Naresh used MUM-1 expression to evaluate follicular lymphomas. This stain can help to divide these tumors into low and high grade. The author is from Hammersmith Hospital and Imperial College London.


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



• 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.


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