Ultrastructural studies of jaw lymphomas and apoptosis.

Research on ultrastructural cytopathological changes and apoptosis that occur in jaw lymphoma were done by using electron microscopy and ground sections. The author described this tumor in 1977-1978 as a highly malignant and lethal condition affecting children between 2 and 8 years (mean age 5 years). A duration of illness between 2 and 3 weeks is common and with a general condition of severe toxicity, anemia, and high body temperature. Clinical and pathological features of 24 children with jaw lymphoma seen in the Maxillofacial Unit, Surgical Specialized Hospital, Medical city, Baghdad, are described. Thirteen males and 11 females were included, with a death rate at 91.1%. The morphological characteristics were examined by ground sections. Lymphoblastic lymphoma features were observed and apoptotic changes were seen in some of the cells. Electron microscopy showed a high number of mitotic figures and lymphoblast transformation to plasma cells with high nucleo-cytoplasmic ratio. Some cells had double nuclei and some nuclei were more convoluted. Apoptotic changes were seen in some cells; chromatin clumps aggregated near the nuclear membrane. Cytoplasmic processes and mitochondria showing degeneration and virus-like particles were seen in both nuclei and cytoplasm. The presence of a high mitotic figure with active oncogenic virus growth and reduced apoptosis is a poor prognostic feature in jaw lymphoma.

Expression of EBV encoded nuclear small non-polyadenylated RNA (EBER) molecules in 32 cases of childhood Burkitt's lymphoma from Israel.

We have analyzed paraffin sections from 32 children with histologically confirmed Burkitt's Lymphoma (BL) for the presence of EBV using in situ hybridization to detect expression of the EBV-encoded early RNAs (EBERs). EBV was present in the tumors of 11 patients (34%). Sixty nine percent of the children presented with abdominal disease, 19% had bone marrow infiltration and only one child had jaw involvement. There was no statistically significant difference between EBV positive and EBV negative children with regard to age, gender, origin, primary site at presentation, or clinical stage of disease. However, there was a trend for younger age in the children with EBV positive BL with a median age of 4, compared to 7 years in children with EBV negative BL. None of the 7 children of Ashkenazi Jewish origin had EBER positive disease. There was no difference in the treatment outcome between the EBV positive patients (estimated survival at 24 months of 82%) and EBV negative children (estimated survival rate of 71% (p=0.58)). In conclusion, although this is only a small series it seems that childhood BL in Israel has the clinical characteristics of sporadic, non-African type with 34% EBV association and a low incidence of jaw tumors. Our data suggest that Ashkenazi Jewish children with BL are less likely to have EBV positive tumors than other ethnic groups. However, more patients will need to be studied in order to assess the validity of this observation.

Latent infection with Epstein-Barr virus in odontogenic disorders: comparison among ameloblastoma, dentigerous cyst and odontogenic keratocyst.

In order to investigate the relationship between Epstein-Barr virus (EBV) latent infection and histogenesis of odontogenic disorders, in situ hybridization for EBV-encoded small RNA (EBER) was applied to the paraffin sections of ameloblastoma, dentigerous cyst, and odontogenic keratocyst. Eight cases (15%) of 53 ameloblastomas showed scattered signals for EBER in the parenchymal cells, whereas no reaction of EBER transcript was observed in the non-neoplastic cystic lesions. In the ameloblastoma, the follicular and plexiform types revealed the signals in the nuclei, but cystic, acanthomatous, granular, and basal cell types exhibited no reaction with EBER. The distribution of the signals without monoclonarity indicated that ameloblastoma cells may exclude EBV genomes or inactivate EBER-encoded genes. The results suggested that EBV participates as one of the transforming factors in the occurrence of ameloblastoma.