Immunohistochemical Detection of Multiple Myeloma 1/Interferon Regulatory Factor 4 (MUM1/IRF-4) in Canine Plasmacytoma: Comparison with CD79a and CD20

Abstract

Abstract. Multiple myeloma oncogene 1/interferon regulatory factor 4 (MUM1/IRF4) is involved in lymphoid cell differentiation, particularly in the production of plasma cells. We examined the immunoreactivity of mouse monoclonal antibody Mum-1p to MUM1/IRF4 and compared it with expression of CD79a and CD20 in 109 plasmacytomas in 107 dogs. Tissues had been fixed in formalin and embedded in paraffin. One hundred one of 109 (93.5%) tumors were positive for MUM1/IRF4. The staining was nuclear with weak cytoplasmic reaction. Fifty-nine of 105 (56.2%) plasmacytomas were positive for CD79a; only 21 of 108 (19.4%) cases were positive for CD20. MUM1/IRF4 staining was performed on 139 other tumors including B-and T-cell lymphomas, histiocytic proliferations, mast cell tumors, and melanocytic tumors. The only MUM1/IRF4-positive nonplasmacytic tumors were 10 B-cell lymphomas and 1 anaplastic lymphoma. We conclude the following: 1) Antibody Mum-1p is very specific for canine plasmacytomas, 2) antibody Mum-1p is superior in sensitivity and specificity to CD79a and CD20 for the identification of canine plasmacytomas in formalin-fixed, paraffin-embedded tissues, 3) canine lymphomas that express MUM1/IRF4 are few and usually of B-cell origin, 4) other canine leukocytic and melanocytic tumors do not express MUM1/IRF4, and 5) prospective studies are needed to determine whether the expression of MUM1/IRF4, particularly in lymphomas, has prognostic significance.

Histomorphological and immunohistochemical characterization of 172 cutaneous round cell tumours in dogs

“…Other authors observed positive staining for CD79a in 59 (56.2%) of 105 cases of PCT (Ramos-Vara et al 2007). In the present study, the tumours deϐined as PCTs were positive for CD79a in 66.66% (6/9) of the cases, and the labelling was predominantly cytoplasmic diffuse.…”

“…Immunohistochemical markers such as CD79a (Schrenzel et al 1998) and immunoglobulins (Platz et al 1999) have been used as ancillaries in the diagnosis of this neoplasm. Variable immunohistochemical expression of the CD79a antigen has been found in PCTs, and positive staining CD79a was present in 56.2% to 80% of cases studied (Schrenzel et al 1998, Ramos-Vara et al 1998, Ramos--Vara et al 2007). The CBL also can be stained by CD79a and immunoglobulin markers.…”

“…However, cutaneous PCTs and CBL can be distinguished by histomorphologic appearance and clinical course (Brunnert & Altman 1991). Currently, the antibody MUM-1 has been indicated for speciϐic diagnostic of plasma cell tumours (Ramos-Vara et al 2007).…”

Morphology and immunoreactivity of canine and feline extramedullary plasmacytomas

“…Due to its nonspecific morphology, EMP is often misdiagnosed, therefore immunohistochemistry is necessary for definitive diagnosis (Morton et al 1986, Baer et al 1989, Ramos-Vara et al 2007). Tumour cells express CD79α, a transmembrane protein which is a part of B-cell antigen receptor (BCR).…”

Syk Interacts with and Phosphorylates Nucleolin To Stabilize Bcl-xL mRNA and Promote Cell Survival

“…Formalin-fixed, paraffin-embedded tissues were stained with hematoxylin-eosin and also prepared routinely for immunohistochemical analysis. The diagnosis of diffuse large B-cell lymphoma was based upon histomorphology and immunohistochemical detection of CD79a and/or CD20, as previously described (29). A second section was placed in RPMI 1640 and processed immediately for use in ex vivo bioassays.…”