Extranodal Follicular Dendritic Cell Sarcoma Originating in the Pancreas: A Case Report

Abstract

Follicular dendritic cell (FDC) sarcoma is a type of malignant tumor that originates from immune system-related FDCs. Pancreatic FDC sarcoma is a rare disease, and the specificity of the clinical presentation and laboratory results is unknown. We report the clinical process and imaging features of one case of pancreatic FDC sarcoma. A 67-year-old woman presented with a hypoechoic mass between the spleen and left kidney during a medical examination. The patient was hospitalized for further diagnosis. Her laboratory results did not present any obvious abnormal changes. Unenhanced and contrast-enhanced pancreatic computed tomography scans indicated a round mass with heterogeneous attenuation in the pancreatic tail, and a 3.5 × 3.6-cm solid mass with a cystic component was noted. Clear-cut, slight contrast enhancement was present in the solid part, whereas contrast enhancement was not observed in the cystic part. In addition, no obvious dilation was observed in the pancreatic duct, and no swollen lymph nodes were noted in the posterior peritoneum. Routine and contrast-enhanced pancreatic magnetic resonance imaging scans showed an abnormal signal indicative of a mass in the pancreatic tail, with a diameter of ∼35 mm and a clear boundary. A T2-weighted imaging scan showed a slight hyperintensity coupled with part of a hyperintensity, whereas T1-weighted imaging showed a slight hypointensity coupled with part of a hypointensity, and diffusion-weighted imaging showed a heterogeneous hyperintensity. The solid part of the lesion showed poor contrast enhancement through contrast-enhanced scanning, but contrast enhancement was not observed in the cystic part. Surgical tumor resection was performed, and the pathological diagnosis was pancreatic FDC sarcoma. The tumor did not recur based on short-term CT reexamination. Pancreatic FDC sarcoma is a rare disease, and the established clinical examinations and laboratory tests lack specificity. Imaging reveals a solid mass with a cystic component and a clear boundary. In addition, the solid part exhibits poor contrast enhancement. Although pancreatic occurrence is rare, a clinical pancreatic solid tumor with a cystic component should be identified by differential diagnosis.

FIGURE 1

Patient pancreatic CT. (A) The unenhanced pancreatic CT scan showed that a round soft tissue block existed in the pancreatic tail (white arrow) and that there was heterogeneous attenuation, striped hypodense visible, and a smooth tumor border with a clear boundary. (B, C) Contrast-enhanced CT showed that the tumor's solid part exhibited poor contrast enhancement and that contrast enhancement was not observable in certain areas (white arrow). CT = computed tomography.

FIGURE 2

MRI of patient's pancreas MRI. (A) Routine pancreatic MRI scan showed a round mass in the pancreatic tail. T1WI took on a slight hypointensity coupled with a part hypointensity. (B) T2WI presented a slight hyperintensity coupled with a part hyperintensity. (C) In terms of the DWI sequence, an obvious hyperintensity was visible for the solid part (white arrow). (D–F) Contrast-enhanced MRI showed that the solid part presented poor contrast enhancement and that no contrast enhancement occurred in the cystic part. DWI = diffusion-weighted imaging, MRI = magnetic resonance imaging, T1WI = T1-weighted imaging, T2WI = T2-weighted imaging.

FIGURE 3

(A) Tumor cells presented a spindle shape with a vortex arrangement. Cell pleomorphism was apparent (hematoxylin and eosin staining). (B) CD21 expression was diffusely positive in the tumor cells. (C) CD23 expression was diffusely positive in the tumor cells. (D) CD2 expression was negative in the tumor cells. CD2 = cluster of differentiation 2, CD21 =  cluster of differentiation 21, CD23 = cluster of differentiation 23.