title: Follicular Dendritic Cell Sarcoma of the Inflammatory Pseudotumor-like Variant Presenting as a Colonic Polyp.
abstract: 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.
authors.affiliation: Department of Pathology, Miao-Li General Hospital, Miaoli City, Taiwan.
authors.forename: Shien-Tung
authors.initials: ST
authors.lastname: Pan
authors.affiliation: Department of Surgery, Miao-Li General Hospital, Miaoli City, Taiwan.
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Cheng
authors.affiliation: Department of Surgery, Miao-Li General Hospital, Miaoli City, Taiwan.
authors.forename: Nie-Sue
authors.initials: NS
authors.lastname: Lee
authors.affiliation: Department of Pathology, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: Peir-In
authors.initials: PI
authors.lastname: Liang
authors.affiliation: Department of Pathology, Chi-Mei Medical Center, Tainan, Taiwan. ; Department of Pathology, Taipei Medical University, Taipei, Taiwan.
authors.forename: Shih-Sung
authors.initials: SS
authors.lastname: Chuang
keywords: Colon polyp; Epstein-Barr virus; Follicular dendritic cell sarcoma; Inflammatory pseudotumor; Taiwan