The full name of diffuse lymphoma is diffuse large B-cell lymphoma, a group of highly heterogeneous aggressive lymphomas and the most common type of non-Hodgkin’s lymphoma. The etiology of diffuse large B-cell lymphoma is not well defined and has been linked to immunodeficiency, infection, occupational and environmental, genetic, and other risk factors. The most common clinical manifestation is enlargement of superficial lymph nodes, characterized by rapid growth of single or multiple lymph nodes over a short period of time, which are tough and nontender. The enlarged lymph nodes may show signs of compression or infiltration. The disease progresses rapidly and may involve multiple organs and systems, and may be accompanied by systemic symptoms such as fever, night sweats, and unexplained weight loss. Diagnosis of diffuse large B-cell lymphoma is based on pathologic examination of tissue biopsy specimens, and immunohistochemistry if further immunophenotyping is needed. Treatment of diffuse large B-cell lymphoma is based on chemotherapy; other treatments include biologic therapy and hematopoietic stem cell transplantation. Patients with diffuse large B-cell lymphoma should build up their confidence in treatment and undergo standardized treatment under the guidance of their doctors.