Test Catalog

Test ID: MUM1    
MUM-1/IRF4 Immunostain, Technical Component Only

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids in the identification of hematolymphoid neoplasms and melanomas

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

MUM-1 (multiple myeloma oncogene-1), expressed by the IRF4 gene, is seen in a subset of B cells in the light zone of the germinal center (representing late stages of B cell differentiation), plasma cells, activated T cells, and a variety of hematolymphoid neoplasms derived from these cells. Among non-hematolymphoid neoplasms, MUM-1 expression has been reported in melanomas. A separate protocol optimized for B5 fixed/decalcified bone marrow specimens has been validated.

Interpretation Provides information to assist in interpretation of the test results

This test does not include pathologist interpretation; only technical performance of the stain is performed. If an interpretation is required, order PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen-dependent. Best practice is for paraffin sections to be cut within 6 weeks.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Rada G, Nagla S, Ali G: MUM1 and Ki67 Expression Best Predictors of Treatment Response in Diffuse Large B Cell Lymphoma Not Otherwise Specified. Amer J Clin Pathol 2015 Oct;144(2,1):A147

2. Cozzolino I, Varone V, Picardi M, et al: CD10, BCL6, and MUM1 expression in diffuse large B-cell lymphoma on FNA samples. Cancer Cytopathol 2016;124:135-143. doi:10.1002/cncy.21626

3. Heo MH, Park HY, Ko YH, et al: IRF4/MUM1 expression is associated with poor survival outcomes in patients with peripheral T-cell lymphoma. J Cancer 2017;8(6):1018-1024. doi:10.7150/jca.17358