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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
ALK-positive anaplastic large cell lymphoma with PAX-5 expression: report of a case
No full textALK-positive anaplastic large cell lymphoma (ALCL) is a well-defined entity included in the 2008 WHO classification, comprising about 5% of non-Hodgkin lymphomas and 10 to 30% of childhood lymphomas. Although lacking several T-cell antigens, it is generally considered a T-cell derived neoplasm. Since both ALCL and Hodgkin lymphoma (HL) strongly express CD30, and they can show overlapping morphological features, the B-cell specific marker PAX5 is widely used for distinguishing the two entities. PAX5 is considered the most specific B-cell marker, and is defined as "the guardian of B-cell identity".
We report an exceptional case of ALK-positive ALCL with PAX5 expression. A 38-years old patient presented with fever and generalized lymphadenopathy lasting for two months at the time of biopsy. A basic cytofluorimetric analysis was performed, showing the presence of a large cell population with dim CD5 and CD4 expression. Histopathological evaluation revealed an effaced lymph node architecture, due to the presence of a neoplastic infiltration by medium-sized cells in wide aggregates; occasionally larger cells with "hallmark" morphology were present; intrasinusoidal involvement was evident. These atypical cells showed a strong staining for CD30, as well as perforin, while granzyme B was only focally expressed. Other T-cell markers (CD2, CD3, CD5, CD7, ZAP70) and B-cell markers (CD20, CD79a) were negative, with the notable exception of PAX5, which showed a dim but specific staining, similar to that observed in HL. ALK was diffusely expressed in neoplastic cells, with a predominantly cytoplasmic granular staining. Double chromogenic stains and immunofluorescence were also performed to confirm the findings. ALK-positive diffuse large B-cell lymphoma was ruled out because this case didn't show the typical immunoblastic/plasmablastic morphology, didn't express plasma cell markers and was diffusely CD30-positive. The patient was unfortunately lost at follow-up.
Four cases of PAX5-positive ALCL were recently described, of which only one was ALK-positive, diagnosed on a vertebral lesion. A previous study had identified three PAX5-positive ALK-negative ALCL, but no ALK-positive cases. To our knowledge, this case is the first description of lymph node involvement by PAX5-positive and ALK-positive ALCL. Our data show that the morphological presentation is totally overlapping with classical ALCL; we also confirm that PAX5 can be rarely expressed in ALCL and should not be taken as a final proof of the B-cell origin of a neoplastic population
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