Single case report documents primary splenic angiosarcoma with bleeding and advanced disease

A 42-year-old man with recurrent left upper abdominal pain and bleeding from complex splenic lesions was diagnosed with primary splenic angiosarcoma after open splenectomy, according to a 2026 case report and literature review. The tumor destroyed the splenic architecture and showed vascular differentiation, marked atypia, extensive necrosis, rupture with hemorrhage, and a Ki-67 labeling index of approximately 40%. The case illustrates the diagnostic difficulty of a rare primary malignant splenic tumor and the use of individualized systemic treatment after surgery.

Primary splenic angiosarcoma arises from splenic vascular endothelium or splenic sinus-related endothelial cells. The paper describes it as one of the rarest primary malignant tumors of the spleen, with a reported annual incidence of approximately 0.14–0.23 cases per million population. Its extreme rarity has limited prospective evidence; current knowledge is based mainly on pathology series, retrospective studies, reviews, and case reports. Reported clinical features include abdominal pain, splenomegaly, anemia, fatigue, weight loss, and spontaneous splenic rupture, while the liver, lung, bone, and bone marrow may be involved.

The patient initially presented in December 2023 with abdominal pain and no obvious trigger. CT and contrast-enhanced imaging described multiple splenic hemangioma-like lesions with local rupture and hemorrhage, along with splenomegaly, dilation of the portal and splenic veins, and decreased splenic density. Multiple hemangioma-like hepatic lesions were also present, although metastasis could not be excluded. He underwent emergency percutaneous splenic arteriography and embolization on December 14, 2023, then received anti-infective and supportive treatment before discharge.

Persistent dull pain returned in the left upper abdomen, worsening after eating greasy food and accompanied by nausea and vomiting. Repeat imaging in February 2024 showed post-embolization changes, possible local splenic infarction, and more numerous and larger hepatic low-density lesions. Patchy low-density areas with possible bone destruction were identified in parts of the thoracolumbar vertebrae, several ribs, and the right iliac bone. Bone scintigraphy showed active metabolism in the right third anterior rib and left ribs, while multiple other low-density bone lesions were considered tumor-related.

PET/CT demonstrated marked splenomegaly with increased metabolic activity, osteolytic bone destruction with partly increased metabolic activity, and focal activity in the left pleura. The imaging report considered lymphoma highly possible and recommended pathological confirmation. Bone marrow cytology did not support definite infiltration by a hematologic malignancy. Given the history of splenic bleeding and embolization, persistent pain, increasing lesion complexity, and the need for tissue diagnosis, a multidisciplinary team proceeded with surgery.

On March 12, 2024, the patient underwent open splenectomy and lysis of intestinal adhesions. Surgeons found approximately 4,000 mL of fresh bloody intraperitoneal fluid, an enlarged and edematous spleen, extensive adhesions, and active splenic bleeding. The resected spleen measured 22.2 × 15.8 × 6.2 cm. Microscopy showed anastomosing abnormal vascular channels, intraluminal papillary structures, focal solid growth, marked atypia, and extensive necrosis. Immunohistochemistry was positive for CD31, FLI-1, and ERG, with additional CD34 positivity, a Ki-67 index of approximately 40%, and mutant-type p53 expression. These findings supported the pathologic diagnosis of splenic angiosarcoma.

After surgery, the patient was clinically managed as having advanced disease with hepatic and bone involvement. Denosumab was started on May 8, 2024, with the aim of preventing skeletal-related events associated with suspected bone metastases. First-line EIM chemotherapy comprised ifosfamide, epirubicin, and mesna. Following two cycles, imaging showed enlargement of the hepatic lesions, and the response was assessed as progressive disease. The subsequent regimen combined gemcitabine, albumin-bound paclitaxel, and anlotinib. After two cycles, hepatic lesions were broadly similar to earlier images, and response was assessed as stable disease.

Supplementary pathology performed on September 4, 2024 showed PD-L1 positivity with a combined positive score of approximately 30 and a HER2 score of 0. The result was used for treatment selection rather than diagnosis. Sintilimab, a PD-1 inhibitor, was administered on September 13, 2024, nine days after the report, while anlotinib continued. Imaging on October 25, 2024 showed partial shrinkage of hepatic lesions, and assessments in January, May, and August 2025 recorded stable disease, with formal reports also describing some lesion shrinkage. The last documented treatment and follow-up date was October 10, 2025, when anlotinib plus sintilimab continued and the patient’s ECOG performance status was 1.

This single-patient report cannot establish the effectiveness of any treatment or define a standard regimen. Advanced primary splenic angiosarcoma has no disease-specific prospective trial evidence cited by the authors, so systemic therapy is generally informed by experience with angiosarcoma and soft-tissue sarcoma. The authors conclude that the diagnosis should be considered early for complex vascular splenic lesions accompanied by splenomegaly, recurrent pain, anemia, and bleeding or rupture. In this case, splenectomy established the diagnosis and controlled splenic bleeding, while subsequent multimodal treatment was associated with short-term imaging control rather than demonstrated tumor cure.

Subject of Research: A single case report of primary splenic angiosarcoma diagnosed after splenectomy and treated with multimodal systemic therapy.

Article Title: Case Report: Primary splenic angiosarcoma: a case report and literature review

Article References: Zha, J., Zhou, H., Yin, H., Zhou, Z., Xia, X., Zhao, H., & Xing, R. (2026). Case Report: Primary splenic angiosarcoma: a case report and literature review. Frontiers in Oncology, 16, Article 1927091. https://doi.org/10.3389/fonc.2026.1927091

Image Credits: AI Generated

DOI: 10.3389/fonc.2026.1927091

Keywords: primary splenic angiosarcoma, splenic rupture, splenectomy, vascular tumor, pathology, anlotinib, sintilimab, systemic therapy, case report, Case, Report, Primary