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T-Zellen-Lymphome sind relativ selten in unserem Untersuchungsgut, sie machen weniger als 20% aller Non-Hodgkin-Lymphome aus. Eine definitive Klassifikation der T-Zellen-Lymphome gibt es noch nicht. Man unterscheidet jedoch schon jetzt thymische und präthymische = lymphoblastische Lymphome von (postthymischen =) peripheren T-Zellen-Lymphomen. Unter den peripheren T-Zellen-Lymphomen sind folgende Subtypen relativ gut definiert: die T-CLL und die T-PLL, die Mycosis fungoides und das Sézary-Syndrom, das lymphoepi-theloide Lymphom (Lennerts Lymphom), das T-Zonen-Lymphom, das T-immunoblastische Lymphom und das anaplastische großzell·ige Lymphom (sog. Kil-Lymphom). Als Lymphogranulomatosis-X(AILD)-Typ wird neuerdings ein T-Zel-len-Lymphom abgegrenzt, das sich von den nichtneoplastischen Lym-phogranulomatosis X-Fällen durch klonale chromosomale Abnor-mitäten und durch Rearrangement der β-Kette des T-Zellen-Rezeptors auszuzeichnen scheint. Histologische und zytochemische Kriterien erlauben in vielen Fallen T-Zellen-Lymphome als solche zu identifizieren. Die Anwendung einer großen Zahl von monoklonalen Antikörpern erbrachte dagegen nicht viel mehr als die Sicherung der T-Zellen-Natur und die Proliferationsrate der Tumorzellen. Mit Hilfe der DNA-Rearrangement-Techniken gelingt es erstmals, polyklonale von monoklonalen T-Zellproliferationen zu unterscheiden. Das lymphoepitheloide Lymphom, der Lymphogranulomatosis-X-Typ und das großzeflige anaplastische Lymphom (Kil Lymphom) werden ausführlicher abgehandelt. Die Grenze von Morbus Hodgkin und peripheren T-Zellen-Lymphomen ist nicht so scharf, wie Lehrbücher glauben machen wollen.

A total of 56 cases of malignant lymphoma presumed to be of peripheral T-cell origin were investigated with regard to histological and immunohistochemical features. The goal of the study was to determine whether virus-associated T-cell lymphomas can be morphologically or immunohistochemically distinguished from presumably virus-negative T-cell lymphomas. The cases came from endemic and non-endemic regions of Japan, the United Kingdom (including 4 Caribbean cases) and the Federal Republic of Germany. Sera of all Japanese and Caribbean patients and 8 German patients were tested for antibodies to adult T-cell leukaemia virus-associated antigen HTLV-A. In all cases sections were examined blind by 5 well-trained histopathologists. In most cases cryostat sections could be prepared from fresh tissue specimens and stained with a large panel of monoclonal antibodies. All HTLV-A-positive cases were morphologically classifiable as the pleomorphic type of T-cell lymphoma. Approximately 70% of the tested cases of pleomorphic T-cell lymphoma, however, showed a positive serum reaction for HTLV-A. All other types of peripheral T-cell lymphoma (T-immunoblastic lymphoma, chronic lymphocytic leukaemia of T type, T-zone lymphoma, "AILD type" and lymphoepithelioid cell lymphoma) were HTLV-A-negative and mostly observed in European patients. Thus virus-associated T-cell lymphomas appear to be invariably of the pleomorphic type; but pleomorphism is not specific to HTLV-A-positive cases. This was also evident from the results of an experiment in which 2 Japanese histopathologists attempted to recognize HTLV-A positivity in a blind study of pleomorphic T-cell lymphomas. A maximum of about 80% of cases were correctly identified, with about 10% false-positive diagnoses (in HTLV-A-negative or presumably negative cases) and 10% false-negative diagnoses. The immunohistochemical analysis revealed not only many common features but also 2 distinct differences between HTLV-A-positive and -negative T-cell lymphomas. All but one of the HTLV-A-positive cases showed reactivity with anti-Tac and all cases in the virus-positive group were negative for TU14. All other cases were Tac-negative and approximately 65% of these cases exhibited reactivity with TU14. Preliminary cytogenetic observations suggest that there are also differences in specific chromosome aberrations.

Five cases of T-zone lymphoma were investigated with histologic, immunologic, and cytogenetic methods. The chromosome analyses were performed on lymphoma cells prepared immediately after removal of the lymph nodes. The chromosomes involved in structural rearrangements were nos. 1, 2, 3, 4, 14, and Y. Numbers 3, 5, 6, and 13 were lost by some tumors, and nos. 3 and 9 were gained. Chromosome 3 was involved most often in structural and numerical aberrations, whereas 14q + markers occurred in only one case. The importance of multidisciplinary studies is pointed out.

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