Splenic angiosarcoma is the most common primary malignant neoplasm of the spleen, though it accounts for less than 2% of all primary splenic malignancies. It is an extremely aggressive, high-grade vascular endothelial tumor, with most patients presenting with widespread metastases at diagnosis. Median survival is less than 6 months. Clinically, it presents with splenomegaly, abdominal pain, anemia, and thrombocytopenia. Spontaneous splenic rupture and massive hemoperitoneum occur in 25-30% of cases, requiring emergent surgery. Thorotrast (former contrast agent), vinyl chloride, arsenic exposure, and prior radiation therapy are established risk factors. On imaging, it appears as a heterogeneous, necrotic, and hemorrhagic mass or multifocal nodules with markedly enlarged spleen.
Age Range
40-80
Peak Age
60
Gender
Male predominant
Prevalence
Rare
Angiosarcoma is a high-grade malignant tumor arising from vascular endothelial cells. The splenic parenchyma possesses a rich sinusoidal vascular architecture, and this sinusoidal endothelium constitutes the microenvironment from which the tumor originates. Neoplastic endothelial cells proliferate uncontrollably, forming anastomosing vascular channels and solid areas. The tumor contains both intense neovascularity and simultaneously immature, incompletely formed vessels — this explains the heterogeneous enhancement pattern on imaging, with early arterial uptake coexisting with necrotic and hemorrhagic zones. The fragile tumoral vessels are prone to spontaneous rupture; hence intratumoral hemorrhage and capsular rupture are frequent. Hemorrhagic areas produce T1 hyperintensity (methemoglobin) and mixed T2 signal on MRI. Iron deposition and hemosiderin-laden macrophages create T2 hypointense foci in chronic hemorrhage regions. The high cellularity and dense nuclear composition of the tumor cause restricted diffusion, yielding hyperintense signal on DWI.
Among primary splenic malignancies, spontaneous rupture is most common in angiosarcoma (25-30%). Fragile tumoral vascular structures and tumor extension to the capsule predispose to rupture. CT shows capsular discontinuity, active contrast extravasation, and high-density hemoperitoneum (35-60 HU). This finding presents clinically with acute abdomen + shock and is an indication for emergent splenectomy.
On non-contrast CT, the spleen is markedly enlarged (>15-20 cm) with heterogeneous density mass or multifocal nodules within the parenchyma. High-density areas within the tumor (60-80 HU) represent acute-subacute hemorrhage. Low-density areas correspond to necrosis and cystic degeneration. Calcification is uncommon but, particularly in Thorotrast exposure cases, high-density calcifications may be seen at the splenic periphery.
Report Sentence
The spleen is markedly enlarged with a heterogeneous density mass lesion containing areas consistent with hemorrhage and necrosis within the parenchyma.
In the arterial phase, the solid components of the tumor show intense and heterogeneous enhancement. Consistent with the vascular tumor architecture, peripheral and nodular enhancing areas are observed, while central necrotic-hemorrhagic areas remain non-enhancing. The enhancing solid areas are equal to or denser than the splenic parenchyma. In the multifocal nodular form, each nodule may show a different enhancement pattern.
Report Sentence
Intense heterogeneous enhancement of the solid components of the splenic mass is observed on arterial phase, consistent with a vascular tumor; large necrotic-hemorrhagic areas remain non-enhancing.
In the portal venous phase, contrast accumulation continues in the solid tumor components (progressive fill-in) and enhancement becomes more homogeneous. However, necrotic and hemorrhagic areas remain non-enhancing in all phases — this is a differentiating feature from benign hemangioma. In the presence of hemoperitoneum, perihepatic and pelvic free fluid shows high density (hemoperitoneum: 35-60 HU). Liver metastases may coexist and are best evaluated in the portal venous phase.
Report Sentence
Progressive enhancement of solid tumor areas continues in the portal venous phase, but large necrotic-hemorrhagic areas remain non-enhancing in all phases; high-density free fluid consistent with hemoperitoneum is present in the peritoneal cavity.
On T1-weighted sequences, the tumor shows mixed signal intensity. Subacute intratumoral hemorrhage areas are characterized by marked T1 hyperintensity — methemoglobin accumulation is the cause of this hyperintensity. Solid tumor components are mildly hypointense or isointense relative to splenic parenchyma. Necrotic areas are T1 hypointense. Hemorrhage of different stages reflecting multiple bleeding episodes (acute: isointense, subacute: hyperintense, chronic: hypointense hemosiderin) may coexist within the same mass.
Report Sentence
Hyperintense foci indicating subacute hemorrhage are observed within the splenic mass on T1-weighted sequences, forming a mixed signal pattern with necrotic hypointense areas.
On T2-weighted sequences, the tumor shows markedly heterogeneous signal. Solid tumor components demonstrate intermediate-to-high T2 signal intensity. Necrotic and cystic degeneration areas are markedly T2 hyperintense. Chronic hemorrhage areas with hemosiderin deposition are T2 hypointense — these low-signal foci contribute to tumor heterogeneity. The 'bag-of-blood' appearance has been described: different signal characteristics of hemorrhage at various stages on T2 give the tumor fluid-fluid levels and a multicompartmental appearance.
Report Sentence
The splenic mass shows markedly heterogeneous signal on T2-weighted sequences, with necrotic hyperintense and hemosiderin-containing hypointense areas creating a 'bag-of-blood' appearance.
On diffusion-weighted imaging, the solid tumor components show markedly hyperintense signal at high b-values (b=800-1000), with restricted diffusion confirmed by low signal on ADC map (ADC <1.0 × 10⁻³ mm²/s). Necrotic-cystic areas may show T2 shine-through effect on DWI but have high ADC values (>1.5 × 10⁻³ mm²/s). Hemorrhagic areas may show signal loss on DWI due to susceptibility artifact.
Report Sentence
Marked restricted diffusion is observed in the solid components of the splenic mass on DWI with low ADC values, consistent with a highly cellular malignant tumor.
On B-mode ultrasonography, the spleen is markedly enlarged with heterogeneous echogenicity mass or multifocal nodules within the parenchyma. Solid components appear as mixed echogenicity (hypo-hyperechoic) areas. Necrotic areas are hypoechoic-anechoic, and hemorrhagic areas may be hyperechoic. The internal echo pattern is irregular and complex. In the event of splenic rupture, free fluid in the peritoneal cavity (which may contain echogenic particles — hemoperitoneum) is observed.
Report Sentence
On B-mode US, the spleen is markedly enlarged with a heterogeneous echogenicity complex mass within the parenchyma; necrotic hypoechoic and hemorrhagic hyperechoic areas coexist.
On color Doppler US, an irregular and chaotic vascular pattern is observed in the solid tumor components. High flow velocities and low resistive index (RI <0.5) indicate malignant neovascularity. Arterial pulsatility in the venous waveform may be seen due to arteriovenous shunts. No vascularity is present in necrotic areas. US evaluation should be performed cautiously due to rupture risk.
Report Sentence
Irregular chaotic vascular pattern and low resistive index indicating malignant neovascularity are observed in the solid components of the splenic mass on color Doppler examination.
Criteria
Diffusely infiltrates the splenic parenchyma without forming a distinct focal mass. Splenomegaly is prominent. CT/MR shows heterogeneous splenic enhancement with possible multiple millimetric nodules.
Distinct Features
No distinct focal mass present; splenomegaly is dominant. Spontaneous rupture risk is high as tumor spreads throughout parenchyma near the capsule. Diagnosis is often made on pathological examination after splenectomy.
Criteria
Presents with a dominant large mass (>5 cm) within the spleen. Hemorrhage and necrosis are prominent. CT/MR shows heterogeneously enhancing mass with satellite nodules.
Distinct Features
Large heterogeneous mass is readily identified on CT. Necrotic-hemorrhagic components are prominent. Satellite nodules indicate intrasplenic spread. T1 hyperintense hemorrhage areas on MRI are characteristic.
Criteria
Multiple nodules (typically 1-5 cm) are seen throughout the splenic parenchyma. Each nodule may show different size and enhancement pattern. Splenomegaly accompanies.
Distinct Features
Multiple nodules may be confused with lymphoma and metastasis. Distinguishing features: inter-nodular hemorrhage, T1 hyperintensity, and intense arterial enhancement. In metastasis, there is usually a known primary tumor history; in lymphoma, nodules are more homogeneous.
Distinguishing Feature
In lymphoma, splenic nodules are more homogeneous, hypovascularly enhancing, and hemorrhage is rare. In angiosarcoma, heterogeneous hypervascular enhancement, intratumoral hemorrhage (T1 hyperintensity), and spontaneous rupture are characteristic.
Distinguishing Feature
Metastases have a known primary malignancy history. Metastatic nodules generally enhance more uniformly, and hemorrhage showing T1 hyperintensity is rare. Angiosarcoma is a primary splenic tumor with dominant hemorrhage+hypervascularity.
Distinguishing Feature
In hemangioma, peripheral nodular enhancement and centripetal fill-in with late homogeneous enhancement is typical — a benign vascular pattern. In angiosarcoma, enhancement is irregular and aggressive, necrotic areas never fill in any phase, and spontaneous rupture risk exists.
Distinguishing Feature
Hemangioendothelioma is a lower-grade vascular tumor; it shows a more homogeneous structure, prominent hemorrhage-necrosis is rare, and clinical course is slower. Angiosarcoma is high-grade, aggressive, with extensive necrosis-hemorrhage, rapid progression, and poor prognosis.
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralSplenic angiosarcoma is an extremely aggressive tumor with most patients having metastases (liver, lung, bone) at diagnosis. Spontaneous splenic rupture requires emergent splenectomy. Biopsy is generally not performed — splenectomy is both diagnostic and therapeutic due to splenic rupture risk. Median survival is less than 6 months. Adjuvant chemotherapy (doxorubicin-based) may be administered but efficacy is limited. Multidisciplinary oncology follow-up is mandatory.
Splenic angiosarcoma is a highly aggressive tumor with poor prognosis (median survival <1 year). Spontaneous rupture requires emergent surgery. Treatment is splenectomy, but metastatic disease is common.