<prompt> Which of the following statements on lymphoma is not True -A single classification system for Hodgkins disease HD is almost universally acceptedHD more often tends to remain localized to a single group of lymph nodes and spreads by contiguitySeveral types of non Hodgkins lymphoma NHL may have a leukemic phaseIn general follicular nodularNHL has worse prognosis compared to diffuse NHL  <response>: One of the confusing aspects of the lymphoid neoplasms concern the use of descriptive terms Lymphocytic leukaemia and LymphomaLeukemia is used for lymphoid neoplasms presenting with widespread involvement of the bone marrow usually accompanied by the presence of a large number of tumor cells in the peripheral blood.Lymphoma, on the other hand, is used to describe proliferations arising as discrete tissue masses.Traditionally these terms were attached to what were felt to be distinct entities.However, the line between lymphocytic leukaemias and the lymphomas often blurs.Many types of lymphoma occasionally present with a leukemic peripheral blood picture accompanied by extensive marrow involvement and evolution to leukemia is not unusual during progression of incurable lymphoma. Conversely, tumors identical to leukaemias sometimes arise as soft tissue masses without evidence of bone marrow disease.Hence when applied to particular neoplasms, the terms leukaemia and lymphoma merely describe the usual tissue distribution of the disease at the time of clinical presentation.Historically few areas of pathology have evoked as much controversy and confusion as the classification of NHL and related lymphoid neoplasms. In some older classification schemes, more than two dozen types of B-cell lymphomas were listed - a nomenclature system that was mind-numbing challenge for students and pathologists. This chaotic situation has improved greatly during the last decade.In 1994, a group of hematopathologists, oncologists and molecular biologists came together to create the revised European-American classification of lymphoid neoplasms. REALThis classification incorporated objective criteria such as immunophenotype, and genetic aberrations together with morphologic and clinical features to define distinct clinicopathologic entities.Experience shows that most entities in the REAL classification can be diagnosed reproducibly by experienced pathologists and stratify patients into good and bad prognostic group.More recently an international group of hematopathologist and oncologists convened by the World Health Organization WHO reviewed and updated the REAL classification, resulting in the inclusion of a number of additional rare entitiesPresented here is the WHO classification, which sorts the lymphoid neoplasm into five broad categories based on their cell of origin :Precursor B-cell neoplasm neoplasm of immature B cellsPeripheral B-cell neoplasm neoplasm of mature B cellsPrecursor T cell neoplasm neoplasm of immature T cellsPeripheral T cell and Nk cell neoplasms neoplasm of mature T cells and natural killer cellsHodgkins lymphoma neoplasm of Reed-Sternberg cell and variantWithin the broad group of lymphomas, Hodgkin lymphoma is segregated from all other forms, which constitute the Non Hodgkin lymphomas NHL.Hodgkin lymphoma is clinically and histological distinct from the Non Hodgkins lymphoma, while Non Hodgkin lymphomas frequently occur at extranodal sites and spread in an unpredictable fashion Hodgkins lymphoma arises in a single node or chain of nodes and spreads first to anatomically contiguous nodes.Clinical difference between Hodgkins and Non Hodgkins lymphoma :Hodgkins lymphomaMore often localized to a single axial group of cervical, mediastinal, paraaortic nodesOrderly spread by contiguityMesenteric nodes and waldeyer ring rarely involved.Extranodal involvement uncommonNon Hodgkins lymphomaMore frequent involvement of multiple peripheral nodesNon contiguous spreadWaldeyer ring and mesenteric nodes commonly involved.Extranodal involvement commonThe prognosis of Non-Hodgkins lymphoma varies markedly with various histological types of Non Hodgkins lymphoma, In general lymphomas with a follicular histological pattern are of lower grade longer survival than those of diffuse pattern 