MUM1, Interferon Regulating Factor 4, IRF4

MUM1 is a lymphocyte-specific transcriptional factor, a member of the interferon regulatory factor (IRF) family, known to play a role in the regulation of gene expression in response to interferons and other cytokines. MUM1 is through to contribute to the regulation of immunoglobulin gene expression in the final step (late centrocyte) of B-cell differentiation within germinal centre light zones, initiated by centrocyte-follicular dendritic cell contact. At this stage bcl-6 is downregulated.

Immunohistochemical expression

• A subset of germinal centre B cells

• Plasma cells

• Activated Tcells

• A wide range of haematolympoid neoplasms

• B cell lymphomas including:

  • plasmacytoma²

  • DLBCL of activated B cell type⁴

• T and NK cell lymphomas inacluding anaplastic large cell lymphoma and peripheral T cell lymphoma

• Reed Sternberg cells in classical Hodgkin lymphoma³

• Malignant melanoma²

•  

• It is not expressed by:

  • Burkitt lymphoma

  • mast cell disorders

  • histiocytic disorders

  • the popcorn cells of lymphocyte predominance Hodgkin lymphoma³

Diagnostic utility

References

¹ Petitjean, B., Jardin, F., Joly, B., Martin-Garcia, N., Tilly, H., Picquenot, J.M., Briere, J., Danel, C., Mehaut, S., Abd-Al-Samad, I., Copie-Bergman, C., Delfau-Larue, M.H. and Gaulard, P. Pyothorax-associated lymphoma: a peculiar clinicopathologic entity derived from B cells at late stage of differentiation and with occasional aberrant dual B- and T-cell phenotype. Am J Surg Pathol 2002;26:724-32.

² Natkunam Y, Warnke RA, Montgomery K, et al. Analysis of MUM1/IRF4 protein expression using tissue microarrays and immunohistochemistry. Mod Pathol 2001; 14:686-94

³ Carbone A, Gloghini A, Aldinucci D, et al. Expression pattern of MUM1/IRF4 in the spectrum of pathology of Hodgkin's disease. Br J Haematol 2002; 117:366-72

⁴ Hans CP, Weisenburger DD, Greiner TC, et al. Confirmation of the molecular classification of diffuse large B-cell lymphoma by immunohistochemistry using a tissue microarray. Blood 2004; 103:275-82

This page last revised 6.10.2006.

©SMUHT/PW Bishop