Transformation in lymphomas--morphological, immunophenotypic and molecular features.

During the course of lymphoma, a clinically more aggressive process with different morphology may develop, referred to as lymphoma transformation. Clonal relationship and pathogenic mechanism of this process are widely debated. The aim of the study was to evaluate morphology, immunophenotype (including EBV status) and clonal relationship in nine cases of lymphoma transformation. Among the six patients with low grade B-cell lymphomas three transformed into high grade B-cell lymphomas (two into diffuse large B-cell lymphoma, one into Burkitt lymphoma) and three into Hodgkin lymphoma. Three other patients with Hodgkin lymphoma presented with transformation into diffuse large B-cell lymphoma in two patients and peripheral T-cell lymphoma in one patient. In all cases there was a sudden clinical change as well as change in morphology and phenotype. In five of the nine patients studied EBV-LMP1 was demonstrated by immunohistochemistry in large transformed lymphoma cells. In two cases molecular studies revealed a different pattern of immunoglobulin gene rearrangement in the large transformed cells as compared to the small cells of primary indolent lymphoma. Thus, they represented secondary, arising de novo neoplasm.

Angiodysplasia as a cause of recurrent bleeding from the small bowel in patients with von Willebrand disease. Report of 4 patients.

Angiodysplasia, characterized by the presence of malformed vessels in the submucosa of the gastrointestinal tract, may be a cause of recurrent bleeding. Bleeding angiodysplasia can be associated with von Willebrand disease (vWD) and this coincidence is probably the consequence of the lack of high molecular weight molecules of von Willebrand factor in the plasma. We report four patients with unexplained repeated massive intestinal bleeding, recurrent melena and iron deficiency anemia, which required numerous blood transfusions. All patients were adults (average age 68 years). Three patients have congenital von Willebrand disease (type 1, 2A and 3) and one idiopathic acquired von Willenbrand syndrome. Correct diagnosis was made 2-5 years after the onset of the symptoms and was confirmed by histopathological examination of surgically resected small bowel, where vascular lesions were located. Elderly patients with recurrent gastrointestinal bleeding and unexplained iron deficiency anemia should be diagnosed for angiodysplasia and vWD.

Primary mediastinal large B-cell lymphoma is an important differential among mediastinal tumours.

The study involved 51 patients with histopathologically verified diagnoses of primary mediastinal large B-cell lymphoma (PMBL). Clinically they presented as the anterior mediastinal tumours, frequently with the superior vena cava syndrome (21 patients) and usually (in 42 out of 51) without involvement of other locations. Morphologically the tumours were very pleomorphic. Histopathologically they were composed of germinal center cells, clear cells or polymorphic cells of various size and shape. However, there were also PMBLs composed of cells resembling Reed-Sternberg and Hodgkin cells and small cells. Various types of stromal sclerosis were evident in most biopsies. Due to lymphoma patterns mimicking other tumours with primary or secondary mediastinal location it was necessary to use a panel of immunocytochemical stains. CD20 staining proved to be indispensable for distinguishing PMBL. The patients were treated with CHOP or MEVA (V-VIII courses) followed by radiotherapy of the mediastinum (3600-4200cGy/t). Complete remission was obtained in 21 patients with overall survival ranging from 36 to 99 months. A total of 24 patients are alive, 3 of them live with persisting disease. One patients was lost to follow up, 26 died despite the treatment due to persistence of mediastinal tumour or dissemination to distant organs.