Superior vena cava syndrome due to mediastinal Gardner fibroma presenting as syncope

Abstract

Superior vena cava (SVC) syndrome refers to the clinical manifestation due to an obstruction in the SVC; resulting in decreased venous return from the head, neck and upper extremities. The obstruction can occur either due to tumour invasion of the vessel wall with associated thrombus or due to vessel wall compression by the tumour mass. The patient being reported is a young male who presented with recurrent episodes of syncope and was found to have mediastinal Gardner fibroma causing SVC syndrome. Gardner fibroma is a benign soft tissue lesion; and its occurrence in the mediastinum resulting in SVC syndrome has not been reported yet.

Background

Superior vena cava (SVC) syndrome is a set of clinical manifestations caused either by an SVC thrombosis associated with neoplastic invasion of the venous wall or an external compression by a tumour mass against the vessel wall; resulting in severe reduction in venous return from the head, neck and upper extremities. Gardner fibroma is a benign soft tissue lesion that can occur in the paraspinal region, chest wall, back, abdomen and head/ neck. Mediastinal Gardner fibroma resulting in SVC syndrome is an unreported scenario.

Case presentation

A 37-year-old man, painter by occupation, presented to the medicine department with syncopal attacks (3–4 episodes) lasting less than a minute over the last 2 months. He had also noticed swelling of his face and neck prior to these episodes. He did not have any comorbid condition and was not on any regular medications.

On presentation, his vitals and systemic examinations were normal. He did not have any facial puffiness, neck swelling or engorged veins.

Investigations

His blood investigations like complete blood count, renal and liver functions, electrolytes, calcium, thyroid stimulating hormone (TSH) and HbA1c were normal. MRI brain and Holter monitoring were also normal. His chest X-ray had mild widening of right paratracheal strip (figure 1). Mantoux test was negative. Echocardiography showed mildly dilated right atrium (RA) with mild tricuspid regurgitation and moderate pulmonary artery hypertension (PAH). There was a mean gradient of 12 mm Hg across SVC-RA junction. Contrast enhanced CT thorax revealed a homogenous soft tissue mass encasing and severely narrowing the right main pulmonary artery (figure 2). The lesion was insulating between the ascending aorta anteriorly and left atrium posteriorly, extending caudally into the atrio-ventricular groove. The SVC was narrowed at its junction with the RA (figure 3). The lesion had contact with the anterior wall of right bronchus, without causing any luminal compromise. Doppler study of carotid arteries was normal.

Figure 1.

Chest X-ray showing mild widening of right paratracheal stripe.

Figure 2.

CT thorax showing mediastinal mass encasing and compressing right pulmonary artery (red arrow).

Figure 3.

CT thorax showing mediasitnal mass compressing right atrium at superior vena cava drainage site (blue arrow).

Treatment, outcome and follow-up

Surgical procedure: A hard mass was seen engulfing the right pulmonary artery, posterior to the ascending aorta and SVC. There was absolutely no plane of dissection between the aorta and pulmonary artery, and hardly any lumen at the junction of SVC and RA. Hence, it was decided to cannulate the aorta innominate vein and inferior vena cava. The SVC-RA junction was augmented with autologous pericardial patch (figure 4).

Figure 4.

Autologous pericardial patch augmentation of superior vena cava-right atrium junction.

Histopathological examination of the mediastinal biopsy tissue showed dense hypocellular hyalinised fibrous tissue with intervening cracks. The spindle cells also showed small uniform nuclei. The periphery had fat with moderate perivascular lymphoplasmocytic infiltration. The cells were positive for CD34 and ß-catenin, and non-reactive for smooth muscle actin (SMA). The findings were consistent with Gardner fibroma (figure 5). He was discharged on oral sildenafil (20 mg three times per day) and reviewed every month, and was asymptomatic. His repeat echocardiography after 2 months showed a mildly dilated RA with mid tricuspid regurgitation and mild PAH. There was no gradient across SVC-RA junction. Upper and lower gastrointestinal endoscopic evaluations (to rule out familial adenomatous polyposis) were normal. Contrast enhanced CT thorax (CECT) thorax, after 8 months, did not show any increase in size or extend of the lesion, with significant increase in the calibre of terminal SVC (figure 6).

Figure 5.

Histopathology suggestive of Gardner fibroma (H&E stain ×40 HPF). HFP; High power field.

Figure 6.

Postoperative CT thorax showing increase in the calibre of terminal superior vena cava (red arrow).

Discussion

SVC syndrome refers to clinical manifestations due to SVC obstruction, resulting in decreased venous return from the head, neck and upper extremities. It was first described by William Hunter in the year 1757 in a patient with syphilitic aortic aneurysm.¹ The obstruction may be due to a neoplastic invasion of the venous wall with associated intravascular thrombosis or by external pressure exerted by a tumour mass against the wall of SVC. Majority of the cases are caused by malignant mediastinal tumours²; of which 85% are due to lung cancers, particularly small cell and squamous cell carcinomas. Other uncommon malignant causes include Hodgkin’s lymphoma, primary mediastinal germ cell tumours, and metastatic cancers from testis and breast.^{3 4} The non-malignant aetiologies include aortic aneurysm, mediastinal fibrosis, thyromegaly, thymoma, Behcet’s syndrome and infections like tuberculosis, histoplasmosis, syphilis and actinomycosis.^5–8 These patients present with swelling of the face, arms, neck, dyspnoea and cough, and dilated neck veins. Other less common symptoms include headache, syncope, nasal congestion, lingual swelling, hoarseness of voice, dysphagia, epistaxis and haemoptysis.³ Syncope is an unusual presentation.⁹

Gardner fibroma is a benign proliferation of thick, irregularly arranged collagen bundles with interspersed fibroblasts. More than 80% of the cases are found in association with Gardner-type familial adenomatous polyposis. The condition is mainly seen in children during the first decade of life, but can extend to the fourth decade. Both sexes are equally affected. The commonly involved sites are chest wall, back, abdomen, head/ neck, extremities and superficial and deep soft tissues of paraspinal region. Macroscopically, the size ranges from 1 to 10 cm. The lesion is firm and rubbery, with tan surface and scattered yellow areas. Microscopically, there is uniform hypocellular proliferation with irregularly arranged collagen fibres with cracks, bland spindle cells and sparse mast cells. On immunophenotype, it is reactive for CD34 and non-reactive for MSA, SMA and desmin. Focal nuclear reactivity is common with β-catenin.¹⁰

As mentioned earlier, non-malignant aetiologies for SVC syndrome are uncommon. Gardner fibroma is a benign soft tissue tumour that can occur in the chest. Mediastinal Gardner fibroma causing SVC syndrome due to vessel wall compression, to the best of our knowledge, has not been reported yet. Moreover, our patient presented with syncope, which is a rare scenario.

Learning points.

• Gardner fibroma is a benign soft tissue tumour that is commonly seen in association with familial adenomatous polyposis.

• Mediastinal Gardner fibroma causing superior vena cava (SVC) syndrome is an unreported scenario.

• Syncope is an uncommon presentation of SVC syndrome.