[456] T-Cell Subsets and Plasmacytoid Dendritic Cells in Rosacea and Cutaneous Lupus Erythematosus: A Comparative Immunophenotypic Analysis

Theodore Brown, Jr., Karen Choi, Dafydd Thomas, Alexandra Hristov, May Chan. University of Michigan Medical Center, Ann Arbor, MI

Background: Distinction of rosacea and cutaneous lupus erythematosus (LE) can be challenging due to clinical and histologic overlaps. Both conditions may present as facial edema or inflammatory papules, and typically demonstrate perifollicular and perivascular T cell-rich infiltrates histologically. Increased CD8+ cytotoxic T cells, decreased CD4+FoxP3+ regulatory T cells (Tregs), and increased CD123+ plasmacytoid dendritic cells (PDCs) have been reported in the skin lesions of LE. Similar data are lacking in rosacea. We hereby explore the utility of immunohistochemistry in differentiating rosacea and LE by comparing their T-cell subsets and the number of PDCs.
Design: The surgical pathology archive at University of Michigan was searched for cases of rosacea and facial LE. CD4, CD8, CD25, and CD123 immunostains were performed on all cases. The CD4:CD8 ratio in each case was estimated by counting positive cells on digital images taken of at least one representative lymphoid aggregate. Using the same method, the percentage of CD4+CD25+ regulatory T cells (Tregs) was determined by dividing the number of CD25+ cells by the number of CD4+ cells (CD25/CD4). The percentage of CD123+ PDCs of the total infiltrate was estimated in a semi-quantitative manner (0 to 100% in 10% increments). Any clustering of more than twenty CD123+ cells was also noted. All data were obtained by multiple authors blinded to the final diagnoses.
Results: Twenty-seven cases of rosacea and 30 cases of facial LE were selected after careful clinicopathologic review. The mean CD4:CD8 ratio is 2.80 in rosacea and 1.74 in LE (p=0.0272). The proportion of CD25+/CD4+ Tregs is 31% in rosacea and 13% in LE (p<0.0001). The percentage of CD123+ PDCs is 6% in rosacea and 18% in LE (p=0.0008). Clustering of CD123+ cells is seen in 18% of rosacea, and in 60% of LE (p=0.0026).
Conclusions: Cases of facial LE show significantly lower CD4:CD8 ratio, fewer CD25+ Tregs, and more CD123+ PDCs than rosacea. These findings support the implication of T cell-mediated cytotoxicity, decreased immune suppression by Tregs, and increased interferon-producing PDCs in the pathogenesis of LE. We propose that these findings may serve as useful adjunctive tools in distinguishing rosacea and LE in difficult cases.
Category: Dermatopathology

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 76, Wednesday Morning

 

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