Unilateral superior vena cava syndromeUD Desai, JM Joshi
Department of Pulmonary Medicine, Topiwala National Medical College and BYL Nair Charitable Hospital, Mumbai, Maharashtra, India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0022-3859.143966
Source of Support: None, Conflict of Interest: None
An elderly man presented with clinical features of superior vena cava (SVC) syndrome restricted to the right side. Detailed evaluation suggested the diagnosis of unilateral SVC syndrome due to adenocarcinoma (presumably) from lung. With this case, we discuss the clinical presentation and causes of this rare clinical entity. Also, unilateral signs of SVC syndrome warrant a thorough clinical evaluation as it can be a presenting feature of a spectrum of diseases ranging from benign to malignant etiologies.
Keywords: Innominate vein obstruction, Pemberton′s sign, SVC syndrome
Superior vena cava (SVC) syndrome encompasses a constellation of symptoms and signs resulting from obstruction of the SVC. However, it's unilateral presentation, unilateral SVC syndrome, is rare and caused by selective obstruction of the innominate (brachiocephalic) vein.
A 77-year-old nonsmoker man was referred to the pulmonary medicine outpatient department in view of exertional breathlessness, dry cough, right facial swelling, right neck and supraclavicular fullness and dilated veins on the right anterior chest wall since 1 month. He had comorbities in the form of systemic hypertension and ischemic heart disease. He was operated for inguinal hernia repair 10 years ago and underwent coronary angiography with percutaneous coronary angioplasty 5 months ago. General examination revealed right neck fullness with multiple enlarged firm right level three, four, five and left level five lymph nodes. Systemic examination was normal except for the presence of multiple dilated veins with flow from above downwards on the right chest wall anteriorly [Figure 1]. His chest X-ray postero-anterior and lateral view showed mediastinal widening on X-ray [Figure 2]a and b.
What is the provisional diagnosis?
Unilateral SVC syndrome with mediastinal and cervical lymphadenopathy.
Case details (continued)
The routine hematological and biochemical blood investigations were normal. In view of the mediastinal widening he was evaluated with contrast-enhanced computed tomography of thorax. It showed a well-defined nodular enhancing lesion of 2.0 × 1.9 cm with spiculated margins in the medial segment of the right middle lobe crossing the minor fissure and extending into the right upper lobe with small nodules in the left upper lobe and the right lower lobe. A right supraclavicular lymph node mass was noted causing infiltration and total occlusion of the right internal jugular vein, right brachiocephalic/ innominate vein and partial obstruction of SVC [Figure 3] and [Figure 4]. In addition, there was pre-paratracheal, subcarinal, prevascular, right hilar and bilateral cervical lymphadenopathy. The fluorodeoxyglucose positron emission tomography (FDG-PET) scan showed metabolically active disease in the right middle lobe mass lesion (standard uptake value maximum 6.29) and right mediastinal nodal mass lesion with loss of fat planes between this mass and the SVC.
What is SVC syndrome?
SVC syndrome encompasses a constellation of symptoms and signs resulting from obstruction of the SVC.  William Hunter first described it in 1757 in a case of syphilitic aortic aneurysm. SVC syndrome is a clinical diagnosis. The symptoms can have acute, subacute or chronic duration. The most common symptoms of facial and neck swelling aggravating on lying down are related to the venous congestion and elevated upper venous pressures. These may be visually distressing and draw patient attention but are alarming and require urgent intervention if associated with symptoms suggesting airway compromise (i.e., dyspnea, orthopnea, cough, stridor, hoarseness) or cerebral edema (i.e., head fullness, headache, nausea, lightheadedness, syncope, distorted vision, altered mental status).  Hence, the rapidity of progression of symptoms, presence of airway compromise and neurological symptoms are important in triaging the patient for detailed evaluation for etiology versus an urgent intervention.
The clinical signs include dilated chest, neck and abdominal veins, facial and neck edema, plethora, conjunctival suffusion. The classical Pemberton's sign demonstrated by the Pemberton maneuver (achieved by having the patient elevate both arms until they touch the sides of the face) leading to facial congestion and cyanosis, as well as respiratory distress after approximately 1 minute may be positive in few cases of SVC syndrome.  Cyanosis, mental status changes, stridor, papilledema, stupor, coma are poor prognostic signs. It is worthy to note that clinical signs help in identifying the level of SVC obstruction. Pre-azygous or supra-azygous SVC obstruction results in venous distension and edema of the face, neck, and upper extremities. Post-azygous or infra-azygous obstruction results in not only the symptoms and signs of pre-azygous disease, but also dilation of the veins over the abdomen due to retrograde flow through the azygous vein via collaterals to the inferior vena cava.
Case details (continued)
Fine-needle aspiration cytology of the right and left cervical lymphnodes demonstrated large pleomorphic cells in sheets and clusters with abnormal nucleo-cytoplasmic ratio, hyperchromatic nuclei with prominent macronucleoli suggestive of metastasis from high grade epithelial neoplasm favoring adenocarcinoma. After being counseled about the malignant nature of disease, metastasis, inoperable advanced stage of malignancy and limited therapeutic options, the patient and relatives chose not to pursue further treatment. Due to this the computed tomography-guided biopsy of the primary lung nodule, bronchoscopic evaluation was not possible and further management was not pursued.
Final diagnosis: Unilateral SVC syndrome due to right supraclavicular lymph node mass causing occlusion-infiltration of right innominate (brachiocephalic) and right internal jugular vein in a case of right middle lobe lung nodule with cervical and mediastinal lymphadenopathy due to adenocarcinoma.
What is Unilateral SVC syndrome?
Unilateral SVC syndrome was first described by Forman et al. in 1980 with clinical similarity to SVC syndrome however with unilateral clinical findings  caused due to selective obstruction of the innominate (brachiocephalic) vein. In our case the right supraclavicular lymphnode mass caused extra-luminal occlusion with infiltration of the right innominate (brachiocephalic) vein and right internal jugular vein. Thus the venous drainage of the right face and neck was impaired. The left innominate (brachiocephalic) vein and left internal jugular vein were patent with normal venous drainage from the left face and neck. As the SVC was only partial obstructed due to tumor thrombosis with patent left innominate vein drainage, the venous return of the face, neck was impaired only on the right side giving rise to unilateral right sided symptoms. Given the similarity to SVC syndrome but with unilateral clinical findings, though a misnomer, unilateral SVC syndrome, this name appropriately represents the clinical scenario seen in these patients. The left innominate vein obstruction is expected more commonly due to its longer course.
What are the various causes of SVC syndrome and unilateral SVC syndrome?
Though the classical symptomatology and clinical signs described remain the same, there is a paradigm shift in the etiologies of SVC syndrome over the decades with malignancies now being the commonest as compared to infections previously. [Table 1] describes the various causes and correlating pathogenic mechanisms of SVC syndrome. 
Causes of unilateral SVC syndrome described are primary axillary thrombosis (Paget-Schroetter syndrome), aortic aneurysm, thrombosis, malignant thymomas and bronchogenic carcinoma.  Though these overlap with causes of SVC syndrome, however benign conditions like Paget-Schroetter syndrome should be kept in mind.
What are the venous collateral pathways that relieve venous congestion in SVC syndrome?
An obstructed SVC initiates collateral venous return to the heart from the upper half of the body through four principal pathways. The first and most important pathway is the azygous venous system, which includes the azygous vein, the hemiazygous vein, and the connecting intercostal veins. The second pathway is the internal mammary venous system plus tributaries and secondary communications to the superior and inferior epigastric veins. The long thoracic venous system, with its connections to the femoral veins and vertebral veins, provides the third and fourth collateral routes, respectively. [Figure 5] represents the major veins of thorax with the azygous venous collaterals and the various sites of SVC obstruction. 
Enumerate the various therapeutic options available for SVC syndrome?
The goals of SVC syndrome management are to relieve symptoms and to attempt cure of the underlying disease. Only a small percentage of patients with a rapid-onset SVC obstruction are at risk for life-threatening complications. Radiotherapy (RT) is a standard therapy for SVC syndrome due to malignancy (Hodgkin's lymphomas and lung carcinomas). ,, It is used as the initial treatment if a histological diagnosis cannot be established and the clinical status of the patient is deteriorating. Radiotherapy is often supported with adjuvant steroid therapy to prevent RT associated complications. The factors predicting response to radiotherapy include type and extent of malignancy, tumor restricted to single radiation portal, radiosensitivity of the tumor, absence of associated SVC thrombosis. ,, Chemotherapy may be preferable to radiation for patients with chemosensitive tumors (i.e., non-Hodgkin's lymphoma).  Intravascular device-associated SVC syndrome is treated with anticoagulation. Vascular bypass may be useful in benign diseases. , SVC stenting has been gaining importance as a treatment modality awaiting diagnosis in malignancies when radiotherapy and chemotherapy fail to provide benefit. [Table 2] enumerates the various therapeutic options. ,
Unilateral SVC syndrome, though extremely unusual and rare, is a clinical diagnosis. It should warrant a thorough clinical evaluation as it can be a presenting feature of a spectrum of diseases ranging from benign to malignant etiologies.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]