T-Cell Lymphomas in South America and Europe

Peripheral T-cell lymphomas are a group of rare neoplasms originating from clonal proliferation of mature post-thymic lymphocytes with different entities having specific biological characteristics and clinical features. As natural killer cells are closely related to T-cells, natural killer-cell lymphomas are also part of the group. The current World Health Organization classification recognizes four categories of T/natural killer-cell lymphomas with respect to their presentation: disseminated (leukemic), nodal, extranodal and cutaneous. Geographic variations in the distribution of these diseases are well documented: nodal subtypes are more frequent in Europe and North America, while extranodal forms, including natural killer-cell lymphomas, occur almost exclusively in Asia and South America. On the whole, T-cell lymphomas are more common in Asia than in western countries, usually affect adults, with a higher tendency in men, and, excluding a few subtypes, usually have an aggressive course and poor prognosis. Apart from anaplastic lymphoma kinase-positive anaplastic large cell lymphoma, that have a good outcome, other nodal and extranodal forms have a 5-year overall survival of about 30 percent. According to the principal prognostic indexes, the majority of patients are allocated to the unfavorable subset. In the past, the rarity of these diseases prevented progress in the understanding of their biology and improvements in the efficaciousness of therapy. Recently, international projects devoted to these diseases created networks promoting investigations on T-cell lymphomas. These projects are the basis of forthcoming cooperative, large scale trials to detail biologic characteristics of each sub-entity and to possibly individuate targets for new therapies.

Epstein-Barr virus-associated extranodal non-Hodgkin's lymphoma of the sinonasal tract and nasopharynx in Thailand.

Epstein-Barr virus (EBV) infection is highly associated with specific subtypes of malignant lymphoma. In our previous report on nodal malignant lymphoma in Thailand, we found that 64% of classical Hodgkin's lymphoma (cHL), 51% of non-Hodgkin's lymphoma, T-cell (NHL-T), and 13% of non-Hodgkin's lymphoma, B-cell (NHL-B) were EBV-related. In the present research, we conducted a retrospective study of primary extranodal non-Hodgkin's lymphoma of the sinonasal tract (e-NHL-ST) and primary extranodal non-Hodgkin's lymphoma of the nasopharynx (e-NHL-NP) in Southern Thailand, between 1997 and 2004. EBV-encoded RNA (EBER) expression by in situ hybridization was performed in all cases and a T-cell receptor (TCR)-g gene rearrangement study was performed in NHL-T cases. There were 18 cases of e-NHL-ST and 42 cases of e-NHL-NP detected by histologic and immunohistochemistry examinations. The percentages of e-NHL-ST and e-NHL-NP as compared to nodal malignant lymphoma were 3.7% and 6.8%, respectively. Sixteen cases (88.9%) of e-NHL-ST and 7 cases (16.7%) of e-NHL-NP were NHL-T, and the remainder were NHL-B. All of the NHL-T cases in both sites were EBER-positive. Two (5.4%) of the NHL-B cases in the nasopharynx showed EBER positive. Monoclonal bands of the TCR-gamma gene were detected in 71.4% of the extranodal NK/T-cell lymphomas, nasal type, patients; 50.0% of peripheral T-cell lymphoma, unspecified, patients; and one case of angioimmunoblastic T-cell lymphoma. This study indicates a very strong association of NHL-T in the sinonasal tract or nasopharynx with EBV infection, the link apparently being weaker in NHL-B patients. The study also indicates that most cases of extranodal NK/T-cell lymphoma, nasal type, are not the germline configuration of the TCR genes.

Characterization of angioimmunoblastic T-cell lymphomas [AILT] and its association with Epstein-Barr Virus [EBV] in Pakistani patients

To characterize angioimmunoblastic T-cell lymphoma [AILT] on morphological, immunohistochemical and molecular grounds and its association with Epstein-Barr virus [EBV] in Pakistani patients. Case series. Histopathology section of the Department of Pathology and Microbiology, The Aga Khan University Hospital, Karachi from January 01, 1992 to December 31, 2002. Over a period of 11 years archival biopsy material of 13 AILT cases [lymph nodes], identified on the basis of histological and immunohistochemical criteria, using REAL and WHO classifications, were retrieved from the files of Department of Pathology. Immunophenotyping was carried out by using CD45 [LCA], two T-cell markers CD45RO [UCHL1; monoclonal] and CD3 [polyclonal]. Polymerase chain reaction [PCR] was used to assess T-cell clonality for T-cell receptor [TCR]-b, g and immunoglobulin heavy chain [IgH] for FR2 and FR3 regions using primers recognizing conserved sequences of the variable [V], diversity [D] and joining [J] region segments. Association of EBV in AILT cases was studied by PCR and in situ hybridization [ISH]. This study showed AILT to constitute 0.71% of all NHLs [non-Hodgkin's lymphoma] [both T and B]. Immunohistochemical study revealed that the tumor cells were positive for CD45 [LCA], CD45RO [UCHL1] and CD3. All the 13 cases were largely negative for CD20 [L26], a B-cell marker, except few large scattered cells labelling. DNA extracted from all 13 lymph nodes was amplified using polymerase chain reaction [PCR]. PCR technique demonstrated clonal gene rearrangement of the TCR-b, g and IgH regions in 3 [23.1%], 7 [53.8%] and 3 [23.1%] AILT cases, respectively out of 13 cases. Association of EBV was seen in 11 out of 13 cases [84.6%] of AILT by PCR. By ISH the prevalence of EBV was detected in 8 [88.8%] out of 9 cases. The prevalence of AILT in the Pakistani population is slightly lower compared to other studies and that EBV is an etiological agent in pathogenesis of this disease

Epidemiología y patología de la leucemia/linfoma de células T del adulto en Cali y el suroccidente colombiano / Epidemiology and pathology of the adult T-cell Lymphoma in Cali and Colombian Southwest

Introducción: Este estudio se realizó con el fin de obtener un acercamiento con la epidemiología geográfica de las neoplasias linfoide en Cali y el suroccidente colombiano, con atención especial en la leucemia linfoma de células T del adulto. Materiales y métodos: Se utilizó información del Registro Poblacional de Cáncer de Cali, de las personas con linfoma no Hodgkin y leucemia linfoides entre 1987 y 1996 procedentes de la costa pacífica. Se obtuvo material incluido en parafina de los pacientes con linfoma no Hodgkin del departamento de Patología, del Hospital Universitario del Valle, con el próposito de investigar secuencias provirales para HTLV-I usando técnicas biomoleculares. Además, se obtuvieron muestras de sangre de voluntarios nativos de Tumaco que representan niveles socioecónomicos bajo, medio y alto, y se analizaron para anticuerpos contra HTLV-I/II con una prueba de imunoabsorción ligada con enzimas (ELISA, Abbott®) y confirmados por Western blot. Resultados: La tasa de incidencia global para linfoma no Hodgkin es al menos dos veces mayor para leucemias en ambos sexos y no ha mostrado cambios notables, mientras la leucemia linfoide ha aumentado en ambos sexos, de manera más notoria en mujeres. La tasa de incidencia para linfoma no Hodgkin aumenta con la edad en ambos sexos. Cinco de 75 casos de linfoma fueron positivos para secuencia de HTLV-I por PCR, en los especímenes tisulares y ninguno de los pacientes tenía prueba serológica para HTLV; 18 (5.1/100) de las 356 personas fueron positivas serológicamente para anticuerpos contra el HTLV-I muestreadas en Tumaco.Conclusiones: Varios casos de ATL pueden pasar desapercibidos en pacientes con linfoma no Hodgkin en quienes la asociación no había sido sospechada. La seroprevalencia de HTLV-I en Tumaco es más alta en mujeres. Merece la pena continuar investigando la intercurrencia con infecciones u otros factores medioambientales que facilitarían una progresión rápida de portadores ATL en habitantes del área

HTLV-I (Human T- cell lymphotropic virus), algo que decir? / HTLV-I (Human T-cell lymphotropic virus): something to say?

El virus HTLV-I se asocia a varias patologías siendo las más relevantes la paraparesia espástica y la leucemia/linfoma de células T del adulto. No tiene tratamiento específico y se han intentado varios esquemas terapéuticos para su manejo. Se revisa la literatura presentando los trabajos más actualizados en relación a la terapia.