Follicular dendritic cell (FDC) sarcoma is rare and is classified either as conventional type or inflammatory pseudotumor (IPT)-like variant. Extranodal presentation is uncommon and nearly all gastrointestinal FDC tumors are of the conventional type. IPT-like variant tumors occur almost exclusively in the liver and spleen and are consistently associated with Epstein-Barr virus (EBV). Here we report the case of a 78-year-old woman with an IPT-like FDC sarcoma presenting as a pedunculated colonic polyp. Histologically, scanty atypical ovoid to spindle cells were mixed with a background of florid lymphoplasmacytic infiltrate, which led to an initial misdiagnosis of pseudolymphoma. These atypical cells expressed CD21, CD23, CD35, and D2-40, and were positive for EBV by in situ hybridization, confirming the diagnosis. The patient was free of disease five months after polypectomy without adjuvant therapy. Although extremely rare, the differential diagnosis for colonic polyp should include FDC sarcoma to avoid an erroneous diagnosis. A review of the 24 cases of IPT-like FDC sarcoma reported in the literature reveal that this tumor occurs predominantly in females with a predilection for liver and spleen, and has a strong association with EBV.

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Cutaneous peripheral T-cell lymphoma unspecified is a rare neoplasm that is infrequently associated with Epstein-Barr virus (EBV) infection. In contrast, extranodal natural killer (NK)/T-cell lymphoma, although also rare, is known to be strongly associated with EBV and occurs most commonly in the nasal region. We report the case of a 55-year-old male who presented with fever and an indurated cutaneous plaque with ulceration. This cutaneous neoplasm showed diffuse dermal lymphomatous infiltration and tumor necrosis, with neoplastic cells expressing CD2, cytoplasmic CD3 (CD3ε), CD8, CD16, CD30, T-cell intracellular antigen-1, and granzyme B but not CD56, BF1, or T-cell receptor (TCR) δ1. Furthermore, the tumor cells were noted to be diffusely positive for EBV by in situ hybridization. A monoclonal TCR gene rearrangement was demonstrated. The disease showed an aggressive clinical course, and the patient died within 3 weeks of diagnosis without complete staging or chemotherapy. According to the 2005 World Health Organization/European Organization for Research and Treatment of Cancer scheme for cutaneous lymphoma and the 2008 WHO classification for lymphoid neoplasms, our case would have been classified as a nasal type extranodal NK/T-cell lymphoma with T-cell lineage. However, the expressions of CD8 and CD16, in addition to a monoclonal TCR gene rearrangement, are unusual findings in NK/T-cell lymphoma, and we believe such a phenotype/genotype should be more appropriately classified as an EBV-positive peripheral T-cell lymphoma, unspecified with a cytotoxic phenotype. Detailed clinicopathologic and molecular studies of similar cases may shed light on the prognostic impact of NK vs. T-cell lineage on extranodal NK/T-cell lymphomas.