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.

Clinicopathological features of inflammatory pseudotumour‐like follicular dendritic cell tumour of the abdomen

“…Inflammatory pseudotumour‐like FDC tumour is a rare variant of FDC tumour. To date, 44 cases of inflammatory pseudotumour‐like FDC tumour have been reported in the English‐language literature . In contrast to the female predilection reported in the literature, the tumour predominantly affected males (male.female ratio of 2.3:1) in our series.…”

“…The difference might be attributable to the small number of cases and different regions. Inflammatory pseudotumour‐like FDC tumour occurs almost exclusively in the liver and spleen, and rarely involves the colon …”

Follicular Dendritic Cell Sarcoma of the Stomach: Case Report and Review of the Literature

“…The latter entity shows greater prevalence in liver and spleen and presents primarily in women. Histology shows atypical spindle cells scattered by prominent lymphoplasmacytic infiltrate, with expression of CD21, CD23, CD35, and D2-40 18 .…”

Epstein-Barr virus–associated inflammatory pseudotumor presenting as a colonic mass

“…Most of their aggressive cases involved the liver, whereas tumors presenting in the spleen had no recurrences. Notably, the GI case from Taiwan(9) and our case in the colon differed in phenotype (FDC vs. FRC/myofibroblastic markers), but were otherwise similar in terms of morphology and EBV status, further emphasizing the close relationship among these lesions.…”

“…The majority of previously reported GI tract IPTs likely represent non-specific inflammatory response to known irritants. We are aware of only a single prior case reported from Taiwan that documents an EBV-positive IPT in the gastrointestinal tract(9). In their report, the colonic polyp was diagnosed as IPT-like FDC tumor, with clinical and morphologic features highly similar to our case, albeit with FDC markers expressed by spindle cells.…”