A 41-year-old man presented with a painful mass in the left leg. As an antecedent of interest, he had had a fracture of the left tibia and fibula 15 years before, which was treated surgically.
An X-ray, a CT scan and a MRI of the leg were performed and a US-guided biopsy (Fig. 3) to confirm the diagnosis. It was completed with a thoracoabdominal CT.
The radiograph and CT showed an osteosynthesis material in relation with spiroid fracture and an osteolytic lesion involving the anterior aspect of the tibia with cortical breakthrough and soft-tissue mass. No periosteal reaction or mineralised matrix were seen. The tumour presented calcified trabeculae in its interior with "soap bubble" appearance (Fig. 1 and 2).
MRI shows marked extension of the tumour to the soft tissues with lobed contours and a homogeneous signal, except for septa (Fig. 4). The tumour was biopsied and the results were: malignant neoplasic proliferation constituted by epithelial cells with immunohistochemical markers compatible with epithelioid hemangioendothelioma (Fig. 5). It was completed with a thoracoabdominal CT that showed another similar lesion in the left iliac bone (Fig. 6).
Malignant vascular tumours of the bone are rare, <1% of primary malignant bone tumours.
The epithelioid haemangioendothelioma (EHE) is a vascular tumour of intermediate-grade malignancy between haemangioma and angiosarcoma in terms of frequent local recurrences and metastatic potential [1, 2]. Weiss et al. described it first in 1982 as a vascular neoplasm of both bone and soft tissue [3]. In bones, EHE is located in metadiaphyseal, or less commonly, epiphyseal region of the lower extremities [2, 3, 4]. It can occur at almost any age (especially in the 2-3nd decade) with a slight male predominance [4]. Generally, patients complain of pain and swelling in the affected area. In 50% of cases multifocal disease is seen (multiple lesions in a single bone or multiple bone involvement).
Radiography typically reveals a cortical or medular expansive lytic lesion without matrix mineralisation. Calcification is infrequent, and periosteal reaction is rare in the absence of pathologic fracture. Cortical disruption, soft tissues and joint invasion can be present. [2] The "soap bubble" appearance has been described [5].
In MRI, EH has low to intermediate signal on T1-weighted images and high signal on T2-weighted-images with homogeneous enhancement after the injection of gadolinium [2].
The first diagnoses were adamantinoma and osteofibrous dysplasia. Soft tissue mass didn't allow us to rule out malignancy, and another similar lesion led us to consider metastasis and myeloma in a patient older than 40 years of age.
Although, before the multiplicity of bone lesions, absence of periosteal reaction and soft tissue mass the radiologist must include vascular tumours in their diagnoses. It is essential to suspect a vascular tumour, so that the pathologist can include vascular specific markers of endothelial cells (CD31, CD34, factor-VIII). [5]
It is important to know the 4th edition of the World Classification of Tumors of Bones and Soft Tissues of the WHO (2013). It includes genetic characterisation of EHE (for example, has been reported that YAP1-TFE3 translocation defines a subset which tend to affect younger adults and t(1;3)(p36;q23–25) is present in EHE at all anatomical sites) and proposes risk stratification according to size and mitotic activity [6].
EHE has a variable clinical course, usually prolonged. In some publications, the multifocal disease was thought to have a better prognosis. However, in the largest series, the overall survival for solitary disease was reported as 89% compared with 50% in multifocal disease.
Complete surgical excision is the treatment of choice. Others: preoperative embolisation, radiofrequency ablation and radiotherapy (alone or in conjunction with surgery). [2, 3]
Multifocal epithelioid hemangioendothelioma.
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Based on the patient’s history of left lower leg fracture fixation (visible intramedullary nail and fixation plate), on X-ray plain films and CT reconstruction images, multiple lytic lesions can be observed in the cortex and medullary cavity of the mid-distal tibia. They have relatively irregular margins, with partial cortical expansion. A “soap-bubble-like” appearance is noted in some areas. Although there is partial cortical destruction, no significant extensive periosteal reaction is evident. On MRI, T1-weighted images show predominantly medium to low signal intensity, T2-weighted images show high signal intensity, and the lesions are markedly enhanced after contrast administration, suggesting rich blood supply. In the adjacent soft tissue, a local mass can be observed, indicating certain soft tissue involvement.
Taking into account the patient’s age, clinical presentation of left lower leg pain and swelling, and the radiological findings of lytic and vascular characteristics, the following are considered as key differential diagnoses:
Combining the imaging characteristics (multiple lytic lesions with marked enhancement, lacking significant periosteal reaction, with local soft tissue masses) and pathology results indicating positivity for endothelial markers (CD31, CD34, etc.), the most likely diagnosis is “Epithelioid Hemangioendothelioma (EHE)”. This is a moderately malignant vascular tumor that shows local aggressiveness and potential for metastasis. Further confirmation of lesion extent and treatment strategy requires correlation with clinical symptoms, laboratory testing, and follow-up imaging.
The core management strategy, based on the current diagnosis and patient’s condition, involves surgical excision or lesion clearance, with additional local treatments considered if needed. Recommendations are as follows:
This report is based solely on the patient’s current medical history and radiological data, serving as a reference and not as a substitute for in-person consultations or licensed medical advice. Specific treatment plans require integration of clinical examinations, histopathological findings, and the attending physician’s assessment. Please consult a medical professional promptly if any doubts or changes in symptoms arise.
Multifocal epithelioid hemangioendothelioma.
