Influenza-Associated Acute Necrotizing Encephalopathy in Siblings

Encephalopathy is an important complication associated with influenza, most frequently observed in young children, with a wide range of severity. The most severe category of influenza-associated encephalopathy (IAE) is acute necrotizing encephalopathy (ANE), characterized by high frequency of neurologic sequelae and fatal outcomes. We report two young siblings who developed fever and seizures with altered mental status. Influenza A(H1N1)pdm09 virus infection was identified in upper respiratory tract specimens from both patients, and neuroimaging revealed bilateral inflammatory lesions, consistent with acute necrotizing encephalopathy. Neither child had received influenza vaccination. Both children progressed to critical illness and required invasive mechanical ventilation. In addition to critical care management, both patients received high-dose corticosteroids, mannitol, anticonvulsants, and antiviral treatment of influenza. The older child recovered fully and was discharged 2 weeks after illness onset, but the younger sibling developed severe brainstem edema and cerebellar tonsillar herniation, and died on illness day 11. Both children tested positive for Ran Binding Protein 2 (RANBP2) gene mutations. RANBP2 is a genetic polymorphism associated with recurrent episodes of necrotizing encephalitis with respiratory viral infections. Annual influenza vaccination is especially important for ANE survivors, with or without RANBP2 mutations, their household contacts, and caregivers. During influenza season, close monitoring of any child with a history of neurological complications associated with respiratory illness is indicated, with prompt initiation of antiviral treatment with onset of acute respiratory illness, and influenza testing performed by molecular assay.

Inflammatory myofibroblastic tumor with RANBP2 and ALK gene rearrangement with bland cytological features mimicking desmoid-type fibromatosis: A case report and review of the literature

Here, we present an uncommon case of inflammatory myofibroblastic tumor (IMT) involving the mesentery. The tumor was composed of loosely arranged round-to-spindle-shaped tumor cells with amphophilic cytoplasm in an inflammatory and myxoid background. The mitotic activity was low (1 per 50 high-power fields) and the tumor cells lacked cellular atypism. Immunohistochemically, the tumor cells demonstrated strong nuclear membranous staining with anaplastic lymphoma kinase (ALK). In situ hybridization for ALK gene rearrangement revealed a splitting apart of the two signals within the tumor cells. Reverse transcription-polymerase chain reaction revealed that the tumor harbored a ran-binding protein 2 (RANBP2)-ALK rearrangement. IMTs are usually characterized by epithelioid-to-round cells featuring increased mitotic activity, occasionally demonstrating unusual tumor cells and more aggressive clinical behavior. To date, 23 IMTs have been reported with RANBP2 and ALK gene rearrangements. However, the present case demonstrated indolent cytological features, leading to a difficulty in differentiating it from desmoid-type fibromatosis.