[509] CD25 Expression in Cutaneous B-Cell Lymphomas

PW Harms, DA Wada, KJ Busam, M Lim, L Ma. University of Michigan Health Systems, Ann Arbor, MI; Mayo Clinic Foundation, Rochester, MN; Memorial Sloan-Kettering Cancer Center, New York, NY

Background: CD25, the alpha subunit of interleukin receptor-2, is expressed on activated T-cells, B-cells, and monocytes. CD25 expression is observed in some systemic and cutaneous T-cell malignancies. Denileukin diftitox (Ontak), an agent targeting CD25, has been approved for use in T-cell lymphomas, and has demonstrated activity against some B-cell lymphomas. CD25 reactivity in B-cell malignancies is not well understood and, to our knowledge, its expression in cutaneous B-cell neoplasms has not been explored.
Design: We conducted immunohistochemical staining for CD25 expression in 6 cases of cutaneous benign lymphoid hyperplasia (LH), 7 primary cutaneous low-grade B-cell lymphomas (C-BCL), 9 cutaneous diffuse large cell B-cell lymphomas (DLBCL)-leg type, 6 primary cutaneous DLBCL-other, 5 systemic B-cell lymphomas (S-BCL) with secondary skin involvement, and 6 systemic DLBCLs with skin involvement. CD25 positivity was defined as at least 10% of lesional cells expressing CD25.
Results: Among primary cutaneous B-cell lymphomas, CD25 stained 5/9 DLBCL-leg type and 1/6 DLBCL-other (which was a case of EBV+ angioinvasive DLBCL). Two systemic DLBCLs (2/6) were positive for CD25. All cases of lymphoid hyperplasia, C-BCL, and S-BCL displayed scattered CD25+ small lymphocytes (likely activated T cells), which comprised less than 10% of infiltrating cells.
Conclusions: 1. CD25 expression was more frequent in cutaneous DLBCL-leg type relative to cutaneous DLBCL-other. 2. CD25 reactivity may be observed in both cutaneous DLBCL-leg type and systemic DLBCL with skin involvement, and cannot be used to distinguish the two. 3. No significant CD25 expression was found in cutaneous low-grade B-cell lymphomas or benign lymphoid hyperplasia in this small study. 4. CD25 may serve as a potential therapeutic target in cutaneous DLBCL-leg type.
Category: Dermatopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 96, Wednesday Afternoon


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