Composite hemangioendothelioma

Composite haemangioendotheliomas are locally aggressive and rarely metastasising vascular tumours consisting of different and histologically distinct elements.

Epidemiology

Composite haemangioendotheliomas are very rare and mostly seen in adults. Women are slightly more commonly affected ^1,2.

Diagnosis

The diagnosis of composite haemangioendothelioma is established histologically ¹.

Diagnostic criteria

The diagnostic criterion according to the WHO classification of soft tissue and bone tumours (5^th edition)¹:

• presence of two or more morphologically distinct tumour components (usually similar to haemangioendothelioma and epithelioid haemangioendothelioma)
• at least two additional endothelial tumour elements in cases originating from pre-existing vascular or lymphatic malformations
• conventional angiosarcoma needs to be excluded clinically and morphologically if there are foci resembling high-grade angiosarcoma

Clinical presentation

The typical complaint is a lump with a reddish to purple-to-purple appearance which has been there for a long time ¹.

Associations

Composite haemangioendotheliomas are seen in patients with lymphoedema ¹. 

Pathology

Composite haemangioendotheliomas are formed by at least two histologically different vascular tumour components. These parts often resemble retiform or epithelioid haemangioendotheliomas ¹.

Aetiology

Chronic lymphoedema and irradiation are thought to have a role in the aetiology ¹.

Subtypes

Neuroendocrine composite haemangioendothelioma is the only subtype.

Location

Composite haemangioendotheliomas most frequently affect the skin and subcutaneous tissues of the distal extremities or the head and neck area but have been also found in other sites ^1,2. 

Macroscopic appearance

Macroscopically composite haemangioendotheliomas are nodular infiltrative ill-defined lesions ^1,2. 

Microscopic appearance

The microscopic spectrum of composite haemangioendotheliomas consists of a composition of different morphological vascular components and areas including the following ^1,2:

• epithelioid haemangioendothelioma
• retiform haemangioendothelioma
• spindle-cell haemangioma
• angiosarcoma-like
• lymphangioma 
• angiomatosis
• cavernous haemangioma 

Neuroendocrine composite haemangioendotheliomas are typically composed of epithelioid and retiform haemangioendothelioma-like parts with a nest-like appearance ¹.

Immunophenotype

Immunohistochemistry stains usually express CD31, ERG and FLI1 and can be positive CD34 and D2-40 ¹.

Genetics

Fusions of the PTBP1-MAML2 and EPC1-PCH2 genes have been observed in neuroendocrine composite haemangioendotheliomas ¹.

Radiographic features

MRI

Composite haemangioendotheliomas are vascular lesions with a lobulated and heterogeneous appearance ^2-4. 

Signal characteristics

• T1: low to intermediate signal intensity
• T2: high signal intensity
• T2FS/STIR: high signal
• T1 C+ (Gd): avid enhancement 

Radiology report

The radiological report should include a description of the following features:

• form, location and size
• tumour margins
• relation to the muscular fascia
• relationship to bones, tendons and joints
• relationship to local nerves and vessels

Treatment and prognosis

Due to the rarity of the tumours, there is no clear management strategy as yet. Treatment usually consists of surgical excision. Local recurrence is common and can happen multiple times. Lymph node metastases can occur. Distant metastases are seen in neuroendocrine composite haemangioendotheliomas, which are more aggressive ¹.

History and etymology

Composite haemangioendotheliomas were first described by an international group around the South African pathologist Simon J. Nayler in 2000 by SJ Nayler ⁵.

Differential diagnosis

The differential diagnosis of composite haemangioendotheliomas consists of the following:

• retiform haemangioendothelioma
• epithelioid haemangioendothelioma
• Dabska tumour
• Kaposiform haemangioendothelioma
• Kaposi sarcoma
• angiosarcoma