Clinical History
8-year-old boy presented with history of facial puffiness and gradually progressive breathlessness for two weeks. On examination, the child was tachypnoeic and distended superficial veins were seen over the temple and neck region. On percussion, a dull note was obtained on the right side.
Imaging Findings
Massive right-sided pleural effusion with tracheomediastinal shift to the left was seen on chest radiograph. Ultrasound revealed a heterogeneous predominantly iso to mildly hyperechoic lesion with minimal internal vascularity in close proximity to cardia and the great vessels.
On computed tomography, a fairly-defined, relatively hypodense mass lesion was seen in the anterior and superior mediastinum extending from T1 to T7 vertebra causing compression of left subclavian, common carotid, right innominate arteries, superior vena cava and oesophagus, trachea, right and left main bronchus with no bony erosion. The lesion showed relatively homogeneous enhancement on contrast administration with non-enhancing necrotic areas within.
Screening MRI of the thorax showed that the lesion was T1 iso-hypo, iso to hyperintense on HASTE sequences.
Discussion
The superior vena cava is the major venous drainage system for blood returning from upper extremities, head and neck. Superior vena cava syndrome (SVCS) is a condition which occurs when there is predominant major vessel compression in the superior mediastinum. It is also called superior mediastinal syndrome when there is compressive involvement of trachea, oesophagus and other associated structures. [1]
In adults, malignant tumours such as lung cancer, lymphoma and metastatic tumours are responsible for the majority of SVCS cases.
In the paediatric age group, SVCS is rare but serious. Malignant lymphoma is one of the most common causes of SVCS. Germ cell tumours can also cause SVCS in the paediatric age group. [2]
Thrombosis due to central venous catheters, aortic aneurysms, heart surgery are the other causes of SVCS in children.
Dyspnoea, coughing and swelling of the face, neck, upper body and arms are commonly encountered symptoms in SVCS. Hoarseness, chest pain, dysphagia and haemoptysis may also occur. Prominent neck or chest veins, rapid breathing, cyanosis, Horner’s syndrome and a paralysed vocal cord may also be present. [3]
Chest radiography may pick up associated indirect findings like pleural effusion, but is not adequate to identify the cause.
Ultrasound helps in identifying thrombosis in accessible veins and less frequently in visualising the lesion.
MDCT with contrast is useful in localising the site of the lesion, extent and characterising the lesion. It is fast, less expensive and bony changes can be studied well. On CT, lymphomas generally appear hypodense on plain films, showing homogeneous enhancement on contrast administration. Both Hodgkin and non-Hodgkin lymphomas can cause SVCS. [4]
MRI has the ability to image in several planes of view with excellent soft tissue characterisation and can directly visualise blood flow using contrast agents with better safety profile. However, increased scanning time, respiratory artefacts and cost are the disadvantages. MRI picks up chest wall invasion and neurovascular involvement more accurately in malignant mediastinal tumours.
Head end elevation, oxygen inhalation and diuretics are helpful supportive measures in patients of SVCS. Steroids provide symptomatic relief by decreasing oedema and tumour burden in malignant causes. Paediatric patients with malignancy as a source of SVCS, radiation and chemotherapy may be the initial course of treatment. Surgery may be necessary when medical or interventional treatments fail.
A definitive histological diagnosis is preferable before going for treatment. In the present case, image guided biopsy revealed tumour of small blue round cell origin consistent with non-Hodgkin lymphoma. The patient improved symptomatically after administration of intravenous dexamethasone and later underwent chemoradiation.
Differential Diagnosis List
Superior vena cava syndrome due to lymphoma
Superior vena cava syndrome due to lymphoma
Superior vena cava syndrome due to germ cell tumour
Final Diagnosis
Superior vena cava syndrome due to lymphoma
