Both classifications, Kiel and IWF, have their advantages and disadvantages, страница 7

T-zone lymphomas sooner or later transform into high-grade malignant lymphomas mostly of the T-immunoblastic type. However, patients with T-zone lymphomas have a higher survival rate than patients with high-grade malignant T-cell lymphomas [132]. T-zone lymphoma is not listed in the IWF. Some of the cases could be categorized as malignant lymphoma - diffuse, mixed small and large cell.

Lymphoepithelioi'd Lymphoma (Lennert's Lymphoma)

This is a rare lymphoma with an incidence peak in middle age. It is usually characterized by a generalized lymphadenopathy. Skin, liver and spleen involvement is common [133]. Histologically, the lymph nodes are diffusely infiltrated. There are numerous epithelioid cells distributed singly or in small foci. Among them various numbers of small to medium-sized neoplastic T cells are found (Fig. 9). They are relatively atypical and show mitoses. Immunohistochemically these cells display a phenotype of mature T cells: CD2+, CD3+, CD5+ and CD4+ [133,134]. Ki-67 positivity is almost exclusively seen in the CD4-positive neoplastic cells and not in the coexistent CDS-positive reactive cells. TCP gene rearrangement studies have confirmed the T-cell origin of Lennert's lymphoma [135,136]. Some neoplastic cells have a pale to clear cytoplasm and may even become larger and immunoblastic. In very rare cases may the cells resemble Stemberg-Reed cells. Small numbers of eosinophils and plasma cells may be found. Formally this kind of lymphoma was confused with Hodgkin's disease and angioimmunoblastic lymphadenopathy [137,138] or even with LP-immunocytoma [134, 138] containing numerous epithelioid cells. Development into a high-grade malignant lymphoma of the T-immunoblastic, Ki-1+ large cell anaplastic and large T-cell pleomorphic type is not infrequent [133,139]. The prognosis of Lennert's lymphoma is rather unfavorable. Survival depends on the clinical stage of the disease and its median value does not exceed 12 months. It is said that sufficiently aggressive therapy may improve the survival rates [140, 141]. According to the IWF Lennert's lymphoma in its typical form .could be categorized as "diffuse, mixed small and large cell malignant lymphoma".

T-cell Lymphoma of AILD Type (AILD-like ML)

Immunoblastic [142] or angioimmunoblastic [143] lymphadenopathy appears clinically as a systemic disease with generalized lymphadenopathy, spleen and liver enlargement, Coombs-positive hemolytic anemia, polyclonal hyperglobulinaemia, drug hypersensitivity and skin eruptions. Histologically the effacement of the lymph node architecture is complete or almost complete. Some "burnt-out" [143] pale stained germinal centers may be found. Arborizing vessels of the post-capillary venule type show strong proliferation even outside the lymph-nodal capsule. PAS-positive amorphous material in thickened vascular walls and among cells characterizes most of the cases. The infiltrating cell population is polymorphs, consisting of lymphocytes, plasma cells, dispersed immunoblasts, histiocytes and eosinophils [142-144]. In some cases the presence of epithelioid cells is prominent [142, 145]. AILD, occurring more frequently in elderly patients, was initially considered as a hyper-immune reaction [142-143] due to drugs or other immunogens. After the first description in Japan of peripheral T-cell lymphoma resembling immunoblastic lymphadenopathy [146], it became gradually obvious that the majority of so-called AILD represent a real T-cell lymphoma. The elements which favor such a view are: a) in most cases and in the vicinity of the proliferating vessels accumulations of atypical T cells with clear cytoplasm are found (Fig. 10);