Surgical exposure was obtained via a triangular incision running from behind the right ear, along the anterior axillary line and across the sternum. First, the brachial plexus was dissected, the phrenic and recurrent nerves identified and followed distally. The upper border of the tumour became visible at the upper thoracic aperture. The recurrent nerve was observed to run through the tumour capsule. Further preparation was carried out from the distal edge of the wound. The pectoralis major muscle was elevated and care was taken to preserve the vascular pedicle (thoracoacromial A.V.). It was further observed that the first intercostal space was invaded by the tumour. Subsequently a thoracic wall resection including a partial resection of the right clavicle, the right half of the sternum and the costal attachment of the first three ribs was performed uncovering the mediastinum. The vena cava was revealed and trachea dissected. In this area the tumour was in close proximity to the trachea displacing it to the left but without tracheal infiltration. Next, the carotic artery and the jugular vein were exposed.

The tumour, located in the right supraclavicular region/upper mediastinum, was found to surround both the subclavian and the internal and external jugular vein. Hence a resection of the subclavian vein proximal to its conjunction with the superior vena cava was required. The internal as well as the external jugular vein were incorporated into the tumour conglomerate (Fig. 3). The tumour was resected en bloc. A partial resection of the clavicle, partial resection of the sternum with removal of the brachiocephalic, sublcavian and right jugular vein and the recurrent nerve was necessary to obtain clear resection margins. The defect coverage was achieved by a pedicled myocutaneous pectoralis major island flap.

Within the surgical specimen multiple nodular polypoid tumour masses of soft consistence with diameters of up to 3.6 cm, immediately adjacent to vascular structures of the subclavian, internal jugular and brachiocephalic vein were present. The tumour with its intravascular and extravascular components comprised a total area of 7.6 × 8 × 3.3 cm. The largest intravascular tumour sprout extended close to the resection surface of the vessel.

The macroscopic appearance resembled an intravascular tumour originating from the subclavian vein with infiltration of extravascular structures.

Microscopically the spindle-shaped cells of this mesenchymal neoplasm originated from the media of the venous vessel wall (Fig. 4). The tumour cells formed various fascicles interwoven with other longitudinal cross sectional neighbouring fascicles (Fig. 5). The tumour cells were characterized by an eosinophilic cytoplasm and cigar shaped nuclei. The mitotic rate was 19/10 HPF (per high power field). Some foci of tumour necrosis were present.

The neoplasm derived from the media of the vessel wall, disrupted the existing vascular architecture and formed an intravascular tumour sprout.

Immunohistochemically the majority of tumour cells were positive for smooth muscle actin and desmin. A positive reaction for the proliferation marker Ki 67 was found in 25% of all tumour cells,

Thus confirming the diagnosis of an intravascular leiomyosarcoma (malignancy grading GII)

Postoperatively only mild signs of mixed venous and lymphatic stases of the upper extremity following the resection of the subclavian vein were observed due to the well established collateral blood flow (as seen in the preoperative angiogram). These symptoms could be positively influenced by elastic compression dressings and physical lymph drainage. Owing to the resection of the right recurrent nerve, right sided vocal cord palsy occurred. Logopaedic training was initiated. The patient recovered well and was discharged two weeks later. Both pre- and post-operatively no symptoms of pulmonary embolism were detected.

Unfortunately the patient declined the recommended radiation therapy.

After an initial 5 month of tumour free survival without evident signs of either local or systemic metastasis a tumour relapse was detected. At this stage the patient refused further treatment apart from a palliative chemotherapy.

The clinical picture of an upper venous stasis may be caused by a number of different malignancies such as lung cancer and lymphomas 12. In particular, intravascular neoplasm may lead to stasis of the blood flow through intraluminal obstruction 1314. Preoperative angiograms with the according filling defects, CT scans and MRI in conjunction with the clinical signs of vascular compression are useful tools in the diagnostic and operative planning of intravascular leiomyosarcoma. MRI scan can assist in differentiating an intravascular tumour growth form thrombosis. The former is represented as an homogenous tumour with an intermediate signal intensity on T1 – weighted imaging whereas a thrombus is of high signal intensity on T1 and T2 sequences 15. The presented case underlines the difficulty in the preoperative interpretation of the origin of an intravascular leiomyosarcoma with unusual localization and tumour progression extending over the normal vascular structures into the surrounding soft tissue lacking the clinical picture of venous stases.

Moreover CT scan and MRI will not in all cases allow for an exact image of the endovascular tumour component 14 as in this particular caseTumours of the venous vessel wall may present with an intraluminal growth pattern or may extent from the tunica media and infiltrate the surrounding soft tissue 9. Especially in thin veins extension into the perivascular soft tissue may occur early 2. Since vascular leiomyosarcoma are often composed of an intraluminal as well as extravascular tumour component 6 on biopsy diagnosis of a soft tissue leiomyosarcoma it is necessary to consider the rare possibility of a primary intravascular tumour growth which may influence the surgical strategy. Primary intravascular tumour growth may require careful preparation and resection of the venous course affected by the malignancy.

Such tumour localizations result in both pre- and postoperative pulmonary microthrombembolism as frequent complications particularly in tumours of the pulmonary artery 16.

Furthermore, pulmonary metastases as the preferred distant tumour manifestation must be considered in the oncological care and staging 11.

As a malignant mesenchymal tumour, leiomyosarcoma displays differentiation tendencies towards smooth muscle morphology. Hence, histologically spindle shaped cells with eosinophilic cytoplasm with muscular striation and cigar shaped rounded nuclei can be observed. The cytoplasm is rich in contractile fibers (proteins) such as actin, desmin as well as h-caldesmon.

The differential diagnosis includes the spectrum of spindle cell shaped neoplasm. Mesenchymal tumours, the benign and malignant tumours of the nerve sheaths myofibrolastic tumours (myofibromatosis, fibromatosis, myofibroblastic sarcoma), synovial sarcoma, fibrosarcoma and NOS (not otherwise specified) sarcoma have to be considered 17.

In addition to histomorphology using standard H&E staining immunohistochemical staining for smooth muscle markers facilitates the correct diagnosis. The intravascular leiomyomatosis is characterized by the proliferation of smooth muscle vascular structures of the uterus or its surrounding. Intimal sarcoma, malignant mesenchymal tumours of the large arteries which originate from the intimal layer of the vessel wall and present as fibroblastic or undifferentiated sarcoma 18 and the very rare intravascular angiosarcoma belong to the differential diagnosis of malignant intravascular tumours 19.

Complete surgical resection of the vessel segment is the therapy of choice. When an intravascular tumour origin is suspected, a ligation of the vessel far distant from the palpable tumour mass might be necessary due to considerable expansion of the intraluminal tumour sprouts 610.

Leiomyosarcomas of a vascular origin appear to be associated with a more aggressive tumour growth and poorer prognosis compared to respective tumours of the soft tissue 7. Incomplete tumour resection requires adjuvant radiation therapy. Tumour size and localization are of prognostic value 9.

Leiomyosarcomas of the inferior vena cava appear to have no adverse prognosis compared to other tumour localizations 20.

The intravascular growth of the sarcoma predisposes for hematogenic metastases 11. Hence pulmonary metastasis has to be considered in the oncological follow up.