Prelymphoma, early lymphoma, and manifest lymphoma in immunosialadenitis (Sjögren's syndrome)--a model of lymphomagenesis.

The development of malignant lymphoma in myoepithelial sialadenitis with and without Sjögren's syndrome was investigated. At first, prelymphomatous proliferation areas showing a polytypic immunoglobulin (Ig) pattern were seen. These transformed into malignant lymphoma with a monotypic Ig pattern, at first in small, circumscribed proliferation areas ("early lymphoma") and later in large, confluent proliferation area ("manifest lymphoma"). The lymphomas were classified as LP immunocytoma. In some cases they transformed into high-grade malignant lymphomas of the same category, namely, B-immunoblastic lymphoma. The same types of lymphoma have been found in NZB mice and chronic graft-versus-host reactions. "Primary" malignant lymphomas of salivary glands that did not show myoepithelial sialadenitis were also studied. These lymphomas were mostly germinal center cell tumors and probably developed primarily in lymph nodes within parotid glands in most, if not all, cases.