Intravascular large B-cell lymphoma (IVLBCL) is a rare form of diffuse LBCL characterized by preferential intravascular growth of malignant lymphocytes, aggressive behavior, and an often fatal course. IVLBCL usually affects elderly patients with poor performance status, elevated lactic dehydrogenase serum levels, anemia, and B symptoms. It displays some differences in clinical presentation among diverse geographical areas, mostly between patients diagnosed in Western countries and Japan. In addition, data from the literature suggest that pathologic diagnostic criteria as well as clinical features of this disease may be broader than described in current classification scheme(s). Under the sponsorship of the International Extranodal Lymphoma Study Group, clinicians and pathologists with interest in IVLBCL, coming from Western and Eastern countries, joined to reach a consensus on defining features as well as to focus on the most urgent unresolved issues in IVLBCL. To this end, a representative group of IVLBCL patients coming from both the aforementioned geographical areas were collectively analyzed. Additional features of IVLBCL were proposed both under clinical and pathologic stand points. At the meeting, it emerged that IVLBCL may have additional histopathologic/cytologic definition criteria with respect to those currently recommended, some clinical features are not randomly distributed worldwide, recent therapeutic approaches, such as anti-CD20–containing regimens, may improve outcome, and kidney, spleen, and liver involvement may show peculiar histopathologic features. Finally, a provisional practical diagnostic approach to hemophagocytosis-associated patients and a proposal for the most useful criteria in the settings of differential diagnosis are included.

Well‐established histopathological prognostic factors are lacking in primary central nervous system (CNS) lymphomas (PCNSL). The present study investigated the presence and prognostic role of tumour necrosis (TN) and reactive perivascular T‐cell infiltrate (RPVI), defined as a rim of small reactive T‐lymphocytes occurring alone or located between the vascular wall and large neoplastic cells, in tumour samples from 100 immunocompetent patients with PCNSL. World Health Organization histotypes of the patients were: 96 diffuse large B‐cell lymphomas, two Burkitt‐like lymphomas, one anaplastic large T‐cell lymphoma and one unclassified B‐cell lymphoma. TN was observed in 24 (24%) cases and RPVI in 26 (36%) of 73 assessable cases. Patients with RPVI‐positive lesions exhibited a significantly better overall survival (OS) than patients with RPVI‐negative lymphoma, particularly among patients treated with high‐dose methotrexate‐based chemotherapy (3‐year OS: 59 ± 14% vs. 42 ± 9%, P = 0·02). By contrast, the presence of TN did not demonstrate prognostic significance. Multivariate analysis confirmed an independent association between RPVI and survival. In conclusion, the presence of RPVI is independently associated with survival in PCNSL. This parameter can be easily and routinely assessed at diagnosis on histopathological specimens.

Purpose:Chlamydia psittaci (Cp) has been associated to ocular adnexal lymphomas (OAL) with variable geographic distribution. Herein, we used multiple Chlamydia detection tools to identify Cp elementary bodies–containing cell and to assess Cp prevalence in both nodal and extranodal lymphomas. Experimental Design: TETR-PCR, immunohistochemistry, immunofluorescence, electron microscopy, and laser-capture microdissection were done in 35 OALs to define their effect in Chlamydia detection and, moreover, to identify the Cp cellular carrier. Cp prevalence was screened by TETR-PCR in 205 extraorbital lymphomas and 135 nonneoplastic controls. Results: Twenty-six (74%) OALs were associated with Cp infection: immunohistochemistry, immunofluorescence, and laser-capture microdissection-assisted PCR showed that monocytes/macrophages were the Cp carriers; electron microscopy showed the presence of intact Cp elementary bodies into these cells. Immunohistochemistry and TETR-PCR showed a 70% concordance rate (P = 0.001). Cp DNA was equally prevalent in non-OAL, nodal, and extranodal lymphomas: among the latter, it was more common in diffuse large B-cell lymphomas of the skin (P = 0.03) and Waldeyer's ring. Conclusions: This multiparametric approach shows, for the first time, that monocytes/macrophages are the carriers of Cp, Cp seems preferentially associated with lymphomas arising in organs primarily exposed to antigens. The clinical implications of these findings deserve to be prospectively investigated.