Inflammatory Pseudotumor-like Follicular Dendritic Cell Tumor of the Spleen: Case Report and Review of the Literature

Abstract

A 74-year-old woman underwent contrast-enhanced (CE) computed tomography (CT) that revealed an enlarging splenic lesion. This splenic tumor was suspected as metastasis because the patient had been diagnosed with right breast cancer with lung and right axillary lymph node metastases 4 years earlier and had undergone surgery and hormone therapy at another hospital. T 2 -weighted imaging of magnetic resonance (MR) imaging demonstrated the tumor with slightly high intensity with a rim of low intensity at the margin. On dynamic contrast-enhanced (DCE)-MR imaging after intravenous administration of gadolinium diethylenetriamine pentaacetic acid, delayed enhancement was observed in the center and margin of the tumor. On positron emission tomography with 2-deoxy-2-[18F] fluoro-Dglucose (FDG) integrated with CT, the tumor showed high FDG uptake. Splenic metastasis was considered based on the imaging findings, lack of inflammation on laboratory data, and clinical course, so she underwent splenectomy. Histopathologically, the tumor was encapsulated by a fibrous structure, which was depicted as the rim at the tumor margin on T 2 -weighted imaging and DCE-MR imaging. Immunohistochemical study allowed the diagnosis of inflammatory pseudotumor (IPT)-like follicular dendritic cell tumor (FDCT). FDCT is a primary neoplasm of lymph nodes that shows features of follicular dendritic cell differentiation, and it is rare at the spleen. Differential diagnosis is difficult between IPTlike FDCT and similar splenic tumors, such as IPT, splenic metastases, hamartoma and hemangioma. However, in addition to the enhancement pattern within a tumor on DCE-MR imaging, detection of the capsular-like rim on MR imaging might aid the diagnosis of splenic IPT-like FDCT.

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

“…To date, 44 cases of inflammatory pseudotumour-like FDC tumour have been reported in the English-language literature. [3][4][5][6][7][8][9][10][11][12] In contrast to the female predilection reported in the literature, 2,6,11 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 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.…”

Inflammatory pseudotumor-like follicular dendritic cell tumor: an underdiagnosed neoplasia

“…From 1996 to date we retrieved 22 publications reporting IPT-like FDC tumors [11,15,35,[89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107]. There were 46 patients described: 24 female, 22 male (ratio 1.1:1), median age 57y (range 29-79y).…”

Splenic Epstein-Barr Virus–Associated Inflammatory Pseudotumor

“…6,15,16 They are without distinguishing magnetic resonance imaging or computed tomography (CT) imaging features. 7,14,16,22 Epstein-Barr virusassociated splenic IPTs appear hypermetabolic on fluorodeoxyglucose F 18 positron emission tomography integrated with CT. 10,13,14,22 Lymphoma and metastasis, the most important preoperative malignant differential diagnoses, are indistinguishable from EBV-associated IPT by imaging. The diagnosis of splenic EBV-associated IPT is typically only made after splenectomy.…”

“…Fifteen well-documented cases have been reported in the spleen. [1][2][3]7,[18][19][20][21][22][23] The phenotype of the spindle cells in splenic EBV-associated IPT not expressing FDC markers is heterogeneous and controversial. Lesions with a presumed fibroblastic, 1 myofibroblastic (''splenic inflammatory myofibroblastic tumor''), 1,2,20,21 fibroblastic reticular cell (FBRC), 17 or ''fibrohistiocytic'' phenotype have been reported.…”