Primary malignant hemangioendothelioma of bone, also known as vascular fleshy tumor or endothelial fleshy tumor, is extremely rare. It was first reported by Kokodny in 1926, and by 1971, only about 100 cases had been documented in foreign literature, with few reports in China. Huvos defined it as "a tumor characterized by irregular but anastomosing vascular channels lined by one or more layers of atypical endothelial cells, exhibiting anaplastic and immature features." Spjut described it as "a rare malignant tumor originating from the vascular system cells of bone or their precursor cells, with endothelial cells showing obvious neoplastic features and a tendency to form tortuous, anastomosing blood vessels." This disease accounts for 0.1%–0.4% of all bone tumors, 0.5%–1% of malignant bone tumors, and 4.2% of primary spinal tumors. It is more common in males than females, with 70% of cases occurring between the ages of 10 and 40. The condition is usually solitary but occasionally multifocal. The long bones of the extremities are the most frequently affected sites, while spinal involvement is rare, primarily occurring in the thoracic, lumbar, and sacral regions, with only occasional case reports in the cervical spine. The tumor is composed of vascular endothelial cells or mesenchymal cells differentiating toward endothelial cells. It is highly malignant, grows rapidly, and often leads to early pulmonary metastasis.

bubble_chart Pathological Changes

The tumor appears dark red with no obvious capsule, has a tough texture, and is highly vascular. Microscopically, it is characterized by numerous irregular, anastomosing vascular channels. These are often lined by a single or multiple layers of atypical immature cells, accompanied by poorly differentiated or anaplastic tissue masses. The endothelial cells may form buds, giving the tumor a papillary appearance. There is a marked proliferation of capillaries with a tendency to anastomose with each other.

bubble_chart Clinical Manifestations

A fleshy tumor occurring in the cervical spine vessels, with patients primarily presenting symptoms of radicular pain and spinal cord compression, such as pain in the upper limbs, neck, back, and numbness in the fingers.

X-ray findings are often nonspecific, primarily showing osteolytic changes that may be confined to the cancellous bone or medullary cavity, or involve both cancellous and cortical bone simultaneously. The destruction areas appear as single or multiple radiolucent zones with moth-eaten or patchy patterns and indistinct borders. There is no reactive new bone formation, and periosteal reaction is rare. In highly malignant cases, the tumor lacks trabecular bone, has unclear margins, may penetrate the cortical bone, and invade surrounding soft tissues.

bubble_chart Treatment Measures

Radiation therapy is commonly used and is effective for early-stage, low-grade malignancies. Surgical treatment is suitable for cases with significant spinal cord compression requiring decompression, as well as for lesions located in the vertebral appendages that are easily resectable. Postoperative radiotherapy should still be administered.

This disease has a high degree of malignancy and often leads to early lung metastasis, generally resulting in a poor prognosis. In a minority of cases, the disease progresses slowly, and patients may survive for several years after surgery.