Objective:To explore the CT features of inflammatory pseudotumor like follicular dendritic cell sarcoma (FDCS) of the spleen.Methods:The clinical data of 12 patients with splenic inflammatory pseudotumor like FDCS admitted to 3 central hospitals including Yongjia People's Hospital in Zhejiang Province from January 2015 to December 2022 were retrospectively analyzed, including 4 males and 8 females, with a median age of 60 years old. The number, shape, size and CT features of the lesions were analyzed based on patient's CT image data.Results:CT scans of 12 patients showed 15 lesions, including 10 single lesions and 2 multiple lesions. The lesions were circular in 5 cases, elliptical in 4 cases, and irregular in 3 cases. The median maximum diameter of the mass is 6.5 cm. On plain scan, all 12 tumors showed low density or slightly low density. The CT value is (41.3±7.2) HU; 8 cases had uneven density and 4 cases had uniform density. There were 8 cases with clear tumor boundaries and 4 cases with unclear boundaries. There were 8 cases with tumor necrosis and cystic transformation, and 5 cases showed patchy bleeding lesions in the center of the tumor. Enhancement: the arterial phase shows small patches or flocculent enhancement at the edges or parenchymal parts of the tumor, with CT value of (56.0±3.8) HU. Among them, there were 7 cases of mild enhancement, 4 cases of moderate enhancement, and 1 case of significant enhancement. During the portal phase, there was mild to moderate persistent small patchy uneven enhancement, with CT value of (62.0±4.3) HU. Among them, there were 8 cases of mild enhancement and 4 cases of moderate enhancement. The delayed phase showed a slow withdrawal of enhancement, with CT value of (45.0±8.2) HU. All 12 cases underwent complete resection and were diagnosed with FDCS through pathological examination.Conclusion:FDCS plain scan shows circular or elliptical uneven low-density masses, with small patches or flocculent light to moderate uneven enhancement in the arterial phase, continuous enhancement in the portal phase, and slow withdrawal in the delayed phase as the main characteristics.

Objective:To study the CT manifestations of malignant hepatic perivascular epithelioid cell carcinoma (PEComa).Methods:Clinical data of nine patients undergoing surgery with histologically confirmed malignant hepatic PEComa in Yueqing People's Hospital, Wenzhou People's Hospital, and Yongjia County People's Hospital from January, 2010 to June, 2022 were retrospectively collected, including two males and seven females with a median age of 47 (43, 56) years old. The CT findings, including tumor size, shape, boundary, density, and enhancement patterns, were analyzed.Results:CT scans showed that all nine tumors were single lesions. Five tumors were located in right liver lobe, three in left lobe, and one in caudate lobe. The median tumor diameter was 5.7 (range, 3.3-16.0 ) cm. In terms of tumor shape, three were round, four were quasi-circular, and two were irregular. Eight tumors had well-defined boundaries, while one was ill-defined. Nine tumors showed uneven densities and were lower than the adjacent liver parenchyma. Four tumors had a false capsule, one contained fatty tissue, and six had necrotic and cystic changes. In the arterial phase of contrast-enhanced CT scanning, two tumors showed moderate enhancement and seven showed significant enhancement. In the portal venous and delayed phases, enhancement decreased significantly in four cases, showing a " fast-in and fast-out" pattern. In four cases, the enhancement persisted, showing a " fast-in and slow-out" pattern. One case showed no enhancement in any phase but had a strip-like enhanced vessel inside the tumor. Five cases had significantly thickened vessels around the tumor.Conclusion:The CT manifestations of PEComa are as follows: round or quasi-circular lesions with well-defined boundaries, uneven low densities, significant enhancement in the arterial phase and rapid washout or persistent enhancement in the portal venous and delayed phases.