Surgical treatment of tumours of the sternum – 10 years’ experience

Introduction

Tumours of the sternum are rare. They can be primary, metastatic or arise from adjacent tissues. Histologically they can be malignant, benign or inflammatory.
Management depends mainly on their histological type, local aggressiveness and the possibility of chest wall reconstruction.
We describe our 10 years of experience in the treatment of this pathology.

Material and methods

We report on a series of 30 cases of sternal tumours treated in our institution between 2006 and 2015. There were 16 men, 14 women, average 54.4 years (range: 26–73). Most patients had the following symptoms: pain (22 cases), a palpable mass (all patients) and swelling (6 cases) in the sternoclavicular joint region.
Tumours were located in the sternoclavicular joint in 6 cases, in the manubrium in 7, in the body in 14 and in the xyphoid process in 2 cases. One patient had a large infiltration of the chest wall, and it was difficult to establish the location of the disease.
The histological type of tumour was determined by surgical biopsy or excision of the tumour. There were 18 benign, 10 malignant and 2 metastatic tumours (Tab. I).
The size of the tumour was determined by a chest computed tomography (CT) scan (Figs. 1 and 2). The size of the benign lesions was 1.8 cm to 4.9 cm and of the malignant lesions was 3.6 cm to 10.2 cm. All malignant tumours were located in the body of the sternum, metastatic in the manubrium, inflammatory in the sternoclavicular joints, and benign in different parts of the sternum.
Before surgery, pulmonary function tests were routinely used in all patients, and a metastatic work-up was undertaken to eliminate an extrathoracic metastatic lesion.
Surgical excision of the tumour was undertaken in 24 cases, surgical biopsy in 6.
Following general anaesthesia the sternal tumours located in the chest wall with at least a 4 cm margin were totally removed. For small resection direct closure was performed.
For the longer defects, regional musculocutaneous flaps were used for coverage of the polypropylene mesh. A prosthesis was sutured with 0-Prolene sutures to the edges of the resected chest wall. After whole body sternal resection, polypropylene/methyl methacrylate sandwiched mesh was used for closing the defect. In 1 case an omental flap was used as coverage mesh (Fig. 3). Microscopic evaluation of the margins by frozen section was not routinely performed due to wide resection. Subcutaneous drainage was not used at the mesh site. Pressure dressing was routinely used when there was no respiratory support postoperatively.

Results

The postoperative period was complicated in 1 patient (cardiac arrest and death). Average length of stay in hospital was 2–11 days (mean: 4.3).
The patients with malignancy were referred for radio and/or chemotherapy postoperatively. The first visit was in the 4 weeks postoperatively, and then patients were seen every 3 months in the first year, every 6 months in the second and subsequently every 12 months.
Local recurrence was observed after 2 years in 2 patients and lung metastases in 2 patients with chondrosarcoma. They needed further operations and lung metastasis excision.

Discussion

The incidence of sternal tumours has not been established. Malignant tumours represent 0.6–0.9% of all primary bone tumours [1–3]. Chondrosarcoma is the most common tumour of the sternum, followed by osteosarcoma, myeloma and malignant lymphoma. Benign sternal tumours according to the Mayo Clinic were found in 0.1% of all benign bone tumours [2].
Among benign chondromas, osteoblastoma and haemangioma have been described [4–6]. Two thirds of sternal tumours are metastatic or locally invasive. Most frequently, there is breast cancer invasion, lung or pleural malignancy invasion or rarely solitary metastasis from the kidney or thyroid [7, 8].
Clinical signs are not specific. Chest pain, palpable mass and signs of swelling are frequently found. Signs of inflammation were seen mainly in sternoclavicular regions.
A CT scan of the chest gives precise information about extension, pulmonary invasion or metastases and aids in the assessment of mediastinal lymph nodes.
The diagnosis was obtained by surgical biopsy. However, even surgical biopsies may be uncertain when the cortex of the sternum is not involved. For this reason most of our patients had surgical excision of the tumour (24 cases).
The causes of sternoclavicular joint pain and swelling were usually non-malignant, and moderate to severe degenerative changes were found [9]. In the manubrium we found 2 metastases (1 from a kidney, 1 from a thyroid). Distant solitary metastases of kidney or thyroid cancer to the sternum are very rare and associated with a poor prognosis [7, 8].
Most malignant tumours were located in the body of the sternum. Tumours in the xyphoid process were non-malignant and very easy to remove.
Whenever possible, surgery is the best therapeutic option for a sternal tumour. In some cases radiation and/or chemotherapy may be used pre- or postoperatively, especially in tumours with sensitivity to their treatment (Hodgkin or non-Hodgkin lymphoma, plasmocytoma) [10].
Wide resection and simultaneous reconstruction is essential for the surgical procedure. The resection margin has been discussed in the literature since the extent of resection is associated with radical resection [11]. Most suggest a 4–5 margin, or simply negativity in a frozen section without a specific distance was safe enough [12].
Many techniques have been described for the closure of the chest wall defect to minimize paradoxical movement and protect the mediastinal structures after sternal resection [11–14]. Autoplastic reconstruction is suggested for small defects, while alloplastic materials are suggested for larger defects.
Reconstruction with a skin flap, myocutaneous flaps, Marlex mesh, Gore-Tex dual mesh, methyl methacrylate sandwiched between Marlex mesh, allogenic sternal graft, autogenous rib graft, porous titanium mesh, and metallic bars was described [5, 11–14]. In our patients we used polypropylene mesh, and we obtained rigidity (when necessary) by using a methyl methacrylate sandwich.
After manubrium resection, a muscle flap is recommended and rigid reconstruction after lower sternal resection to protect the heart and stabilise the thorax [6]. Omental flaps are used for infected sternal wounds and filling residual cavities [12].
The role of chemotherapy and/or radiation in sternal tumours remained unclear. For tumours that appeared to be radio/chemosensitive (Hodgkin lymphoma, Ewing sarcoma, plasmocytoma) and patients who were at high risk of local recurrence or compromised margin a benefit from adjuvant treatment might be obtained.
Despite the adjuvant treatment our 4 patients with chondrosarcoma had local or metastatic recurrence.
The multidisciplinary management of primary malignant tumours of the sternum is worth further discussion.

Disclosure

Authors report no conflict of interest.

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