HHV6 Encephalitis Complicating Post Stem Cell Transplantation Course: A Case Series of Five Leukemic Patients (P4.315)

Objective: To report clinical, radiological and EEG features of HHV6 encephalitis occurring in leukemic patients who underwent stem cell/bone marrow transplantation. Background: Literature about HHV6 encephalitis in leukemic patients post stem cell/bone marrow transplantation is limited and consists mainly of a few case reports. We present a case series of five patients seen in MD Anderson Cancer Center. Design/Methods: Retrospective review of five leukemic patients with HHV6 encephalitis complicating their post-transplant courses. Subjects included three patients with CML, one patient with CLL and one with ALL. Results: The study patients developed altered mental status within a few months after transplantation; two of whom in overt coma. Other clinical features included seizures, headache, fever and extrapyramidal features. Four required ICU admission with intubation. Comorbidities included: pancytopenia, sepsis, graft versus host disease, and multi-organ failure. MRI brain showed T2/FLAIR hyperintensities in four patients: two in bilateral temporal lobes with corresponding diffusion restriction, one in the thalamus/hypothalamus/brainstem/cerebellum/basal ganglia and one in the periventricular areas. EEG showed focal electrographic seizures coming from temporal lobes in two patients, periodic epileptiform complexes in three patients, focal slowing in two patients, and diffuse slowing in three patients. Spinal fluid showed pleocytosis, high protein and positive HHV6 PCR. Foscarnet was used as anti-viral agent for all patients. Anti-epileptics used included phenytoin, levetiracetam and valproic acid. Four patients died within few months; one patient had a complete recovery. Conclusions: HHV6 encephalitis can add significant morbidity and mortality to leukemic patients who have undergone transplantation. Salient EEG characteristics include periodic epileptiform complexes and overt temporal lobe seizures. MRI findings were T2/FLAIR signal hyperintensities primarily in the temporal lobes. We suggest that leukemic patients with altered mental status following transplant should empirically be started on Foscarnet along with indicated antiepileptic agents until spinal fluid viral studies are obtained. Disclosure: Dr. Yassin has nothing to disclose. Dr. Tummala has nothing to disclose.