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| Journal of the New Zealand Medical Association,
16-February-2007, Vol 120 No 1249
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Multi modality treatment of an extensive pleural
thymoma
Elizabeth Clayton, Yasotha Kathiravel, Harsh Singh
A 47-year-old male presented with numbness of his tongue,
and altered taste sensation. He subsequently complained of malaise and
right-sided pleuritic chest pain, with an associated cough, slight mucoid
sputum, and fever. He was a lifelong non-smoker with no significant past medical
history. A provisional diagnosis of lower respiratory tract infection was made,
and he was initially managed with oral antibiotics. A chest radiograph
subsequently revealed pleurally based lesions.
After the patient developed further symptoms of weight loss,
anorexia, dysphonia, increasing fatigue, and nasal regurgitation of water, a
clinical diagnosis of myasthenia gravis (MG) was made.
An initial computed tomography (CT) scan of the thorax
showed extensive multifocal pleural thickening and nodularity of the right lung,
with involvement of the fissure and intra parenchymal pulmonary nodules were
noted. The right paratracheal and sub carinal lymph nodes were enlarged. The
core biopsy (under CT guidance) revealed features of a type B1
thymoma.1 Based on the Masaoka clinical staging
system2 this was considered as stage IVA
disease, defined as pleural or pericardial metastatic spread.
Figure 1. Inoperable extensive right pleural
thymoma
 However the initial size and extent of the tumour, made it
unsuitable for surgical resection (Figure 1). Following a multimodality
discussion, it was thought that surgical debulking, and possible complete
resection, could be considered, following review of response to neoadjuvant
chemotherapy. He underwent a chemotherapy regime of cisplatin, doxorubicin, and
cyclophosphamide for four cycles over an 8-week course.
Post chemotherapy CT demonstrated marked interval reduction
in the size of the mediastinal and right pleural disease (Figure 2). He
underwent an extended right pleuro pneumonectomy with excision of the diaphragm
and pericardium. The thymus gland and a large area of pericardium with tumour
involvement were excised. The pleural cavity showed no further evidence of
tumour seedlings.
Figure 2. Post chemotherapy marked interval
reduction of pleural thymoma
 Postoperatively he spent less than 24 hours in the intensive
care unit prior to transfer to the cardiothoracic ward. On the fifth
postoperative day he developed an episode of acute shortness of breath, and
tachycardia. He underwent a VQ scan, which showed no evidence of a pulmonary
embolus. He returned home 9 days postoperatively.
Histology revealed an extensive thymoma mixed type
B2/B31 with extensive focal capsular invasion
and tumour identified abutting lung parenchyma, involving pleura, and
pericardium, with no evidence of lymph node metastases.
Two months postoperatively the patient presented to clinic
with a week’s history of productive cough associated with pyrexia. Chest
radiography was unchanged from previous films. He was commenced on intravenous
antibiotics and admitted to hospital for observation. He was found unresponsive
the next morning.
Post mortem revealed that the cause of death was respiratory
failure in the context of acute bronchitis in his remaining left lung. It was
noted that his co-existing myasthenia gravis might have been the cause for his
respiratory depression. There was no evidence of tumour reoccurrence at post
mortem.
DiscussionThymomas are derived from epithelial cells of the thymus and
are the commonest anterior mediastinal neoplasm; in the adult population,
however, the overall incidence is rare.3 The
propensity of the tumour to be malignant is determined by the invasiveness of
the thymoma, locally, via pleural dissemination, or systemic
metastases.4
Peak incidence of onset is between 40 and 60 years of age,
with no sexual predilection.5 Presentation of
thymomas varies, from local symptomatic symptoms such as cough, to incidental
detection on chest radiographs, or from screening due to its associations with
autoimmune and immunodeficiency disorders.5,6
Up to 30 to 65% of patients with thymoma have been reported
to suffer from myasthenia gravis. Furthermore, 28% will present with other
immune disorders such as lupus erythematous, pure red cell aplasia, Cushing's
syndrome, and hypogammaglobulinaemia.6
Traditionally, thymomas are classified into three
histological types based on the predominant cell type of lymphatic, epithelial
and lymphoepithelial.4 Recently the World
Health Organization reached a histological classification based on both
morphology and lymphocyte to epithelial cell
ratio.1 In 1981, Masaoka developed an anatomic
classification based on the presence or absence of gross or microscopic invasion
of the capsule and the presence or absence of
metastases.7 This has since been upgrade in
1994 to the modified Masaoka staging system and is now the most widely accepted
staging system on which current management options are
based.2
We present a case of an extensive pleural malignant thymoma
(IVa) with myasthenia gravis. Management involved a multimodality team of
cardiothoracic surgeons, oncologists, radiologists, histopathologists, and
neurologists. The extensive tumour, thought to be initially unresectable, was
subsequently completely resected, following neoadjuvant chemotherapy. His death
was thought to be related to infection, possibly complicated by myasthenia
gravis.
Surgical intervention is the treatment of choice by wide
consensus, as complete resection remains an important factor in the survival of
patients with locally advanced malignant
thymoma.8.9 However, radical resection is not
always feasible for invasive and metastatic lesions (stages III and
IVa).2
Thymomas are seen to be both chemo- and radio-sensitive, and
recent reports using preoperative (neoadjuvant or induction) chemotherapy to
transform a patient with inoperable disease into a patient with operable disease
have shown good results.8,9
Venuta et al analysed multimodality treatment of thymomas
compared to historical controls (those who received surgery alone). They showed
that the complete resection rates were improved in the multi modality group
relative to the surgery alone group (77% vs 33.3% for stage IV
tumours).9
Shin et al have shown good response to neoadjuvant
chemotherapy of 92% in 12 patients (stage III and IVA), and subsequent complete
resection in 82%. Following adjuvant chemotherapy and radiotherapy they have
shown disease-free survival at 7 years to be
73%.8 Ongoing problems with research relate to
low incidence, and therefore small numbers of patients with thymoma to produce
randomised control trials.
This case demonstrates that thymomas are often associated
with paraneoplastic syndromes such as myasthenia gravis and therefore their
treatment may affect prognosis.10 Furthermore,
as this case highlights, multimodality treatment with neoadjuvant chemotherapy,
followed by radical surgical resection, is highly effective and may cure locally
advanced, unresectable thymomas.
Author information: Elizabeth S J Clayton;
Yasotha Kathiravel; Harsh P Singh; Department of Cardiothoracic Surgery,
Christchurch Hospital, Christchurch
Acknowledgement: We acknowledge the
assistance of Dr Sharyn MacDonald for radiographic images and
interpretation.
Correspondence: Harsh P Singh, Department
of Cardiothoracic Surgery, Christchurch Hospital, Private Bag 4710,
Christchurch. Fax: 03 364 1361; email: HarshS@cdhb.govt.nz
References
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