Epithelioid angiosarcoma of the spine: A case report of a rare bone tumor

Abstract

Epithelioid angiosarcoma (EA) is an extremely rare subtype of angiosarcoma, which is characterized by large cells with an epithelioid morphology. EA typically arises in deep soft tissues, including the adrenal gland, skin and thyroid, however, EA rarely arises in the spine. The current study presents a case of osteolytic lesions involving the fourth lumbar (L4) level of the spine. Preoperatively, the patient was misdiagnosed with metastatic carcinoma, however, a radiological examination detected the presence of osteolytic or destructive lesions in the vertebrae, which extended into the pedicles. Histopathological and immunohistochemical evaluations were performed on the tumor tissue obtained from a decompression specimen of the L4 vertebra. A bone lesion composed of sheet-like malignant cells exhibiting atypical epithelioid morphology with vascular formation was observed. The presence of anastomosing vascular channels lined by epithelioid endothelial cells also indicated that focal endothelial differentiation had occurred. In addition, immunohistochemistry assays revealed that the lesion was positive for the endothelial cell markers, CD31, CD34 and vimentin. The tumor was treated with decompression of the L4 vertebra, followed by posterior stabilization. The patient subsequently refused chemotherapy and radiotherapy but completed six months of follow-up. At the time of writing, the tumor remains under control and the patient is asymptomatic. This case highlights the difficulty of diagnosing EA, which requires careful pathological examination and immunophenotype labeling. At present, CD31 is the most sensitive marker for detecting EA.

Keywords: CD31; epithelioid angiosarcoma; factor VIII-related antigen; spine; vertebral tumor.

Figure 1

Magentic resonance imaging detected a cystic, destructive lesion in the L4 vertebra which exhibited a soft tissue component. (A) On T1-weighted sagittal image of the L4 vertebra, an intraosseous lesion with low signal intensity was observed and (B) on T2-weighted image, the lesion was slightly hyperintense. (C) Using short TI inversion-recovery imaging, the lesion exhibited high intensities. (D) On contrast-enhanced T1-weighted image, the lesion was homogeneously enhanced and was found to be compressing the adjacent spinal cord. L4, fourth lumbar.

Figure 2

Expansile osteolytic lesion of the L4 vertebra, including erosion of the cortex. (A) A radiograph of the spine revealed an osteolytic lesion of the L4 vertebra involving erosion of the cortex. (B) Computed tomography scans of the lumbar spine revealed the presence of an expansive, lytic and destructive lesion with a cortical attenuation in the L4 vertebra which included a soft tissue component. L4, fourth lumbar.

Figure 3

Proliferation of cells exhibiting epithelioid morphology, prominent nucleoli and abundant eosinophilic cytoplasm at magnifications of (A) ×40 and (B) ×100. Cells were accompanied by anastomosing vascular channels (stain, hematoxylin and eosin).

Figure 4

Expression of vimentin by tumor cells.

Figure 5

Expression of CD34 by tumor cells.

Figure 6

Expression of CD31 by tumor cells.