title: The expression of MUM1 in cutaneous T-cell lymphoproliferative disorders.
abstract: MUM1 is a member of the interferon regulatory factor family of transcription factors. It is normally expressed in plasma cells, late B cells, and activated T cells, and has been described in several B-cell malignancies. Although its expression has been reported in some T-cell neoplasms, the full range and character of expression have not been explored. We studied 58 cases of T-cell lymphoproliferative lesions, including systemic and cutaneous anaplastic large cell lymphoma, lymphomatoid papulosis (LyP), mycosis fungoides (MF), MF with large cell transformation, and Sézary syndrome (SS). Nearly all cutaneous (5/5) and systemic anaplastic large cell lymphomas (4/5) were positive for MUM1, mainly in the large cell population. Similarly, 12 of 16 types A and C LyP showed MUM1 reactivity in greater than 50% of the large cells. Focal MUM1 staining was seen in 3 type B LyP, mostly in reactive lymphoid cells. All 9 MF with large cell transformation expressed MUM1 in large cells, where it paralleled CD30 expression. In comparison, most MF (11/12) were MUM1 negative. Interestingly, all SS cases (8/8) were MUM1 positive, 3 of which demonstrated diffuse staining. There was a significant difference in MUM1 expression between MF and SS groups as well as between MF and large cell transformation of MF groups (P < .001 for both). In summary, MUM1 is not helpful in separating different types of CD30-positive lymphoproliferative disorders. Potentially, MUM1 could serve as an adjunct marker for SS and/or large cell transformation of MF.
authors.affiliation: Department of Pathology, University of Michigan Medical Center, Ann Arbor, MI 48109-0602, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Wasco
authors.forename: Douglas
authors.initials: D
authors.lastname: Fullen
authors.forename: Lyndon
authors.initials: L
authors.lastname: Su
authors.forename: Linglei
authors.initials: L
authors.lastname: Ma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D050835:Interferon Regulatory Factors / Q000032:analysis* / Q000378:metabolism; D016410:Lymphoma, T-Cell, Cutaneous / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000473:pathology; D000099218:Interferon Regulatory Factor-4
chemical_list: D014408:Biomarkers, Tumor; D050835:Interferon Regulatory Factors; D000099218:Interferon Regulatory Factor-4