Follicular dendritic cell sarcoma of the abdomen: the imaging findings

Abstract

Follicular dendritic cell sarcoma is a rare neoplasm that originates from follicular dendritic cells in lymphoid follicles. This disease usually involves the lymph nodes, and especially the head and neck area. Rarely, extranodal sites may be affected, including tonsil, the oral cavity, liver, spleen and the gastrointestinal tract. We report here on the imaging findings of follicular dendritic cell sarcoma of the abdomen that involved the retroperitoneal lymph nodes and colon. It shows as a well-defined, enhancing homogenous mass with internal necrosis and regional lymphadenopathy.

Keywords: Abdomen, CT; Abdomen, US; Abdomen, neoplasms; Sarcoma.

Fig. 1

Follicular dendritic cell sarcoma in 69-year-old man. A. Abdominal ultrasonography shows 5 cm sized, well-defined anechoic mass (white arrows) that was located in posterior aspect of pancreas (P) with mild mass effect. Mass shows posterior acoustic enhancement that represents necrotic lesion. B. Axial CT scan shows well-defined necrotic mass with thin peripheral wall in retroperitoneal area (white arrows). Lesion shows mass effect on adjacent pancreas and splenic vein, but there was no evidence of direct invasion. C. Coronal reconstruction CT image shows several enlarged lymph nodes (black arrows) around cystic mass (white arrows). D. Gross specimen shows central whitish-yellow color that microscopically demonstrates extensive internal necrosis. E. Microscopic examination of solid component of mass reveals bundles of ovoid to spindle cells with pinkish cytoplasm (Hematoxylin & Eosin staining, ×100).

Fig. 2

Follicular dendritic cell sarcoma in 52-year-old woman. A. Pre-contrast axial CT image shows multiple foci of irregular and dense calcifications in mass (white arrows). B. Post-contrast axial CT image shows well-defined large mass in mid-descending colon. Mass is composed of intraluminal (white arrow) and extraluminal (black arrow) components. Intraluminal component is less enhanced than extraluminal component. C. Coronal reconstruction CT image shows several enlarged regional lymph nodes (black arrows) around mass (white arrow). D. Gross specimen shows intraluminal component with relatively dull yellow color (white arrow) and non-necrotic area of extraluminal component (black arrow) with pink-tan color. Several enlarged pericolonic lymph nodes (asterisks) are noted. E. Immunohistochemical staining for CD35 demonstrates positive cytoplasmic expression (×400).