Vascular tumor
For information on vascular anomalies, click here.
For information on benign vascular tumors, Click here.

# Overview
Vascular tumors are growths (benign or malignant) formed from blood vessels; for example, hemangioma, hemangioendothelioma, Kaposi sarcoma, angiosarcoma. International Society for the Study of Vascular Anomalies (ISSVA) has classified vascular tumors into three main categories depending on their clinical and histological behavior. Some lesions related clinically and/or histologically to vascular tumors have been described in provisionally unclassified vascular anomalies and related lesions.

# Classification
*congenital hemangioma (rapidly involuting type) and tufted angioma may be associated with thrombocytopenia and/or consumptive coagulopathy in some cases. Many experts consider tufted angioma and kaposiform hemangioendothelioma to be part of a spectrum rather than distinct entities
Adapted from International Society for the Study of Vascular Anomalies

# Benign vascular tumors
Benign vascular tumors, are benign growths formed from blood vessels; such as, hemangioma, hemangioendothelioma, Kaposi sarcoma. They exhibit a wide range of clinical manifestations, and may occur as isolated lesions or may occur as manifestation of multi-system syndromes and diseases. Their diagnosis and management depends on their clinical manifestations and coexistent anomalies. International Society for the Study of Vascular Anomalies (ISSVA) has classified these lesions into benign vascular tumors and related lesions.
For more information on benign vascular tumors, click here.

# Locally aggressive or borderline vascular tumors

## Kaposiform hemangioendothelioma
- Locally Aggressive tumor that originates on skin and occurs primarily in childhood. It is characterized by a single or multiple masses with following characteristics:
Deep reddish-purple color
Shiny, firm texture
Warm to the touch
Swollen and painful
- Deep reddish-purple color
- Shiny, firm texture
- Warm to the touch
- Swollen and painful
- May be complicated by Kasabach-Merritt phenomenon (KMP), characterized by consumption coagulopathy, thrombocytopenia, and hemolytic anemia. Typical features also include low fibrinogen and elevated d-dimers.
- Somatic activating GNA14 c.614A>T (p.Gln205Leu) mutations have been found in some KHE.
- Invasion of bone, retroperitoneum, and mediastinum has occured in some cases but no case of metastasis has been reported yet.
- Diagnostic work up may include blood tests, biopsy, contrast enhanced ultrasound and MRI or CT scan imaging.
- Treatment options include steroid, vincristine, interferon alpha, anti-platelet agents, sirolimus-containing therapies, and surgery.
For more information on Kaposiform hemangioendothelioma, click here.

## Retiform hemangioendothelioma
- First described in 1994 as a form of low grade angiosarcoma, retiform hemangioendothelioma commonly presents as a slow growing asymptomatic solitary nodule or plaque on distal extremities in 2nd-4th decade of life.
- It must be differentiated from angiosarcoma.
- High level of local recurrence but very low potential for metastasis.
- Diagnostic work up includes histopathological studies, that shows branching blood vessels are arranged in retiform pattern and MRI.
- Surgery is the treatment of choice, though 2/3rd cases recur.
- Adjuvant radiotherapy and adjuvant chemotherapy with recombinant interferon alpha and low dose cisplatin have also been reported in selected cases.

## Papillary intralymphatic angioendothelioma (PILA), Dabska tumor
- First described in 1969 by Dabska, this rare vascular neoplasm generally occurs in soft tissues but can also occur in bone. They usually appear as painless inflammatory irregular or nodular lesions below the skin surface.
- The distinctive feature on histopathology is the intravascular growth of well-differentiated endothelial cells presenting as a matchstick columnar configuration.
- They are locally aggressive but rarely metastasize. Locally recurrence after surgery is very common.
- Diagnostic studies may include histopathological studies, fine needle aspiration, MRI, and CT scan.
- Wide local excision is the treatment of choice. However any combination of steroids, chemotherapy, radiation therapy, and invasive procedures can be used to treat this tumor.

## Composite hemangioendothelioma
- A rare vascular neoplasms, characterized by an admixture of benign, low-grade malignant, and malignant vascular components, the ratio of each component can vary. They can occur in any age group.
- They occur predominantly as long-standing lesions in the dermis and subcutis of the extremities, but can also occur at other sites, including the oral cavity and in viscera such as kidney and spleen.
- It may recur locally and has the potential to metastasize. Recurrence was found to be in 8/10 cases in some studies. 
- Diagnostic work up must include biopsy because of heterogeneity of lesions and it must be differentiated from other vascular tumors.
- Surgical excision is the treatment of choice although some patients have been treated with interferons and electron beams.

## Pseudomyogenic hemangioendothelioma
- A locally aggressive tumor with endothelial differentiation that usually presents as multiple asymptomatic discontinuous lesions, often at extremities.
- SERPINE1-FOSB fusions are characteristic that result in over-expression of truncated form of FOSB. FBJ murine osteosarcoma viral oncogene homolog B, also known as Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog B, FOSB or FosB, is a protein that, in humans have been implicated as regulators of cell proliferation, differentiation, and transformation.
- It may mimic epithelioid sarcoma on histology but metastasis is very rare and prognosis is excellent.
- Diagnostic work up includes X-ray, MRI, CT scan and biopsy of the lesion.
- Excision is the typical treatment but chemotherapeutic agents including gemcitabine/taxane and mammalian target of rapamycin inhibitor, mTOR inhibitors such as sirolimus, VEGFR1-4/PDGFRA inhibitors such as telatinib have been used with success in various studies.

## Polymorphous hemangioendothelioma
- A rare vascular neoplasm, polymorphous hemangioendothelioma occurs in lymph nodes, but a few cases have been found in extra-nodal sites such as the mediastinum, spinal cord, and liver. It is a very rare cause of persistent lymphadenopathy. The data on natural history and clinical presentation is limited due to very few number of cases reported.
- Characterized by a polymorphous blend of solid, primitive vascular and angiomatous areas in varied proportions on microscopic examination.
- Diagnotic work up includes histopathological examination, MRI, and CT scan.
- Wide local excision has been used for treatment, with radiation therapy in case of recurrence.

## Kaposi sarcoma
- An AIDS-associated vascular malignancy that usually presents as mucocutaneous lesions but can also occur in viscera such as lungs. It can remain confined to skin but widespread visceral involvement may occur.
- There are three known variants:
One variant occurs spontaneously in Jewish and Italian males in Europe and the United States.
Another more aggressive variant is endemic in young children is endemic in Africa.
A third form occurs in about 0.04% of kidney transplant patients. There is also a high incidence in AIDS patients. HHV-8 is the suspected cause.
- One variant occurs spontaneously in Jewish and Italian males in Europe and the United States.
- Another more aggressive variant is endemic in young children is endemic in Africa.
- A third form occurs in about 0.04% of kidney transplant patients. There is also a high incidence in AIDS patients. HHV-8 is the suspected cause.
For more information on Kaposi sarcoma, Click here

# Malignant vascular tumors

## Angiosarcoma
- Angiosarcoma (AS) is malignancy that presents with a very heterogeneous distribution in the human body with aggressive clinical course, and may appear in multiple locations, from breast to liver or skin.
- Associated with MYC gene amplification and protein overexpression. Myc is a family of regulator genes and proto-oncogenes that code for transcription factors.
- Complete surgical excision and radiotherapy are the main treatments, with a minor role of chemotherapy.
For more information about angiosarcoma, click here.

## Epithelioid hemangioendothelioma
- A rare vascular tumor, described for the first time in 1975 by Dail and Liebow, that usually affects lung, liver and bones, although may occur many other sites in body including head and neck, breasts and lymph nodes.
- Usually asymptomatic but patient may present with respiratory symptoms, bone pains or other symptoms depending on the site of the tumor.
- Majority are characterized by a reciprocal t(1;3)(p36;q25) translocation. The t(1;3) results in fusion of a gene known as WWTR1 (or TAZ) to CAMTA1. These genes code for transcription factors.
- Imaging is crucial in forming both diagnosis and management plan. Recognition of the expression of vascular markers (Fli-1 and CD31 are endothelial-specific markers), and the microscopic evidence of vascular differentiation is of primary importance as well.
- Surgery has been used as primary treatment modality depending upon the location of the tumor, with radiotherapy being used in some cases.