The CD30-positive lymphoproliferative disorders lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (C-ALCL), and systemic anaplastic large cell lymphoma (S-ALCL) are lesions that overlap clinically, histopathologically, and immunophenotypically. Their biologic behaviors, however, vary considerably. In particular, lesions of LyP regress spontaneously while those of S-ALCL persist and often progress. Apoptosis has been suggested as the mechanism by which the lesions of LyP regress, but the underlying signaling pathways remain unclear. In this study, we used newly developed activation state-specific antibodies to demonstrate apoptosis signaling through the death receptor-mediated pathway regulated by FADD and caspase 3.
Dual immunohistochemistry for CD30 and activated forms of FADD and caspase 3 was performed on cutaneous biopsy specimens from 27 patients with CD30-positive lymphoproliferative disorders involving the skin. The patients included 18 with primary cutaneous CD30-positive LPDs (15 with LyP and 3 with C-ALCL) and 9 with S-ALCL.
The proportion of CD30-positive cells expressing activated FADD was significantly different between primary cutaneous CD30-positive lymphoproliferative disorders and S-ALCL (36.4% vs. 14.5%, P = 0.0083). Expression of cleaved caspase 3 was also significantly different between primary cutaneous lesions and S-ALCL (9.2% vs. 1.9%, P = 0.048).
Although a larger number of cases should be studied to validate these results, these data provide evidence that differences in signaling through the death-receptor apoptosis pathway mediated by FADD may be responsible for the varying biologic behaviors of CD30-positive lymphoproliferative disorders involving the skin.