A Case of Malignant Melanoma Arising in Mediastinal Malignant Teratoma.

We report about a 14-year-old boy who presented with an anterior mediastinal mass that was diagnosed as malignant teratoma. Surgical resection was performed along with pre- and postoperative chemotherapy. Although elevated alpha-fetoprotein became negative, he experienced pain in his right hip joint 3 months after resection. Systematic evaluation revealed multiple locations of metastasis, and the pathological diagnosis based on bone biopsy was malignant melanoma originating from malignant teratoma, which rapidly progressed. He died 15 months after diagnosis of the original malignant teratoma. Diagnosing and treating malignant transformation of teratoma, including malignant melanoma, is difficult because it is very rare. To our knowledge, this is the second reported case of malignant melanoma arising from a mediastinum malignant teratoma, with both cases having a poor prognosis. In addition to the follow-up of tumor markers, systematic evaluation, including imaging, should be considered even after remission to monitor malignant transformation of teratoma. We expect to establish a successful therapy and improve mortality rate after more such cases are accumulated.

[Monitoring of Epstein-Barr virus-infected cells by flow cytometer permits early diagnosis and evaluation of disease progression in EBV-associated hemophagocytic lymphohistiocytosis].

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is characterized by clonal expansion of EBV-infected CD8(+)T-cells. We have recently demonstrated that detection of a clonally expanded population of EBV-infected CD8(+)T-cells with CD5 down-regulation was a useful tool to distinguish EBV-HLH from EBV-related disorders such as severe infectious mononucleosis. A 5-year-old girl who presented with fever, pancytopenia and liver dysfunction was diagnosed by this method in addition to conventional diagnostic tests. Further, EBV-infected cells were identified as CD5(-)HLA-DR(+) TCR V ß3(+) CD8(+)T cells, an increase or decrease of which over time reflected the disease severity in this patient. Treatment of patients with EBV-HLH varies from steroid alone to intensive chemotherapy or hematopoietic stem cell transplantation. Easy monitoring of EBV-infected cells by using flow cytometry over time may provide useful information to choose an appropriate treatment for each individual patient with EBV-HLH.

Enhanced exon 2 skipping caused by c.910G>A variant and alternative splicing of MEFV genes in two independent cases of familial Mediterranean fever.

Most reported cases of familial Mediterranean fever (FMF) involve missense mutations of MEFV concentrated within exon 10. We experienced two independent pedigrees of a unique variant in the MEFV gene that might cause excessive exon 2 skipping due to enhanced alternative splicing. In this study, we tried to elucidate the molecular mechanism of the MEFV variant as a cause of the FMF phenotype. Peripheral blood was obtained from volunteers and two patients with homozygous c.910G>A variant of the MEFV gene. MEFV messenger RNA (mRNA) expression patterns in mononuclear cells and granulocytes were compared using forward and reverse primers from exons 1 and 3, respectively. Expression profiles of pyrin were examined by transfecting wild-type and variant MEFV genes into HEK293T cells. Expression of normal-sized mRNA was extremely reduced in these patients, whereas that of aberrant short mRNA, deleting exon 2 (Δex2), was significantly increased. Immunohistochemical and immunoblotting analyses revealed a truncated immunoreactive pyrin protein in cells transfected with Δex2 cDNA. The MEFV gene c.910G>A variant results in accelerated aberrant splicing with abnormal protein size, presumably leading to anomalous pyrin function. This is the first report to show that an MEFV variant other than missense mutation is responsible for the FMF phenotype.

Clinical significance of cloned expansion and CD5 down-regulation in Epstein-Barr Virus (EBV)-infected CD8+ T lymphocytes in EBV-associated hemophagocytic lymphohistiocytosis.

Epstein-Barr virus (EBV) is the pathogen that most commonly triggers infection-associated hemophagocytic lymphohistiocytosis (HLH) and ectopically infects CD8(+) T cells in EBV-associated HLH (EBV-HLH). We recently described an EBV-HLH patient who had a clonally expanded population of EBV-infected CD8(+) T cells with CD5 down-regulation. To determine whether this finding could serve as a useful marker for EBV-HLH, we investigated 5 additional patients. We found a significant increase in the subpopulation of CD8(+) T cells with CD5 down-regulation and bright human leukocyte antigen (HLA)-DR expression in all patients with EBV-HLH but not in patients with infectious mononucleosis or in control subjects. Such T cells were frequently found to be larger cells that stained positive for a specific T cell receptor VB. We also demonstrated that those cells were the major cellular target of EBV, and their numbers progressively declined in parallel with the serum ferritin levels. All together, our findings reveal the immunophenotypic characteristics of EBV-infected CD8(+) T cells and may provide a valuable tool for the diagnosis of EBV-HLH.

Flow cytometric analysis of skin blister fluid induced by mosquito bites in a patient with chronic active Epstein-Barr virus infection.

In chronic active Epstein-Barr virus (EBV) infection (CAEBV), ectopic EBV infection has been described in T or natural killer (NK) cells. NK cell-type infection (NK-CAEBV) is characterized by large granular lymphocytosis, high IgE levels and unusual reactions to mosquito bites, including severe local skin reactions, fever and liver dysfunction. However, the mechanisms underlying these reactions remain undetermined. Herein, we describe a patient with NK-CAEBV whose blister fluid after mosquito bites was analyzed. The patient exhibited significant increases in the percentage of CD56(+) NK cells in the fluid compared with a simple mosquito allergy, in which the majority of infiltrated cells were CD203c(+) cells, indicating basophils and/or mast cells. His fluid also contained CD203c(+) cells, and his circulating basophils were activated by mosquito extracts in vitro. These results suggest that CD203c(+) cells as well as NK cells may play pathogenic roles in the severe skin reactions to mosquito bites in NK-CAEBV.

Skin infiltration of CD56(bright) CD16(-) natural killer cells in a case of X-SCID with Omenn syndrome-like manifestations.

We observed a patient with X-linked severe combined immunodeficiency (X-SCID) with Omenn syndrome-like manifestations. X-linked inheritance, absence of CD132 expression and impaired response to interleukin-2 (IL-2) indicated that the case is typical of X-SCID due to gamma(c) defect. However, this case was unusual in that circulating natural killer (NK) cells were increased and nearly half of these NK cells exhibited the CD56(bright) CD16(-) phenotype. A missense mutation was found within exon 5 of the IL2RG gene. The identical mutation was detected within NK, CD4(+) T and B cells. Engraftment of maternally derived NK cells or gene reversion was ruled out. The erythroderma-like skin lesion was characterized by infiltration of the dermis by CD56(bright) NK cells admixed with CD1a(+) dendritic cells (DC). Expression of mRNA for inflammatory cytokines was significantly enhanced within the skin. This may be the first human case to demonstrate that close cell-to-cell contact between DC and NK cells provides an effective alternative pathway for NK cell differentiation/activation in vivo.

Immunophenotypic analysis of Epstein-Barr virus (EBV)-infected CD8(+) T cells in a patient with EBV-associated hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a severe and often fatal condition characterized by uncontrolled activation of T cells and macrophages. In Epstein-Barr virus (EBV)-associated HLH (EBV-HLH), the pathogenic roles of ectopic EBV infection in the T-cell population and of clonal proliferation of EBV-infected T cells has been described. However, the immunophenotype of EBV-infected T cells has not been fully characterized. Here we describe a case of EBV-HLH presenting with a massive clonal proliferation of CD8(+) T cells with TCR VB14. Analysis of in situ hybridization for EBV-encoded small RNA1 showed that only CD8(+) T cells harbored EBV in this patient. The EBV-infected TCR VB14(+) CD8(+) T cells exhibited unique immunophenotypic features including lacked CD5 expression and a markedly bright expression of HLA-DR. After initiation of treatment with prednisolone, etoposide, and cyclosporin A, the percentage of infected cells declined progressively in parallel with other serum markers such as ferritin. These findings suggest that lacking expression of CD5 on CD8(+) T cells with specific TCR VB may serve as a useful marker of dysregulated T-cell activation and proliferation in EBV-HLH.

Reactive peripheral blood plasmacytosis in a patient with acute hepatitis A.

Reactive plasmacytosis is a transient expansion of plasma cell progenitors and precursors. This rare condition has been reported to occur mainly in infections and tumors. We describe a case of acute hepatitis A presenting with marked peripheral blood plasmacytosis. Plasma cells made up 27.5% of the mononuclear cells and had the immunophenotype CD10-CD19+CD20-CD21-CD23-CD34-CD38++HLA-DR+. Although the level of interleukin 6 was not increased, the presence of activated T-cells with an inverted CD4/CD8 ratio and high levels of soluble interleukin 2 receptor and neopterin indicated a marked immune response to acute hepatitis A. The patient's plasma cells had almost disappeared from the blood by hospital day 16. This report may represent the first described case of reactive peripheral blood plasmacytosis in acute hepatitis A.

Somatic revertant mosaicism in a patient with leukocyte adhesion deficiency type 1.

Leukocyte adhesion deficiency type 1 (LAD-1) is an autosomal recessive disorder caused by mutations in the ITGB2 (CD18) gene and characterized by recurrent severe infections, impaired pus formation, and defective wound healing. We describe an unusual case of severe phenotypic LAD-1 presenting with somatic mosaicism. The patient is a compound heterozygote bearing 2 different frameshift mutations that abrogate protein expression. However, CD18 expression was detected in a small proportion of T cells but was undetectable in granulocytes, monocytes, B cells, and natural killer (NK) cells. The T cells were not of maternal origin, lacked the paternal mutation, and showed a selective advantage in vivo. Molecular analysis using sorted CD18+ cells revealed them to be derived from a single CD8+ T cell carrying T-cell receptor VB22. These findings suggest that spontaneous in vivo reversion was responsible for the somatic mosaicism in our patient.