CT is usually performed in cases of abdominal angiosarcoma (liver, spleen, ovarian, gastrointestinal) and for staging and follow-up of metastatic cases. [5]
Some non-specific findings can be observed on CT like low attenuation lesions, heterogeneous enhancement (there can be necrotic and fibrotic intralesional zones), irregular margins or calcifications in some cases.
Biopsy (guided by CT or US) is performed for diagnostic confirmation. A punch biopsy can be sufficient in skin and superficial cases. A percutaneous biopsy is performed for deep lesions (in our center we use a 14-G needle for soft tissue lesions with four or five cores taken and 16-G core needle for liver and splenic cases with one or two cores drawn).
Ultrasound has a limited role in the diagnostic process, although can be useful in cases of visceral angiosarcoma like liver or splenic angiosarcoma.
MRI is the preferred imaging technique for soft tissue and bone angiosarcoma [5] (our protocol includes T1 and T2 weighted sequences, STIR, DWI/ADC and T1 post-contrast sequences).
MRI can also be useful in abdominal solid organ angiosarcoma, especially in challenging cases like liver angiosarcoma (differential diagnosis with vascular lesions can be difficult without biopsy confirmation).
On RM we can characterize the tumor’s heterogeneous components with different sequences:
On T1 weighted images hemorrhage foci can be seen. On T2-weighted images we can see a high intralesional signal. Post-contrast sequences can show heterogeneous enhancement. Low ADC values are usually seen.
We can review the different locations of primary and metastatic angiosarcoma:
Skin:
Cutaneous angiosarcoma is the most frequent form of the tumor with head and neck being the most common location (up to 60% of cases [2]).
The typical findings one can encounter on MRI (imaging modality of choice in these cases) is hyperintensity of the lesion on T2-weighted images with hypointensity of high-flow serpentine intralesional vessels. Heterogeneous enhancement after contrast can also be seen. Fig 1: MRI T1 and T2 weighted images and ADC in axial plane of a cutaneous... Fig 2: MRI T2 weighted image and ADC in axial plane of a cutaneous angiosarcoma with... Fig 3: MRI T2 weighted images in axial and coronal plane of a eyelid angiosarcoma.
On CT isodense lesions with heterogeneous enhancement can be found. Fig 4: CT Axial image of a scalp angiosarcoma with skin thickening. Fig 5: CT Axial image of a heterogeneous large scalp angiosarcoma.
Hemangioblastoma, Merkel cell carcinoma and Kaposi sarcoma are the main entities in the differential diagnosis of cutaneous angiosarcoma, and punch biopsy is usually performed to obtain a definitive diagnosis.
Soft tissue:
Soft tissue angiosarcoma can be located at deeper subcutaneous tissues, soft tissues of the upper and lower extremities and the abdominal and chest wall.
On CT large solid lesions with heterogeneous enhancement are found in these different locations. Fig 6: CT Axial plane of a retroperitoneal large angiosarcoma with pleural...
MRI shows high signal on T2 weighted images with hyperintensity zones on T1 weighted images. Hypointensity of high-flow serpentine intralesional vessels can also be found. Heterogeneous enhancement after contrast is usually seen, with areas of necrosis. [fig] 7 [/fig]
Hemangioma, Kaposi sarcoma and other sarcomas have to be considered in the differential diagnosis.
Liver:
Hepatic angiosarcoma is the most common malignant mesenchymal tumor of the liver. [6]
In liver lesions (primary or metastasis) we can see different patterns of presentation: single mass, mass with nodules, nodules or diffuse infiltration [5].
On CT we can find hypodense nodular lesions with hyperdense intralesional foci in unenhanced studies. Heterogeneous progressive enhancement on the delayed CT phase without washout can also be found. In certain large masses zones of central necrosis can be seen.
Fig 8: Abdominal CT portal phase in axial and coronal plane that shows a large hepatic... Fig 9: Abdominal CT arterial phase showing a hepatic nodular low attenuation lesion...
MRI can help in cases of small lesions, which are hyperintense in T2 weighted images with heterogeneous contrast enhancement. ADC values can vary owing to the heterogeneity of these tumors. [7]
Fig 10: Hepatic MRI T2 weighted images where we can observe multiple hepatic... Fig 11: Hepatic MRI T1 C+ weighted image and DWI image that shows the heterogeneous...
There is a difficult differential diagnosis with hemangioma: Angiosarcoma doesn’t fill-in centrally in delayed phases, but in the other hand hemangiomas show complete enhancement. Angiosarcoma enhancement is also lower than the aorta. [8]
In liver lesions there is also a risk of hemorrhage that can be fatal, especially in cases of massive dissemination. Fig 12: Abdominal CT portal phase (left and lower right) and arterial phase (upper...
Spleen:
Splenic lesions show different patterns: Diffuse infiltration with splenomegaly, a large mass, various nodular lesions or ill-defined lesions with hemoperitoneum. [9]
CT and MRI findings are similar to those of liver angiosarcoma. Fig 13: Abdominal CT arterial phase that shows a large splenic angiosarcoma with... Fig 14: Abdominal CT portal phase that shows a large splenic angiosarcoma with necrotic...
Other vascular lesions (hemangioma, hemangiopericytoma,) should be included in the differential diagnosis.
Spontaneous rupture of the spleen is a relatively common complication which can be life-threatening, and can be the initial form of tumor presentation. Fig 15: Abdominal CT arterial and portal phase that shows a splenic rupture with...
Breast:
Breast angiosarcoma can be primary (usually young patients) or secondary (in cases of local radiotherapy) and in a majority of cases presents with a palpable mass. [1]
On mammography an ill-defined mass can be found in primary cases, but on the other hand secondary lesions present with a similar appearance to skin/soft tissue angiosarcoma. On ultrasound heterogeneous lesions are found, predominantly hypoechoic. MRI shows heterogeneous and rapid enhancement after contrast with rapid or persistent washout. Fig 16: Mammography craneocaudal view that shows a large ill-defined mass which was... Fig 17: Ultrasound image of a breast large primary heterogeneous angiosarcoma with... Fig 18: MRI T2 weighted image of a breast large primary heterogeneous angiosarcoma with... Fig 19: MRI ADC image of the same case on which we can see the low ADC values that...
Ovarian:
Although relatively rare, primary and metastatic angiosarcoma can also be found in ovaries. Fig 20: Pelvic CT venous phase that shows an adnexal lesion with intense peripheral...
Imaging findings are similar to other angiosarcoma visceral lesions and final diagnosis will be found usually post-surgery.
Bone:
In bone lesions there is difficulty in distinguish histologically between angiosarcoma and hemangioendothelioma. [10]
Angiosarcoma usually presents as lytic lesions with cortical erosion and soft tissue tumor extension. [11] Fig 21: Pelvic CT scan on which a large lytic bone lesion can be seen located in the... Fig 22: Pelvic CT scan that shows two well defined bone lytic lesions on the left iliac... Fig 23: Shoulder MRI T2 and T1 weighted images where we can see a large humeral...
It can be very challenging to differentiate between angiosarcoma, haemangiopericytoma and hemangioendothelioma.
Adrenal:
Adrenal primary angiosarcoma is rare, with metastases more frequent. They share image findings with other visceral lesions. Pheochromocytoma should be considered in the differential diagnosis. Fig 24: Abdominal CT arterial phase that shows an adrenal lesion (an adrenal...
Heart:
Heart is a rare location of angiosarcoma, being found predominantly in the right auricle. [12] Fig 25: Chest CT portal phase in axial and coronal plane that shows an intracavitary...
Brain:
Brain primary angiosarcoma is very rare, with image findings non-conclusive. We encountered a case of primary brain angiosarcoma in a patient in which glioma was suspected. Fig 26: Brain MRI T2, DWI, and T1 C+ weighted images on which a large lesion located in...
Metastatic locations:
The following are locations where primary angiosarcoma is rare and almost all cases are metastases. Other locations already discussed (liver, bone and soft tissue) also have a high proportion of metastatic lesions.
Lung:
Pulmonary angiosarcoma metastases most frequent appearance is solid nodules but can also present as thin-walled cysts or both.
Fig 27: Lung CT image where we can see a solitary nodule in the RLL which was suspected... Fig 28: Lung CT image of the pulmonary apex where we can see bilateral solid nodules...
Hemorrhagic changes can also be seen, like ground-glass areas surrounding nodular lesions, diffuse infiltrates or air-fluid levels. [13]
Peritoneal dissemination:
Abdominal angiosarcoma can present with peritoneal dissemination (in some cases associated with spontaneous hemoperitoneum). Fig 29: Abdominal CT arterial phase showing peritoneal hypervascular lesions with...
Kidney:
We have encountered some cases of kidney angiosarcoma metastases in patients with abdominal primary angiosarcoma. These lesions share the imaging findings with other abdominal lesions. Fig 30: MRI T2 and T1 C+ weighted images of bilateral renal focal lesions hypointense...
