Lymphomas are a heterogeneous group of tumors arising in the reticuloendothelial and lymphatic systems. The major types are Hodgkin lymphoma and non-Hodgkin lymphoma (see table Comparison of Hodgkin Lymphoma and Non-Hodgkin Lymphoma).
Comparison of Hodgkin Lymphoma and Non-Hodgkin Lymphoma
Lymphomas were once thought to be absolutely distinct from leukemias. However, better understanding of cell markers and tools used to evaluate those markers now show that the distinction between these 2 cancers is often vague. The notion that lymphoma is relatively restricted to the lymphatic system and leukemias to the bone marrow, at least in early stages, is also not always true.
Malignant lymphoma cells can populate the bone marrow and the blood as well as the lymph nodes. This is more common in the low grade, or indolent, non-Hodgkin lymphomas, such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) or marginal zone lymphoma and the more aggressive mantle cell lymphoma.