Diagnostic Enigma: Spindle Cell Sarcoma of the Aorta Presenting as Pulmonary Embolism and Chronic Anaemia

Abstract

Primary aortic sarcoma is a rare and aggressive malignancy with only approximately 190 cases reported in the literature. While angiosarcoma and intimal sarcomas represent an estimated 67.7% of malignant aortic tumours, spindle cell sarcomas are even more exclusive, consisting of only 0.9% of malignant aortic tumours. Differentiated from other malignant aortic tumours, spindle cell sarcomas are of mesenchymal origin and usually express vimentin and osteopontin. Clinical presentations are variable and nonspecific, ranging from back pain, abdominal pain or elevated blood pressure, misleading to differentials like pulmonary emboli or aortic aneurysms such as in our case here. In this article, we discuss the finding of an extremely rare aortic sarcoma masquerading as a pulmonary embolism. The patient underwent surgical resection; however, the course was complicated by the development of brain metastases and intracranial haemorrhage. The literature is expanding regarding the evolution of adjuvant chemotherapy and radiation therapy in the treatment of these patients. The exact pathogenesis of spindle cell sarcomas is unknown but thought to be related to the MDM2-p53 pathway. The development of spindle cell sarcomas may be related to Li-Fraumeni syndrome, which should be on the differential for these patients. This case highlights the importance of identifying aortic sarcomas in patients who present with signs and symptoms of peripheral embolization as the diagnosis can be easily misconstrued for thrombus or aortic aneurysm, leading to a delay in proper and timely management. We herein emphasize that aortic sarcomas should be included in the clinician's working differential due to the poor prognosis and outcomes that these aggressive tumours carry.

Learning points: Malignant aortic tumours are rare and can present with a multitude of symptoms ranging from constitutional symptoms to abdominal discomfort to unexplained hypertension. Spindle cell sarcomas represent 1 of the least common malignant aortic tumours reported in the literature.Malignant aortic tumours have a poor prognosis, and of the various types of malignant aortic tumours, aortic sarcomas have a particularly poor prognosis with a 5-year survival rate of 8%.The exact pathophysiology of these malignancies is unknown but is thought to be related to the MDM2-p53 pathway and may be related to Li-Fraumeni syndrome.

Keywords: Li-Fraumeni syndrome; Primary aortic sarcoma; malignant aortic tumour; pulmonary embolism; spindle cell.

Figure 1

Large soft tissue mass (arrow) intricately associated with the ascending thoracic aorta, arising superior to the level of the aortic root and proximal aortic arch with 90% mass effect on the superior vena cava identified on magnetic resonance imaging of the chest. Coronal view (A) and sagittal view (B)

Figure 2

Biopsy of the periaortic mass demonstrated atypical spindle cells in intersecting fascicles with increased mitotic activity and large areas of necrosis, consistent with high-grade spindle and pleomorphic sarcoma. Tumour cells were negative for CDK4 and MDM2 expression. Ki67 staining showed an increased proliferation rate of 40–50%

Figure 3

Haemorrhagic metastasis with surrounding oedema and mass effect (causing right to left shift) on the right midbrain identified on head CT without contrast