The t(2;5)(p23;q35) translocation associated with CD30-positive anaplastic large cell lymphoma results in the production of a NPM-ALK chimeric protein, consisting of the N-terminal portion of the NPM protein joined to the entire cytoplasmic domain of the neural receptor tyrosine kinase ALK. The ALK gene products were identified in paraffm sections by using a new anti-ALK (cytoplasmic portion) monoclonal antibody (ALKc) that tends to react more strongly than a previously described ALK1 antibody with the nuclei of ALK-expressing tumor cells after microwave heating in 1 mmol/L ethylenediaminetetraacetic acid buffer, pH 8.0. The ALKc monoclonal antibody reacted selectively with 60% of anaplastic large cell lymphoma cases (60 of 100), which occurred mainly in the first three decades of life and consistently displayed a T/null phenotype. This group of ALK-positive tumors showed a wide morphological spectrum including cases with features of anaplastic large cell lymphoma "common" type (75%), "lymphohistiocytic" (10%), "small cell" (8.3%), "giant cell" (3.3%), and "Hodgkin's like" (3.3%). CD30-positive large anaplastic cells expressing the ALK protein both in the cytoplasm and nucleus represented the dominant tumor population in the common, Hodgkin's-like and giant cell types, but they were present at a smaller percentage (often with a perivascular distribution) also in cases with lymphohistiocytic and small cell features. In this study, the ALKc antibody also allowed us to identify small neoplastic cells (usually CD30 negative) with nucleus-restricted ALK positivity that were, by definition, more evident in the small cell variant but were also found in cases with lymphohistiocytic, common, and "Hodgkin's-like" features. These findings, which have not been previously emphasized, strongly suggest that the neoplastic lesion (the NPM-ALK gene) must be present both in the large anaplastic and small tumor cells, and that ALK-positive lymphomas lie on a spectrum, their position being defined by the ratio of small to large neoplastic cells. Notably, about 15% of all ALK-positive lymphomas (usually of the common or giant cell variant) showed a cytoplasm-restricted ALK positivity, which suggests that the ALK gene may have fused with a partner(s) other than NPM. From a diagnostic point of view, detection of the ALK protein was useful in distinguishing anaplastic large cell lymphoma cases of lymphohistiocytic and small cell variants from reactive conditions and other peripheral T-cell lymphoma subtypes, as well as for detecting a small number of tumor cells in lymphohemopoietic tissues. In conclusion, ALK positivity appears to define a clinicopathological entity with a T/null phenotype ("ALK lymphomas"), but one that shows a wider spectrum of morphological patterns than has been appreciated in the past.

The prognostic value of 12 clinical and haematological parameters, recorded at diagnosis, in myelofibrosis with myeloid metaplasia (MMM) was retrospectively analysed in a consecutive series of 133 patients followed for a minimum of 60 months. Multivariate analysis showed that the following features were associated with a significantly shorter survival: (1) short period of time (less than 13 months) between first symptoms and diagnosis; (2) anaemia (haemoglobin less than 10 g/dl); (3) leucocyte count greater than 12 x 10(9)/l; (4) peripheral blood granulocyte precursors greater than 10%. Age, splenectomy and percentage of peripheral blood metamyelocytes were found significantly to affect survival only from univariate analysis, whereas sex, size of spleen, thrombocytopenia and thrombocytosis were of no prognostic significance. These data suggest that a more intensive chemotherapy might be useful for younger patients with bad prognostic factors at diagnosis.

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MBL is an aggressive NHL with unique clinicopathologic aspects, often refractory to current CHT designed for high-grade NHL. Poor performance status and pericardial effusion predict NR and poor survival. Inadequate response after the first courses of front-line CHT predicts failure of subsequent treatment. Responders with bulky mediastinum or residual mediastinal abnormality after CHT are at risk of relapse. These factors should help to select high-risk patients for intensive treatments.