Subcutaneous panniculitis by Epstein-Barr virus-infected natural killer (NK) cell proliferation in aggressive subcutaneous NK cell lymphoma

We describe here a case involving a patient presenting initially with subcutaneous panniculitis, which developed after 12 years into aggressive subcutaneous natural killer (NK) cell lymphoma with peripheral blood involvement and hemophagocytosis. The surface marker of lymphoid cells in peripheral blood was CD2+3-7+8-16+56+. Skin biopsies were taken in May 1986 and June 1998. The initial biopsy revealed a diffuse proliferation of atypical lymphoid cells in the subcutaneous tissue with panniculitis, while the second biopsy revealed the presence of large lymphoid cells in the subcutaneous tissue with necrotic changes, consistent with a diagnosis of malignant lymphoma (diffuse pleomorphic type). The lymphoid cells from these two specimens were positive for CD56 and such cytotoxic molecules as T-cell intracellular antigen-1 (TIA-1), granzyme B, and, interestingly, also positive for Epstein-Barr (EB) virus by in situ hybridization. This suggests that chronic EB virus infections play an important role in the early stages of tumorigenesis and in the progression of NK cell lymphoproliferative disorders. (C) 2000 Wiley-Liss, Inc.