase chain reaction test performed with samples from nasopharyngeal swabs was positive for infuenza A virus (H1N1). Therefore, ANEC-associated H1N1 virus infection was diagnosed. The patient underwent antiviral, anticonvulsant, and anti-infammatory therapy. Fifteen days after therapy, a follow-up brain MRI revealed a decrease in signal intensity in the extent of lesions involving the bilateral thalami and external capsules with decreases in diffusion restriction patterns (Figure 2). ANEC is an unusual type of encephalopathy characterized by multiple bilateral brain lesions, involving the thalami, putamina, internal and external capsules, cerebellar white matter, and brainstem. It usually develops secondary to viral infections, including infuenza virus A and B, parainfuenza, varicella, and