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Background and Objectives: The REAL/WHO classification constitutes a new tool for the better understanding and treatment of malignant lymphomas. The authors focus on the key features of aggressive B- and T-cell lymphomas, aiming to contribute to the cross-talk between pathologists and clinicians., Data Sources and Methods: Each lymphoma entity is analyzed on the basis of the most representative contributions in the literature and the authors' experience gained in studying more than 20,000 lymphoid tumors over a 20-year period., Results: Guidelines for diagnosis and areas of interest for future clinico-pathologic studies are identified and discussed. Within this context, selected data obtained by the application of novel markers are presented., Interpretation and Conclusions: The present know- ledge and organization of malignant lymphomas now make the development of tailored therapies a feasible goal.

Background and Objectives: The REAL/WHO classification constitutes a new tool for the better understanding and treatment of malignant lymphomas. The authors focus on the key features of B-cell lymphomas with an indolent behavior, aiming to contribute to the cross-talk between pathologists and clinicians., Data Sources and Methods: Each lymphoma entity is analyzed on the basis of the most representative contributions in the literature and the authors' experience gained in studying more than 20,000 lymphoid tumors over a 20-year period., Results: Guidelines for diagnosis and areas of interest for future clinico-pathologic studies are identified and discussed. Within this context, selected data obtained by the application of novel markers are presented., Interpretation and Conclusions: The present know- ledge and organization of malignant lymphomas now make the development of tailored therapies a feasible goal.

Anaplastic large cell lymphoma (ALCL) shows a wide morphologic spectrum, including the occurrence of reactive components obscuring the neoplastic population. This makes its distinction from hyperimmune reaction difficult. The authors describe an ALCL in a girl wha had a tick bite 20 days prior to clinical presentation. She developed a huge epithelioid reaction (an unprecedented finding for this tumor). The diagnostic controversies were solved by applying the ALKc antibody against anaplastic large cell lymphoma kinase (ALK), in conjunction with reagents anti-nucleophosmin (NPM), which showed the typical staining pattern observed in ALCL carrying t(2;5). Comprised within the epithelioid component there were large anaplastic cells and small-medium sized atypical elements displaying strong nuclear and cytoplasmic positivity for ALK and NPM (N-terminal region). This pattern, never observed in normal lymphocytes, corresponds to the presence of the product of the hybrid gene NPM/ALK produced by t(2;5). Following the diagnosis, the patient - whose general conditions were critical - underwent aggressive chemotherapy, achieving complete remission.

Primary non-Hodgkin's lymphoma of the thyroid gland are infrequent tumors. They almost exclusively derive from B cells of mucosa-associated lymphatic tissue and only a very small minority of them is represented by T cell lymphomas. CD30 molecule, other than in Hodgkin's and Redd-Sternberg' cells, is strictly associated with anaplastic large cell lymphoma and ALK lymphomas, the latter being identified by the monoclonal antibody ALK1. We report a case of CD30-positive non-anaplastic (ALK1-negative) peripheral T cell lymphoma of the thyroid gland and speculate on aspects concerning diagnosis and the morphologic and immunohistochemical findings.