Intraosseous epithelioid haemangioendothelioma

A 60-year-old gentleman was referred via his GP for a chest x-ray for left lower chest wall pain. Initial chest radiograph demonstrated a small pulmonary nodule within the left mid-zone. Before any further investigations were performed a repeat chest x-ray was performed two months later for persisting chest wall pain. This again demonstrated a left mid-zone pulmonary nodule however at this stage an approximately 2cm expansile lytic focus was seen within the right scapula, which had not been reported on previous imaging. Margins were well defined and there was no periosteal reaction.

Patient proceeded to CT chest.

CT chest demonstrated multiple left-sided lung nodules and appearances within the left scapula revealed the lytic lesion to be lobulated, expansile, peripherally sclerotic, predominantly lucent with mineralised architecture centrally and cortical breach anteriorly. Additional lucent and peripherally sclerotic lesion was present within the left proximal humerus. No locally aggressive features however lesion was suspicious for further disease.

Myeloma screen and PSA were normal. CT abdomen and pelvis did not reveal any significant abnormality.

MRI of the right scapula demonstrated the expansile bone lesion without soft tissue mass or periosteal reaction. Signal was intermediate on T1 with heterogenous intermediate to high signal on fluid sensitive sequences, T2 and STIR. 

Given the indeterminate features, the lesion underwent CT guided biopsy which confirmed the lesion as epithelioid haemangioendothelioma.

Subsequent bone scintigraphy demonstrated increased uptake within the right scapular and proximal humeral lesions confirming metastatic disease.

Epithelioid haemangioendothelioma is a rare vascular tumour that commonly arises within lung, liver and superficial soft tissues [1]. Epithelioid haemangioendotheliomas have a prevalence of less than one in a million and presentation of the bone is an extremely rare occurrence compromising less than 1% of bone tumours [2,3].  

Epithelioid haemangioendothelioma was first described in 1982 and is considered a low to intermediate grade malignant vascular tumour. Intraosseous lesions are predominantly located within the tubular bones but can arise anywhere within the skeleton. It can be multifocal in up to 64%[4,5]. 

Case series consisting of 46 patients with an average follow-up of 46 months demonstrated a post-resection local recurrence rate of 13%, metastatic rate of 31% and a mortality rate of 13%[5]. 

The most common presentation is within the second decade of life [6]. It is usually non-specific in nature with bony pain or superficial tissue swelling. Rarely, they can present as a pathological fracture [7]. Examination is also non-specific may reveal a pale or red firm mass.

As well as Epithelioid haemangioendothelioma, there are other subtype of haemangioendotheliomas, namely kaposiform dapska tumour, spindle-cell, retiform and composite. They are vascular in nature and composed of epithelioid-appearing endothelial cells which are organised into cords and nests within myxoid or hyaline stroma[8]. The pathogenesis remains uncertain however recent cytogenetic studies demonstrate that the tumorigenesis is a result of gene mutations, which is useful in demonstrating that multifocal disease is a result from metastases, and not concurrent neoplastic proliferation [9].

They have a variable appearance at imaging depending on level of aggressiveness. Radiographically they are lytic in nature and may have a honeycomb appearance.  They may be bubbly in nature and can show bony expansion. In aggressive cases they may show permeative destruction [10]. Internal calcification or matrix, as is seen is this case, is considered very rare findings [11]. The presence of multifocal lesions throughout the skeleton or in one anatomic region can be a clue to indicate a disease is of vascular origin [12].

MR findings show inhomogeneous low T1 and inhomogeneous higher T2 signal. They will be diffusely enhancing and can have prominent peripheral vessels.

They will have a wide differential including plasmacytoma or giant cell tumour if unifocal, as metastases, brown tumours and multiple myeloma if multifocal. However given their non-specific appearances they require histology to confirm their diagnosis [13].

The multiple lung nodules were considered metastatic in nature. Repeat CT chest performed after a 4 month interval showed no interval change in appearances of the pulmonary nodules or bony lesions. Following sarcoma MDT and review by the regional oncology service patient was managed conservatively. Unfortunately, follow up CT studies demonstrated disease progression.

Epithelioid haemangioendothelioma of the bone is a rare entity and no standard treatment options have been proposed. Radical surgery is performed for resectable tumours, solitary or multiple. Radiofrequency ablation has also been used pre-operatively to reduce the extent of resection and improve aesthetics and need for amputations [14].

Learning points

• Epithelioid haemangioendothelioma is a rare low-intermediate grade malignant tumour that can arise in bone however more commonly arises in the lungs, liver and superficial soft tissues
• When osseous they usually arise in the long bones
• Variable course depending on aggressiveness, ranging from benign to low grade
• Non-specific presentation bony pain and or swelling
• Should be considered in differential for well-defined lytic lesions with sclerotic border
• Requires histology to confirm the diagnosis