MUM-1 = multiple myeloma oncogene 1.
Also called IRF4 = interferon regulatory factor 4
High-grade follicular lymphoma (Grade 3) are:
(1) MUM-1 positive
(2) have a high Ki-67 index (around 56%)
(3) tend to show no or weak CD10 and weak bcl-6
where:
• Staining for MUM-1, CD10 and bcl-6 is considered positive if >=30% of lymphoma cells are show moderate to strong staining.
Low-grade follicular lymphomas are:
(1) MUM-1 negative
(2) have a lower Ki-67 index (around 26%)
(3) tend to express CD10 and bcl-6
For a germinal center (GC) type of follicular lymphoma the expression of MUM-1 and bcl-6 appear to be mutually exclusive. In diffuse large B-cell lymphomas both can be co-expressed in the non-GC type.
