Objective To investigate the imaging characteristics of small intestinal epithe-lioid angiosarcoma.

Methods The retrospective and descriptive study was conducted. The clinical data of 5 male patients with small intestinal epithelioid angiosarcoma who were admitted to 3 medical centers, including Yantaishan Hospital of Yantai et al, from January 2013 to December 2023 were collected. The age of 5 patients was 54 (range, 36-73)years. All 5 patients underwent computer tomography (CT) plain scan and dynamic contrast-enhanced scan, with 1 patient also undergoing magnetic resonance imaging (MRI) plain scan. Observation indicators: (1) results of CT and MRI examination; (2) surgical conditions and postoperative pathological examination; (3) follow-up. Measurement data with skewed distribution were represented as M(range), and count data were described as absolute numbers.

Results (1) Results of CT and MRI examination. Of the 5 patients with small intestinal epithelioid angiosarcoma, two cases were primary small intestinal epithelioid angiosarcoma and the other three cases were metastatic small intestinal epithelioid angiosarcoma. None of the five patients exhibited metastasis to other solid organs, and no significant ascites or peritoneal metastases. ① In two cases of primary small intestinal epithelioid angiosarcoma, three tumors were identified, appearing as round soft tissue nodules on CT plain scan, primarily growing intraluminally. The CT value for tumors of those two cases on plain scan were 30, 35, 32 HU, respec-tively. During the arterial phase of enhanced CT scan, moderate enhancement was observed for tumors of those two cases, with CT value of 57, 72, 65 HU, respectively. During the venous phase of enhanced CT scan, significant enhancement was observed for tumors of those two cases, with CT value of 76, 86, 88 HU, respectively. During the delayed phase of enhanced CT scan, slightly decreased enhancement was observed for tumors of those two cases, with CT value of 74, 79, 72 HU, showing no significant necrosis or cystic changes within the tumors. ② In three cases of metastatic small intestinal epithelioid angiosarcoma, four tumors were identified with uneven thickening of the intestinal wall appeared on CT plain scan. The CT value for tumors of those three cases on plain scan were 39, 37, 38, 28 HU, respectively. During the arterial phase of enhanced CT scan, mild to moderate enhancement was observed for tumors of those three cases, with CT value of 57, 56, 52, 45 HU, respectively. During the venous phase of enhanced CT scan, significant enhancement was observed for tumors of those three cases, with CT value of 84, 88, 82, 77 HU, respectively. During the delayed phase of enhanced CT scan, further changes of increased or decreased enhancement was observed for tumors of those three cases, with CT value of 95, 78, 72, 70 HU. One case of those three patients had thickened intestinal wall with low signal on T1-weighted imaging, heterogeneous high signal on fat-suppressed T2-weighted imaging, significant high signal on diffusion-weighted imaging and low signal on apparent diffusion coefficient imaging on MRI scan. (2) Surgical conditions and post-operative pathological examination. All five cases underwent complete tumor resection. In two cases of primary epithelioid angiosarcoma with three small intestinal tumor foci, there were two tumors invading the serosa and one tumor invading the submucosa. All three metastatic epithelioid angio-sarcoma cases showed four tumors invasion through the serosa, with one case exhibiting mesenteric lymph node metastasis. Microscopic examination revealed hemorrhagic necrosis on the tumor mucosal surface, with tumor cells located in the submucosa or throughout the intestinal wall, displaying infiltrative growth patterns. The distribution was diffuse, with local networks forming irregularly sized vascular-like structures, containing red blood cells and forming blood sinuses and vascular networks. Tumor cells were arranged in solid sheets, strands, and nests, exhibiting spindle-shaped or epithelioid characteristics, with marked atypia, large nuclei, prominent nucleoli, and mitotic figures. Immunohistochemical analysis showed diffuse strong positivity for CD31, Fli-1, and Vim in all five patients. (3) Follow-up. All five patients were followed up postoperatively for 6(range, 3‒48)months. During the follow-up period, four patients succumbed to widespread metastasis. One patient with metastatic small intestinal epithelioid angiosarcoma underwent six cycles of chemotherapy and remained in good condition four years post-surgery.

Conclusion The imaging characteristics of small intestinal epithelioid angiosarcoma include abnormal thickening or masses of the intestinal wall.