No abstract

Human herpesvirus-6 (HHV-6) encephalitis and myelitis following allogeneic hematopoietic stem cell transplantation (HSCT) is frequently life-threatening. We retrospectively evaluated the clinical significance of hyponatremia in cases of HHV-6 encephalitis/myelitis. Using an institutional database and medical records, we identified and retrospectively analyzed 16 cases of HHV-6 encephalitis and/or myelitis after allogeneic HSCT. HHV-6 encephalitis and myelitis were defined as the symptoms/signs with HHV-6-DNA in the cerebrospinal fluid. Seizure and memory disorder were defined as symptoms/signs of encephalitis, and dysesthesia and vesicorectal disorder as those of myelitis. Five patients developed encephalitis with or without myelitis, and 11 patients developed myelitis alone. Hyponatremia (median 129.1 mEq/L; range 125.9-130.1) was observed in all five patients with HHV-6 encephalitis at diagnosis, and values were significantly lower than those in patients with HHV-6 myelitis alone (median 137.6; range 134.0-142.2; P < 0.01). In three of the five patients with encephalitis, the decrease in sodium level preceded the clinical onset of encephalitis by one or two days. These results suggest that hyponatremia may be an important manifestation of HHV-6 encephalitis, but not of myelitis, and could be a useful tool for the early prediction or diagnosis of HHV-6 encephalitis.

BK polyomavirus (BKPyV) is recognized as a pathogen that causes diseases such as hemorrhagic cystitis and nephritis after allogeneic hematopoietic stem cell transplantation (HSCT) or renal transplantation. BKPyV-associated disease is thought to occur through reactivation under immunosuppression. However, the possibility of its nosocomial transmission and the clinical significance of such transmission have not been elucidated. During a 6-month period, nine adult patients (median age: 47 years) who had hematological disorders and who were treated with HSCT (n = 7) or chemotherapy (n = 2) in a single hematology department developed hemorrhagic cystitis due to BKPyV infection. The polymerase chain reaction products of BKPyV DNA obtained from each patient were sequenced. Of the nine patients, six had subtype I, 2 had subtype IV, and 1 had subtype II or III. In the alignment of sequences, four and two of the six subtype I strains were completely homologous (100%). These results strongly suggest that BKPyV has the potential to cause nosocomial infection within a medical facility, especially among recipients of HSCT. Further studies are clearly warranted to elucidate the route(s) of BKPyV transmission in order to establish optimal infection control.

Glial choristoma is considered to be a type of brain heterotopia consisting of ectopic central nervous tissue. We herein report a neonate with glial choristoma of the tongue who developed respiratory distress due to airway obstruction. A male neonate presented with respiratory distress due to a soft mass on the midline region of the dorsal tongue base at birth. He was intubated using a flexible fiberoptic nasopharyngoscope. MRI showed a well-circumscribed mass measuring 25 × 23 × 27 mm in size in the same region. A histologic examination confirmed a pathological diagnosis of glial choristoma. He underwent tracheotomy at 22 days of age, and a subtotal resection of the tumor was performed at five months of age. The clinical behavior of oral glial choristoma varies depending on the age at onset as well as the location and size of the mass. The small size of the organ and the narrow operating field hamper the surgical approach in neonates. The optimal therapeutic strategy for neonatal cases of glial choristoma should thus be determined based on the condition of each individual patient.

Immunoglobulin (Ig) G2 subclass deficiency is known to be associated with recurrent bacterial respiratory infections caused by capsulated bacteria. We encountered a case of recurrent pneumonia due to Streptococcus pneumoniae after allogeneic hematopoietic stem cell transplantation (HSCT). IgG2 subclass level was specifically low, and prophylactic Ig replacement successfully prevented subsequent infections. However, the cessation of Ig replacement resulted in subsequent pneumonia. These findings suggested that IgG2 deficiency could be a cause of recurrent pneumococcal infection after allogeneic HSCT.