Human Herpesvirus-6 Encephalitis After Hematopoietic Stem Cell Transplantation

© 2014 Harborside Press® CASE STUDY Mrs. L. was in good health until she was diagnosed with acute myeloid leukemia (AML) at the age of 63. She had presented to her primary care provider with a productive cough and was found to have pancytopenia, with 16% myeloid blasts on a peripheral blood draw. She was admitted to a major metropolitan hospital for treatment of suspected AML. A bone marrow biopsy was performed, resulting in 44% myeloid blasts with complex cytogenetic studies [46,XX,der(16)t(1;16)(q21;q24)[2]/46,idem,t(4;16) (p12;q24)] and background ringed sideroblasts and dyserythropoiesis, implying underlying myelodysplasia in addition to AML. Molecular testing for FLT3, NPM1, and CEBPA was not performed, given the picture of antecedent myelodysplastic syndrome (MDS). The French-American-British classification system traditionally used for AML cases is no longer applicable for MDS in light of the system revisions in 2008. Mrs. L. began standard 7+3 induction chemotherapy with daunorubicin and cytarabine (Table 1). Her bone marrow biopsy on day 14 was negative for residual AML, and her course was complicated only by tenosynovitis of the left foot, chemotherapy-induced nausea and vomiting, and culture-negative neutropenic fevers. Her posttreatment bone marrow biopsy was negative for AML but showed some residual dysplastic changes consistent with MDS; therefore, she received 5+2 consolidation chemotherapy with daunorubicin and cytarabine (Table 1). Following this regimen, Mrs. L. was rehospitalized for neutropenic fever. She developed sepsis from Streptococcus oralis, requiring intensive care for hypotension but no intubation. She completed a course of IV cefepime, recovered, and was discharged home. Due to the continued dysplasia in her bone marrow and the high risk for recurrence of AML, even after consolidative chemotherapy, Mrs. L. was referred for allogeneic hematopoietic stem cell transplant (HSCT), with the intent of a cure. Due to her age, she was found to be an acceptable