HTLV-I Induced Extranodal Lymphomas

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Abstract
HTLV-I induced not only nodal but also primary extranodal lymphomas. In this report we describe 12 patients with HTLV-I induced extranodal T-cell lymphoma collected from the literature and our institute experience. There were 5 males and 7 female patients of middle age positive for HTLV-1 antibody. The sites of primary tumor were gastrointestinal, Waldeyer's ring, skin, facial sinuses, and the pleura. All of these were histologically diffuse lymphomas and most of them were found to be a helper/inducer T-cell phenotype, showing integration of HTLV-I proviral DNA. Late leukemic changes and skin infiltration often occurred, but hypercalcemia was rare. Survival time varied from 4 to 35 months, and late organ infiltrations were common. These HTLV-I induced extranodal lymphomas were compared with HTLV-I unrelated extranodal lymphomas or HTLV-I induced nodal lymphomas (lymphoma type ATL). Between 1981 and 1990, we had 110 ATL patients and of these, 5 (4.6%) were HTLV-I induced primary extranodal lymphomas. The frequency of HTLV-I induced extranodal lymphoma might be much higher than expected because until now attention has not been paid to this entity. From the present review, it is suggested that HTLV-I could cause primary extranodal lymphoma which may have some different characteristics from other types of lymphoma. Therefore, patients with T-cell extranodal lymphomas should be investigated further for the presence of HTLV-I antibody and the tumor cells should be examined for the integration of HTLV-I proviral DNA using Southern blot analysis. However, this is sometimes difficult to detect with small specimens and in these cases the PCR method for detection of HTLV-I proviral DNA is worthwhile doing. It should be stressed that characterization of a monoclonal T-cell tumoral expansion with the integration of HTLV-I proviral DNA can be done by surface marker studies and gene analysis at the primary sites in patients with T-cell lymphoma and HTLV-I antibody. Further collection of cases with HTLV-I induced primary extranodal lymphoma is necessary in order to elucidate the clinical characteristics of this rare variant of ATL more precisely.