Neoplastic diseases of the haematopoietic and lymphoid tissues.

Systemic lymphosarcomas are common in all species of domestic mammal. A binomial classification of these tumours, based on both the anatomical form (i.e., distribution of lesions) and the type of cytology, is proposed. Mast cell tumours also are common, especially in the dog. The categories of lymphoid neoplasms described are: lymphosarcoma, lymphoid leukaemia, nodular lymphoid hyperplasia, tumours of the immunoglobulin-forming cells, and thymoma. The myeloid neoplasms described are: myeloid leukaemia, erythroleukaemia, acute erythraemia, polycythaemia vera, megakaryocytoid leukaemia, panmyelosis, myelosclerosis, and monocytoid leukaemia. Mast cell tumours are divided into mastocytoma and malignant mastocytosis.