Massive benign pericardial cyst presenting with simultaneous superior vena cava and middle lobe syndromes
Journal of Cardiothoracic Surgery
Massive benign pericardial cyst presenting with simultaneous superior vena cava and middle lobe syndromes
Pankaj Kaul 0
Kalyana Javangula 0
Shahme A Farook 0
0 Address: Yorkshire Heart Centre, Leeds General Infirmary , Great George Street, Leeds, LS1 3EX , UK
A 66 year old woman presented in extremis with symptoms and clinical and radiological signs of simultaneous obstruction of superior vena cava and middle lobe of right lung secondary to compression by a massive benign anterior mediastinal cyst. Excision of the cyst at median sternotomy resulted in complete resolution of all symptoms. This report is unusual on account of a) the concomitant presence of superior vena cava and middle lobe syndromes caused by a benign cyst because of its sheer size producing obstruction of these structures and b) the complete resolution of all symptoms and signs after removal of the cyst. Benign anterior mediastinal cysts are unknown to cause either of the two syndromes. To our knowledge, it is the first report of a benign anterior mediastinal cyst causing either superior vena cava syndrome or middle lobe syndrome or both simultaneously. Etiologies of both superior vena cava and middle lobe syndromes are discussed in detail.
A 66 year old hypertensive and asthmatic chronic smoker
presented with 8 month history of progressively
increasing shortness of breath. Examination revealed an anxious,
tachycardic woman, breathless at rest with engorged neck
veins, purple discolouration of face, swelling of face and
neck and wheeze over whole of right chest. A
posteroanterior chest X ray showed a large mediastinal mass
occupying right middle and lower zones of chest with an
atelectatic middle lobe (fig 1). Lateral chest x ray
confirmed the anterior location of the mediastinal mass (fig
2). Spirometry demonstrated FEV1 0.84 L (47%
predicted), FVC 2 L (92% predicted), VC 2 L (92% predicted),
FEV1/FVC 42%, PEF120 L/min. Flexible bronchoscopy
showed normal appearances of the tracheobronchial tree.
CT Thorax showed a smooth ovoid mass in the right
anterior lower chest abutting the chest wall, diaphragm and
the right pericardium, and which showed a thin slightly
higher density wall and low density contents with average
CT number of 10, consistent with fluid (fig 3). There was
no mediastinal lymphadenopathy. An MR scan showed a
large cystic mass 11 × 11 × 8 cm in the right anterior
hemithorax, having the signal characteristics of neither a
vascular lesion nor a lipoma, in direct contact with
pericardium and, therefore, quite likely to be a pericardial
cyst, and causing external compression of right hilum,
right atrium and SVC (figs 4 and 5). Blood examination
revealed normal FBC, U&E, LFTs, calcium and glucose and
a slightly increased ESR at 25 mm/hr. Echocardiography
revealed an extracardiac mass abutting the right atrium
and ventricle and TOE, on operation table, confirmed the
presence of a huge anterior mediastinal mass (Fig 6).
Chest X ray (PA) view showing a large mediastinal mass
occupying middle and lower zones of right chest and causing
compressive atelectasis of middle lobe.
CT scan of chest showing a smooth ovoid low density mass
abutting the right anterior chest wall, diaphragm and the right
atrium and ventricle.
At median sternotomy, there was a 15 × 10 × 8 cm cyst,
adherent to the pericardium loosely, overlying SVC, right
atrium, right pulmonary hilum, the middle lobe and the
anterior basal segment of the lower lobe of lung and
compressing all the above structures (Fig 7). The large cyst was
dissected off intact from the above structures without
opening the pericardium while preserving the right
tFCioihgneusortfeXt2hreaym(erdigiahsttilnatael rmalavsisew) confirms the anterior
locaChest X ray (right lateral view) confirms the anterior
location of the mediastinal mass.
hFMeiRgmusitrcheaon4rdaxemonstrating a large cystic mass in right anterior
MR scan demonstrating a large cystic mass in right anterior
aFMniRgdusrrcigeahnt5svheonwtriincgleexternal compression of SVC, right atrium
MR scan showing external compression of SVC, right atrium
and right ventricle.
phrenic nerve (Fig 8). The middle lobe and the anterior
basal segment of lower lobe expanded completely. The
cyst was opened on table (Fig 9). It had a thin 2 mm wall,
was filled with 600 mls of haemorrhagic fluid with strands
of fibrin and the inner wall did not have any suspicious
masses although there were a few small clots attached to
TFmriegadunisaresestio6npahlaflgueidalfeillcehdomcaarsdsiogram shows a huge anterior
Transesophageal echocardiogram shows a huge anterior
mediastinal fluid filled mass.
Intraoperative photograph shows the cyst filling up almost
the entire anterior mediastinum, overlying SVC, right atrium,
right pulmonary hilum, the middle lobe and the medial basal
segment of the lower lobe.
it (Fig 10). Histopathology revealed a fibrous-walled cyst
with no lining epithelium. Within the fibrous wall,
chronic inflammatory cells and haemosiderin pigment
were noted. No malignancy was noted (fig 11). Patient
made uncomplicated recovery. Her facial swelling,
rubescent discolouration and venous distension resolved,
tachycardia disappeared and shortness of breath improved
dramatically. Postoperative chest X ray showed near
complete expansion of right lung (fig 12) and she was
discharged home 7 days after her operation. At follow up, 6
weeks later, she was completely asymptomatic.
Primary mediastinal cysts constitute approximately one
fifth of all mediastinal masses. The cysts may originate
from pleura or pericardium, tracheobronchial tree,
gastrointestinal tract, neurogenic tissue, thymus gland or
IFnitgruaorepe8rative photograph of the intact smooth walled cyst
Intraoperative photograph of the intact smooth walled cyst.
lymphoid tissue. Benign teratomas may present as
epidermoid cysts, dermoid cysts or cystic teratomas .
Mediastinal cystic masses may also result from specific or
nonspecific infections or parasitic infestations like
Anterior mediastinal cysts most commonly are
pleuropericardial, thymic, teratomatous or cystic hygromas.
Pleuropericardial cysts are benign mesothelial cysts that
arise as a result of persistence of one of the mesenchymal
lacunae that normally fuse to form the pericardial sac ,
or, as suggested by Lillie , due to the failure of an
embryological ventral diverticulum to fuse. Alternatively,
they may be believed to arise from the infolding of the
advancing edge of the pleura during its embryological
development. These cysts are unilocular, contain clear
watery fluid, present typically in anterior cardiophrenic
angle, more often on right side than left. Microscopically,
the wall has a single layer of mesothelial cells resting on a
loose stroma of connective tissue.
True thymic cysts are thin walled, unilocular and contain
normal thymic tissue within their walls and arise from
IFwniitgtrhuaorhepae9rmaotirvrehpahgioctfolugirdaph showing the thin walled cyst filled
Intraoperative photograph showing the thin walled cyst filled
with haemorrhagic fluid.
IsFnuitgsrpuaiocriepoeu1rs0atmivaesspehsotograph showing only a few clots and no
Intraoperative photograph showing only a few clots and no
eFHpiigsittuhorepelaiut1mh1owloigtyh schhorownsica ifnibflraomumsawtaolrleydcecyllstawn dithhenmoolisnidinegrin.
Histopathology shows a fibrous walled cyst with no lining
epithelium with chronic inflammatory cells and hemosiderin.
third branchial pouch. Microscopically, the wall is lined
by low cuboidal epithelium. However, malignant
degeneration within a thymoma may result in a cystic
thyePFxoigpsutaonrpseieo1rna2toivfemcihdedslet Xlobreay. (PA view) showing complete
Postoperative chest X ray (PA view) showing complete
expansion of middle lobe.
moma, with a residual mass projecting into the cavity of
the cyst from the wall.
Typically, lymphangiomas arise from neck and extend
into mediastinum. They contain chyle and are classified
according to the size of the spaces into cystic hygromas or
cavernous lymphangiomas. Cystic hygromas are
multiloculated, and a mediastinal hygroma is almost always an
extension of a cervical hygroma. However, rarely, a
uniloculated primary anterior mediastinal lymphogenous
cyst containing yellow or brown fluid may be found .
Teratodermoids are classified generically as benign germ
cell tumours. They are further divided into three
categories: epidermoid cysts which are lined by simple
squamous cell epithelium, dermoid cysts which have
squamous epithelial lining containing elements of skin
appendages like hair and sebaceous glands and teratomas
which may be solid or cystic and contain identifiable
cellular elements of two or three germinal layers .
Our patient had a massive fibrous but thin walled cyst
filled with brownish fluid. There was no lining epithelium
but there was chronic inflammatory cell infiltration with
lymphocytes, plasma cells, histiocytes, giant cells
containing pigment and lymphoid aggregates seen with no
evidence of malignancy. Considering the location of the cyst
in the anterior mediastinum and right hemithorax, it is
likely that this was originally a pleuropericardial or
thymic cyst whose epithelial lining was destroyed by
Benign anterior mediastinal cysts of pleuropericardial or
thymic origin in adult are mostly asymptomatic unless
they get secondarily infected which is unusual.
Bronchogenic cysts, which almost always arise in the visceral
compartment, in close relation to the trachea or bronchi, get
infected more frequently, particularly when there is a
persistent communication with the tracheobronchial tree. It
is extremely unusual for benign anterior mediastinal cysts
to cause compressive mediastinal symptoms, because
most normal, mobile mediastinal structures can conform
to pressure. Besides, anterior mediastinal cysts enlarge
anteriorly and inferiorly, in the path of least resistance.
Extrinsic or intrinsic compression of superior vena cava
(SVC) from a variety of benign and malignant processes
results in congestion of venous outflow from head, neck
and upper extremity. Important factors that determine the
nature of presentation include the rate and completeness
of obstruction, the etiology of obstruction and its site
relative to the drainage of azygous vein. Although syphilitic
aneurysms were responsible for nearly half of all reported
cases in the first half of the twentieth century , the most
common cause, in the current era, is malignancy, with
lung cancer being the most frequent cancer, the small cell
lung cancer being the most frequent cell type  and
lymphoma being the second most frequent tumor. Less than
5% of superior vena cava obstruction is caused by benign
disease, although the exponential increase in the number
of cardiac catheterizations, indwelling central venous
catheters, whether for prolonged monitoring by
pulmonary artery Swan-Ganz catheters or for long term
antibiotic or cancer chemotherapy with Hickman lines, as well
as transvenous pacemaker leads shall surely lead to a
revision of this conservative estimate. The other benign causes
of superior vena cava obstruction include substernal
goitre, Riedel's thyroiditis, fibrosing mediastinitis, and
aneurysms of brachiocephalic vessels. Postoperatively, SVC
obstruction can follow cardiac transplantation, Mustard
operation for transposition of great vessels, and, rarely,
rechannelling of partial anomalous pulmonary venous
An atelectatic middle lobe caused by extrinsic bronchial
compression of the long, slender and vulnerable middle
lobe bronchus, by malignant or inflammatory lymph
nodes, whether demonstrated or not, has long been called
middle lobe syndrome. Admittedly, the middle lobe has a
poorer drainage than the other lobes, is comprehensively
surrounded by lymph nodes and has very little collateral
ventilation. However, middle lobe syndrome can be
caused by entities as diverse as carcinoma of middle lobe
bronchus, mucosa associated lymphoid tissue (MALT)
lymphomas  or sclerosing Hodgkin's disease, primary
benign endobronchial diseases like tuberculosis  and
sarcoidosis, strictures of unknown etiology, foreign
bodies, fibrosing or resolving pneumonitis, sclerosing
mediastinitis, histoplasmosis, aspergillus  or
blastomyces  infections, obliterative bronchitis ,
bronchiectasis, bronchial hyper-responsiveness (BHR) and
asthma  and, rarely, bronchogenic or esophageal
Our patient presented with simultaneous superior vena
cava and middle lobe syndromes as well as compressive
atelectasis of medial basal segment of the lower lobe of
the right lung. Even though benign anterior mediastinal
cysts are not known to cause either of the two syndromes,
it was the sheer size and the weight of the cyst that was
responsible for causing such significant obstruction of
both of these vital anatomic structures. Removal of the
cyst resulted in instantaneous relief of both obstruction of
superior venecava and the compressive atelectasis of
middle lobe and medial basal segments of the right lower
The authors declare that they have no competing interests.
PK conceived, designed and drafted the manuscript, KJ
participated in the design of the study and helped in the
collection of figures, SAF carried out the preliminary
studies. All authors read and approved the manuscript
We would like to acknowledge the help of the following
at Leeds General Infirmary: Dr Ramnath, Consultant
Pathologist with the histopathology slides, Mr Stuart
Powell, Medical Illustration Unit and Dr S. Balaji, Consultant
Anaesthetist, with echocardiographic images.
Written informed consent was obtained from the patient
for publication of this case report and accompanying
images. A copy of the written consent is available for
review by Editor-in-Chief of this journal.
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