Malignant lymphoma is a neoplasm that arises from the lymphatic tissues and is due to a proliferation of atypical cells of the lymphatic series. They extend not only locally and regionally, but often eventually to distant organs. Frequently they assume the forms of diffuse infiltrations, and some authors believe that in such cases a continuous lymphatic connection, including a retrograde process, can be demonstrated between the primary and secondary growths. Other forms are diffuse at the onset, and a definitely localized primary focus cannot be ascertained. Changes in the circulating blood stream are either absent or of no differentiating value, with the exception of a terminal leukemia seen in some cases.
The lesions have been extensively classified, but recently there has been a tendency among pathologists to consider these various conditions as different manifestations of the same pathologic process. Thus, the term malignant lymphoma has come into use.