Clinical History
An 81-year-old man presented with a 3-month history of progressive right posterior chest pain, with anterior irradiation. In the past two weeks there was significant worsening of pain. The patient referred anorexia, asthenia and irritative cough. No fever, dysphagia or other gastrointestinal/respiratory complaints were present. A CT scan was performed.
Imaging Findings
A large thoracic heterogeneous lobulated mass (with 7.5 cm maximum diameter) is visualized in the posterior mediastinum, extending to the right prevertebral region from the level of T3 to T6 thoracic vertebrae. The mass contacts and deviates the oesophagus and also contacts the trachea and its bifurcation. The mass is vascularized, with some areas of low attenuation. A small component of the mass is extending through the right T4-T5 intervertebral foramen into the spinal canal (with dumbbell shape) resulting in compression of the spinal cord to the left. No bone erosion of the vertebrae or ribs is identified.
Discussion
Mediastinal sarcomas are rare tumours that constitute approximately 2% of the mediastinal tumours. Mediastinal leiomyosarcomas account for about 11% of primary mediastinal sarcomas [1]. Most cases of leiomyosarcoma of the mediastinum arise from the wall of the oesophagus or great vessels and their clinical manifestation is usually related to oesophageal or vascular obstruction, respectively [2]. Leiomyosarcomas arising within the mediastinal soft tissue, without relation to the surrounding structures, are extremely rare. It is possible that such tumours arise from small vessels within the mediastinal soft tissue. Moran et al. [2] reported the largest series of this type of tumour, with 10 cases of leiomyosarcoma of the mediastinal soft tissues (3 in the anterior mediastinum; 7 in the posterior mediastinum). The mean age was 56 years and a female:male ratio of 3:7 was found.
In our case, the upper digestive endoscopy examination showed only external compression at the middle third of the oesophagus, with normal oesophageal mucosa. A histological CT guided core biopsy was performed, revealing the diagnosis of leiomyosarcoma. Surgery was not performed and the patient was referred for radiotherapy. In our case, the oesophagus is deviated by the mass, being difficult to evaluate the origin of the tumour as primary mediastinal or from the oesophageal wall with extrinsic growth. In oesophageal leiomyosarcomas, progressive dysphagia is almost always present as the main complaint (in 91.7% of the cases in a case series of 12 from Zhang et al. [3]). Our patient denied dysphagia, however, as the tumour was not removed we cannot exclude oesophageal wall origin.
A small component of the tumour was extending through the T4-T5 intervertebral foramen into the spinal canal with compression of the spinal cord. This is an extremely unusual feature for leiomyosarcoma tumours [4]. The tumour extension into the spinal canal leads to the differential diagnosis of the "dumbbell-shaped tumours". Dumbbell tumours are located in the paravertebral areas with an extension through the neural foramina into the spinal canal. Neurogenic neoplasms are usually associated with the dumbbell appearance and can be divided into the following groups: tumours of peripheral nerve origin, more common in adults (Schwannoma and Neurofibroma); tumours of the sympathetic ganglia origin, more common in childhood (Ganglioneuroma, Glanglioneuroblastoma and Neuroblastoma); tumours of the paraganglia origin (Paraganglioma). Nonneurogenic tumours, such as meningiomas and sarcomas and haematopoietic neoplams, like lymphoma and solid leukaemic infiltrates, are also included in the dumbbell tumours group [5].
Differential Diagnosis List
Mediastinal leiomyosarcoma
Neurogenic tumours
Lymphoma (NHD more common in the posterior mediastinum)
Final Diagnosis
Mediastinal leiomyosarcoma
