[467] Epidermal and Dermal CD8+/CD3+ Ratios as Diagnostic Indicators of Mycosis Fungoides.

Nils Becker, Carl O Deetz, Dongsi Lu. Washington University School of Medicine, St. Louis, MO

Background: The diagnosis of mycosis fungoides (MF) presents a significant challenge in dermatopathology. In its early stages, the histopathologic features often overlap with inflammatory dermatoses. The differentiation of MF from reactive dermatoses requires several histologic and immunohistochemical criteria. The ratio of CD8+ to CD3+ lymphocytes in the epidermis and dermis has been suggested to aid in this evaluation. This study further assessed the utility of CD8+ to CD3+ T cell ratios to distinguish MF from inflammatory dermatoses in a larger case series than previously described.
Design: Forty cases with MF, as well as 20 control cases with inflammatory dermatoses were retrieved from our files and evaluated for immunohistochemical staining patterns for CD8+ and CD3+ T cells. The epidermal and dermal lymphocytic infiltrates were assessed separately by two methods. In the epidermis, CD8+ as well CD3+ T cells were manually counted under high-power (40x objective) and the ratio was calculated. In the dermis, the CD8+/CD3+ T cell ratio was determined by visual estimate and grouped in 10% increments. All values were independently re-analyzed by two additional observers.
Results: A dermal lymphocytic infiltrate with intraepidermal lymphocytes was observed in all cases (60/60). Only one case in the MF group showed a complete absence of CD8 positive lymphocytes within the epidermis. Evaluation of the epidermis showed significantly lower CD8+/CD3+ ratios in the MF cases with an mean of 14% (SD=14). The control group exhibited a mean of 50% (SD=13). This contrast was less pronounced in the dermis with a mean of 15% (SD=9) in the MF cohort compared to 29% (SD=13) in the control group.
Conclusions: Our study confirms that evaluating the CD8+/CD3+ T cell ratio in the epidermis represents a useful tool to assist in the diagnosis of MF, while the diagnostic value of the CD8+/CD3+ ratio in the dermal component is ambiguous. Since rare cases in our series show some overlap, the epidermal CD8+/CD3+ T cell ratio should be used in conjunction with other existing histologic criteria for the diagnosis of MF.
Category: Dermatopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 103, Wednesday Afternoon


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