Burkitt's lymphoma: new insights into molecular pathogenesis.

The World Health Organisation classification reports three subcategories of Burkitt's lymphoma (BL)--endemic, non-endemic, and immunodeficiency associated--proposed to reflect the major clinical and genetic subtypes of this disease. These different types of BL have been reviewed and studied by immunohistochemistry and molecular methods. The results point out the heterogeneity of BL and suggest that AIDS related BL may have a different pathogenesis from that of classic BL.

Genetic alterations of the retinoblastoma-related gene RB2/p130 identify different pathogenetic mechanisms in and among Burkitt's lymphoma subtypes.

Alterations of cell cycle-associated genes probably contribute to the pathogenesis of Burkitt's Lymphoma (BL), in addition to c-myc translocation. Mutations disrupting the nuclear localization signal of the retinoblastoma-related gene RB2/p130 have been documented recently in BL cell lines and primary tumors. Given the importance of the RB2/p130 gene in controlling cell growth, mutations of this gene may result in uncontrolled cell proliferation. We tested the expression and genomic organization of the RB2/p130 gene in relation to the proliferative features of a series of BL samples collected from the endemic and sporadic regions, regardless of whether the samples were acquired immune deficiency syndrome (AIDS)-related. The expression of the Rb2/p130, p107, and cell proliferation-related proteins (cyclin A and B) was determined by immunohistochemistry. The structures of exons 19 through 22 of the RB2/p130 gene, encoding for the B domain and C terminus, were analyzed by polymerase chain reaction (PCR) analysis and single-strand conformation polymorphism (SSCP) technique. The direct PCR products were sequenced to identify the actual mutations. Our results suggest that BL is composed of a mixture of molecular types with distinct genetic and phenotypic patterns, probably resulting from different pathogenetic mechanisms. In endemic BL, the RB2/p130 gene is mutated in most of the cases, and the protein is restricted to the cytoplasm. In AIDS-related BL, high levels of nuclear expression of the wild-type pRb2/p130, p107, and cell proliferation-related proteins were detected. This finding is in line with the molecular mechanisms observed in virus-linked oncogenesis. Sporadic BLs were mainly characterized by the low nuclear values of the wild-type pRb2/p130 and, conversely, the high values of p107. The increased cell proliferation due to different alterations of cell growth control by Rb-related proteins may be the first step in lymphomagenesis, during which additional genetic changes, including missense mutations of c-myc, may subsequently occur.

HIV-associated malignant lymphomas in Kenya (Equatorial Africa)

The clinical and pathological features of acquired immune deficiency syndrome (AIDS)-related lymphomas, including their relationship with other viruses, such as Epstein-Barr virus (EBV) and human herpes virus-8 (HHV8), have been the subject of several studies from North America and Europe. No consistent data have been reported in Africa, where AIDS runs an epidemiological and clinical course different from that observed in Western countries. We retrospectively evaluated the presence of human immunodeficiency virus (HIV), HHV8, and EBV in 146 cases of malignant lymphomas collected in Kenya (Equatorial Africa), with the use of polymerase chain reaction (PCR) and in situ hybridization (ISH). The PCR technique confirmed HIV infection in 16 HIV-seropositive subjects (11%) and showed the presence of HIV sequences in five additional cases (3%) in which the occurrence of lymphoma was the only clinical manifestation. Our findings suggest that AIDS-related lymphomas are not pathogenetically homogenous, and different mechanisms may contribute to lymphomagenesis in these severely immunocompromised patients. In our series, no association of Hodgkin's disease (HD) with HIV infection could be shown. Among non-HIV-related lymphomas, EBV was present in 94% of Burkitt lymphoma (BL) occurring in patients younger than 15 years of age, in 87% of HD independently of age, sex, and histological types, in 60% of anaplastic large cell lymphoma (ALCL), and to a lesser extent (13%) in large B-cell lymphoma (LBCL) cases. Only one tumor, a case of HD, showed HHV8 by PCR.

Different patterns of cell proliferation and death and oncogene expression in cutaneous malignant melanoma.

Ninety-six cutaneous melanomas (CMs) were investigated aiming at finding differences, if any, among the main four clinicopathological types, for Bcl-2, c-myc and p53 protein expression, and for tumor cell proliferation and death indices. Proliferation was assessed by calculating the mitotic index (MI, number of mitoses) and the MIB1 labelling index (M-LI, number of MIB1+ nuclei), and tumor cell death by calculating the apoptotic index (AI, number of apoptoses) among 1000 tumor cells. CMs were subdivided into thin (<1 mm) and intermediate thickness (1-4 mm) tumors. Bcl-2 expression did not significantly change among different types. c-myc Expression decreased especially in thicker superficial spreading (SSM) and lentigo maligna melanoma (LMM) types. p53 Expression was higher in nodular melanoma (NM) and in acral lentiginous melanoma(ALM), which also showed the highest degrees of proliferation. AI was significantly higher in thin rather than in intermediate thickness SSMs, LMMs and ALMs (8.4 vs. 2; 6.1 vs. 2.3, and 5.8 vs. 3.6, respectively). AI was low in thin (1.7) and intermediate thickness (1.9) NMs, which also showed high MI (3.9 and 4.5, respectively), and M-LI (16.7 and 2.9, respectively). Thin and intermediate thickness ALMs also showed high MI and M-LI (4.1 vs. 5.2 and 11.3 vs. 14.6, respectively). Bcl-2 is among genes which inhibit apoptotic death, whereas c-myc and p-53 genes promote this process. In CMs, no relation was found between Bcl-2 expression, MI, PI, and AI. All SSMs, LMMs, and ALMs with a high AI showed a high c-myc expression and were negative for p53. c-myc, Although highly expressed, did not promote a significant apoptotic death in NM type. Bc12, c-myc, and p53 were not equally expressed nor equally related to tumor cell turnover in all CMs, suggesting their different influence on the various types and stages, and the role of other factors in CM growth control.

The role of Epstein-Barr virus in Hodgkin's disease from different geographical areas.

Recent studies have suggested that Epstein-Barr virus (EBV) may play a role in the aetiology of Hodgkin's disease. To determine the role of EBV in childhood Hodgkin's disease in different geographical areas, immunohistochemical staining and in situ hybridisation were used to analyse latent membrane protein 1 (LMP 1) and small nuclear non-transcribed RNAs (EBER-1) respectively. Testing for EBV within the Reed-Sternberg and Hodgkin's cells was carried out in childhood Hodgkin's disease from 10 different countries. The proportion of LMP 1 positive cases varied significantly, being 50% of cases from the United Kingdom (38/75), South Africa (9/18), Egypt (7/14), and Jordan (8/16), 60% from the United Arab Emirates (6/10), 70% from Australia (11/16), 81% from Costa Rica (34/42), 88% from Iran (7/8), 90% from Greece (20/22), and 100% of the 56 cases from Kenya. A sensitive polymerase chain reaction based EBV strain typing technique was established using archival tissues. EBV strain type 1 was shown to be predominant in childhood Hodgkin's disease from the United Kingdom, South Africa, Australia, and Greece. Type 2 was predominant in Egypt. EBV strain types 1 and 2 were both detected in some cases of childhood Hodgkin's disease in the United Kingdom, Costa Rica, and Kenya. The high incidence of EBV and the presence especially in developing countries of dual infection with both strain types 1 and 2 may reflect socioeconomic conditions leading to malnutrition induced immunological impairment. The possibility of HIV infection also needs to be explored.

Concurrence of high levels of interferons alpha and beta in cord and maternal blood and simultaneous presence of interferon in trophoblast in an African population.

A high concentration of interferon-alpha (IFN-alpha) (> 5 U/ml) in cord blood was used as the criterion for establishing our study group. In a collection from deliveries by 269 Kenyan women, 16 such cord samples with matching maternal blood and placental biopsies were identified. These 16 were studied in detail together with 23 randomly selected among those with low cord IFN-alpha levels. The levels of IFN- in retal blood correlated with levels in their mothers for both IFN-alpha and beta but not for IFN-gamma. IFN-alpha was furthermore demonstrated in villous and decidual trophoblast from 15 (94%) placentae from donors with high IFN-alpha in the cord blood but not in the placenta of any low IFN level donors. In contrast, IFN-beta was not demonstrated in any placenta. These observations suggest simultaneous IFN induction in the three compartments, transplacental IFN transport, or trophoblast production of IFN to both circulations. Looking for IFN inducers, we did serologic tests for nonspecific indicators of inflammation and for specific virus and protozoan infections, but these showed no relation to elevated IFN levels. Immunohistology also revealed no evidence of a number of placental infections. The cause of the high levels of IFN-alpha could still be infectious but remains unexplained and may be noninfectious.

Smoking and reproductive health: cigarette smoking as a risk factor in ectopic pregnancy.

To evaluate the association between ectopic pregnancy (EP) and smoking, a hospital based case-control study was undertaken. Also studied were other potential risk factors namely: PID, undernutrition, blood group 'O', the use of IUD, prior abnormal pregnancies and prior abdominal surgery. The investigation included 72 cases diagnosed at the University of Health Sciences, Kansas City, Missouri from January 1, 1976 through December 31, 1987 and 72 pair-matched controls selected from live-birth deliveries at the same hospital. Univariable McNemar analyses revealed four strong risk factors: having ever smoked (OR = 2.1, p = 0.04), previous EP (OR = 14.3, p = 0.0001), previous fetal loss (OR = 4, p = 0.04) and previous pelvic and abdominal surgery (OR = 6.3 p = 0.0001). A stepwise logistic regression analysis using parity, eversmoking, underweight and PID was performed. Only PID remained strongly associated with EP after the first step (p = 0.009).

Pregnancy outcome and placental weights: their relationship to HIV-1 infection.

The relationship between placental characteristics, including weight and inflammation, and pregnancy outcome was examined as part of a case control study looking into the impact of maternal HIV-1 infection on pregnancy outcome. Cases defined as low birth weight (< 2500g) or stillbirth deliveries, were compared to controls defined as mothers who delivered a live born neonate weighing 2500g or more. The mean placental weight and the mean foetal/placental weight ratio were significantly lower in cases (n = 253) than in controls (n = 216) (p < .05). Placental inflammation (chorioamnionitis) was significantly associated with prematurity (p < .001) and with stillbirth (p < .05), maternal HIV-1 antibody being a risk factor for chorioamnionitis in the preterm group. These data support a correlation between placental weight and pregnancy outcome, and suggest that maternal HIV-1 infection is a risk factor for chorioamnionitis in HIV-1 seropositive preterm deliveries.

PIP: In 1988, researchers compared data on 796 low birth weight (LBW) (500-2500 gm) infants and stillborns (cases) with data on 71 live-born infants weighing more than 2500 gm (controls) to examine the effect maternal HIV-1 infection has on the association between maternal placental characteristics and pregnancy outcome. 3.1% of control mothers of preterm infants, 7.7% in infants small for gestational age (SGA), and 11.7% for mothers of stillborns were HIV-1 seropositive. HIV-1 antibody status was linked independently with preterm birth (odds ratio [OR] = 2.1), SGA infants (OR = 2.3), and fetal death (OR = 2.7). the mean and standard deviation of gestational age and fetal and placental weight and the fetal/placental weight (F/P) ratio were much lower in LBW infants and stillborns (p .001). Mean placental weight in SGA infants born to HIV-1 seropositive mothers was significantly higher than that of SGA infants born to HIV-1 negative controls (487 gm vs. 443 gm; p .05), resulting in a lower F/P ratio among SGA infants of HIV-1 seropositive mothers (4.8 vs. 5.2; p .05). Moderate to severe chorioamnionitis, villitis, and funisitis (all signs of placental inflammation) were associated with prematurity (p .001) and stillbirths (p .05). HIV-1 infection was strongly linked to moderate to severe chorioamnionitis (31% vs. 14%; p .05; OR = 6.1). among preterm infants. These findings strengthen the belief that cumulative immunosuppressive effects of HIV-1 infection and pregnancy assist increasing infection, resulting in chorioamnionitis and possible subsequent prematurity or stillbirth.

Cervical cancer screening and detection of genital HPV-infection and chlamydial infection by PCR in different groups of Kenyan women.

A pilot study was conducted in Nairobi, Kenya, to evaluate the feasibility of a larger study on the prevalence of cervical cancer and precancerous lesions and on the role of Sexually Transmitted Diseases (STD) as risk factors for cervical cancer in Kenya. 692 women were screened for cervical cancer by cytology in 3 City Commission family planning clinics and in 1 City Commission STD referral clinic in Nairobi. In one family planning clinic and in the STD clinic, a sample of the participating women (n = 212) was also screened for genital Human Papillomavirus (HPV) and chlamydial infection by Polymerase Chain Reaction (PCR). Of all women screened for cancer, 5.1% had a PAP smear showing mild dysplasia, 1.2% moderate dysplasia and 0.15% severe dysplasia or worse. Of the women screened for genital HPV infection and for chlamydial infection, the following results can be reported: in women attending the family planning clinic, HPV-DNA was detected in 3.7% (0.9% HPV6/11 and 2.8% HPV 16/18/31/33) and Chlamydia trachomatis in 6.4%; in women attending the STD clinic, HPV-DNA was detected in 16.5% (1% HPV6/11 and 2.8% HPV 16/18/31/33) and Chlamydia trachomatis in 4%. A significantly higher frequency of HPV-infection was observed in the STD clinic, while this was not the case for chlamydial infection.

Human papilloma virus infection in dysplastic cervical smears based on the presence of koilocytes: a study of 280 cases.

In order to estimate the frequency of Human Papilloma Virus (HPV) infection among patients and women attending the Family Planning Clinics and having dysplastic cervical epithelium, a retrospective examination of cytology slides was undertaken at Kenyatta National Hospital's (KNH) Cytology Laboratory. All slides with a diagnosis of slight dysplasia or greater were re-evaluated by the author. Only slides received between 1st January 1983 and 31st December 1987 were included. Observation of koilocytosis in at least one cell was taken to represent HPV infection. A total of 280 cases met the inclusion criteria during the said period. 78 (20%) of these showed evidence of HPV infection. Examination of Papanicolaustained cytology slides for the presence of koilocytes is not the most accurate method of detecting HPV infection but it does demonstrate that the prevalence of koilocytes is higher in dysplastic cervical epithelium than in the general population which is estimated to be about one per cent. HPV is generally believed to be a significant aetiologic agent in the development of cervical cancer in Kenya and should be under surveillance through cytology smear examination.

Clear cell sarcoma of tendons and aponeuroses: histogenesis and mode of treatment.

Clear cell sarcoma of tendons and aponeuroses is a rare, slow-growing malignant tumor arising from the tendons and aponeuroses of the lower extremity, more often in the foot. Although it appears to be a benign tumor, the clear cell sarcoma can be a malignant sarcoma capable of local recurrences or distant metastases. Microscopically, there is a rather distinctive picture characterized by discrete nests and fascicles composed of spindle cells, and a small round-to-ovoid nucleus containing a central prominent basophilic nucleolus. Since there is some controversy over the best way to treat this disease, and since its histogenesis is still unknown, the authors elected to report the case of a 28-year-old white male for three reasons: first, to illustrate that the tumor is of neural crest derivation; second, to show that an ultrastructural evaluation of the tumor is imperative in some cases; and lastly, to suggest that amputation is the treatment of choice in localized disease.

Microcystic adenoma of the pancreas with myoepithelial cells. A hitherto undescribed morphologic feature.

A case of microcystic adenoma (glycogen-rich cystadenoma) of the exocrine pancreas in a 62-year-old white female presenting with adult-onset diabetes mellitus is reported. Clinical, histopathologic, and ultrastructural findings are discussed with particular emphasis on the presence of myoepithelial cells, a morphologic feature not seen in this tumor previously. The controversy over diabetes mellitus as a significant related factor is also discussed.