Primary gastric lymphoma--a tumour of mucosa-associated lymphoid tissue. A histological and immunohistochemical study of 36 cases.

A series of 36 cases of non-Hodgkin's lymphoma of the stomach have been analysed using routine histological techniques and immunohistochemistry. All cases were categorized as follicle centre cell lymphomas. Apart from two cases who had nodal lymphomas followed by gastric lymphomas, all cases appeared to represent primary lymphoma of mucosa-associated lymphoid tissue. It is proposed that the morphology and behaviour of these tumours reflect their origin from gut-associated lymphoid tissue. Physiologically well-differentiated examples show monotypic plasmacytic differentiation. Infiltration of gastric glands by follicle centre cells forming characteristic lympho-epithelial lesions is, we believe, a pathognomonic feature of primary gastric lymphoma. The spread of these tumours is within the mucosa-associated lymphoid tissues involving, in particular, the nasopharynx and lung but seldom spreading to peripheral lymph nodes or bone marrow. This concept of gastric lymphomas as primary neoplasms of gut-associated lymphoid tissue has important implications with respect to the investigation and treatment of this disease.