MGMT promoter hypermethylation appears to be a useful marker for predicting survival in patients with B-DLCL treated with multidrug regimens including cyclophosphamide.

No abstract

The entity known as sinus histiocytosis with massive lymphadenopathy (SHML), or Rosai-Dorfman disease (RD disease), is an uncommon benign proliferation of hematopoietic and fibrous tissue that often presents in the head and neck region. Its initial manifestations most often include a roughly symmetric, painless, bilateral cervical adenopathy, although extranodal disease may develop in a minority of patients. The key histologic feature of SHML is the presence of various numbers of large, pale histiocytic cells that contain within their cellular borders apparently engulfed lymphocytes ("emperipolesis"); these distinctive large, pale cells - RD cells - are S-100 protein-positive by immunostaining and so differ from ordinary histiocytes. Despite its sometimes impressive clinical presentation, SHML is a benign and self-limited disease, whose treatment is aimed largely at controlling its local manifestations (most often by surgical therapy). The microscopic differential diagnosis, particularly in extranodal disease, is at times challenging and can include Langerhans' cell histiocytosis, Hodgkin's disease, non-Hodgkin's lymphoma, metastatic carcinoma, and metastatic malignant melanoma.

Analysis of the immunoglobulin receptor (IGR) variable heavy- and light-chain sequences on 17 hepatitis C virus (HCV)-associated non-Hodgkin lymphomas (NHLs) (9 patients also had type II mixed cryoglobulinemia [MC] syndrome and 8 had NHL unrelated to MC) and analysis of intraclonal diversity on 8 of them suggest that such malignant lymphoproliferations derive from an antigen-driven pathologic process, with a selective pressure for the maintenance of a functional IgR and a negative pressure for additional amino acid mutations in the framework regions (FRs). For almost all NHLs, both heavy- and light-chain complementarity-determining regions (CDR3) showed the highest similarity to antibodies with rheumatoid factor (RF) activity that have been found in the MC syndrome, thus suggesting that a common antigenic stimulus is involved in MC syndrome and in HCV-associated lymphomagenesis. Moreover, because HCV is the recognized pathologic agent of MC and the CDR3 amino acid sequences of some HCV-associated NHLs also present a high homology for antibody specific for the E2 protein of HCV, it may be reasonable to speculate that HCV E2 protein is one of the chronic antigenic stimuli involved in the lymphomagenetic process. Finally, the use of specific segments, in particular the D segment, in assembling the IgH chain of IgR seems to confer B-cell disorders with the property to produce antibody with RF activity, which may contribute to the manifestation of an overt MC syndrome.