Abstract
Accumulating evidences suggest that some of extranodal malignant lymphomas develop in the sites of chronic inflammation. In this review, we describe the results of our study on the extranodal lymphomas developing from chronic inflammation, including pyothoraxassociated lymphoma (PAL), and lymphoma of thyroid gland, salivary gland, and gastrointestinal tract. PAL had developed over 20 years history of chronic (tuberculous) pyothorax. Histologically, all were non-Hodgkin's lymphoma with diffuse large cell type being the most common. Immunologic and immunohistochemical studies revealed that PAL have immunophenotype of exclusively B-cell. Epstein-Barr virus (EBV) genome was detected in the lymphoma cells in all PAL cases, which suggested the etiological role of EBV for the development of PAL. We established two cell line from two PAL cases (OPL-1, 2), in which monoclonal latent infection of EBV was identified. We characterized the profile of expression of EBV latent genes and cytokine including interleukin (IL)-6, and IL-10. To investigate the escape mechanism of latent gene expressing PAL cells from host immune surveillance, HLA-A allotype of patients and mutation of EBNA-4 gene were examined. The results suggested that mutation of EBNA-4 gene play a role for PAL development. Thyroid lymphoma and salivary gland lymphoma are closely associated with Hashimoto's disease and Sjogren's syndrome, respectively, known as autoimmune diseases. Our epidemiological study revealed the relative risk for the development of thyroid lymphoma in patients with Hashimoto's disease was 80 times higher than that in general population. Both type of lymphomas showed a female preponderance. The frequencies of lymphoma showing proliferation of small lympoid cells with irregular nucleus and relatively rich cytoplasm, so-called centrocyte-like cells, were relatively high in both type of lymphomas. This type of lymphoma is termed by Isaacson as low-grade lymphoma of mucosa-associated lymphoid tissue (MALT). The frequencies of low grade MALT lymphma in stomach, small intestine, and rectum is 47%, 0%, and 42%, respectively, in our series. Low- grade MALT lymphoma was closely associated with reactive lymphoid hyperplasia in the gastrointestinal tract. Clinicopathologic findings together with EBV status in nasal lymphoma were summarized. Our epidemiological study revealed the clustering of patients with polymorphic reticulosis, a type of nasal lymphoma and constitute lethal midline granuloma syndrome, in the East Asian countries including Japan, Korea, and China.
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Schedule a callMore From: The journal of the Japanese Society of Lymphoreticular Tissue research
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