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Unusual presentation of massive intrathoracic schwannoma with concomittant pleural tuberculosis – case presentation and review of literature

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Razafimanjato Narindra Njarasoa Mihaja, Ravoatrarilandy M, Hunald FA, Rajaonera TA, Rakotovao HJL

Abstract: 

Schwannomas are the most common neurogenic tumors of the thorax, and may involve any thoracic nerve(1). We report the case of a 49-year-old male patient with a massive intrathoracic schwannoma. A thoracotomy resection of the tumor was performed. The presence of adhesions of the tumor to the chest wall pleura raised the suspicion of a malignancy. This article’s aim is to draw the attention to this infrequent pathology with concomitant tuberculosis, and to discuss different aspects regarding diagnosis and treatment of pleura schwannome.

Keywords: 
neurogenic tumor, pleural schwannoma, intrathoracic tumor

Case Presentation

pneA 49-year-old male with no significant clinical history presented to the emergency department with a one-month history of productive cough with white sputum, haemop-tysis and unexplained weight loss, associated with progres-sive shortness of breath on exertion, which had persisted despite courses of co-amoxiclav. On examination, his vital parameters (temperature, oxygen saturation, blood pres-sure, respiratory rate, pulse rate) were all within the nor-mal range for a man of his age. Physical examination revealed dull percussion note on right mid chest wall with diminished breath sound and occasional expiratory wheez-ing at the auscultation of the chest, and syndrome (facial swelling, neck distension). Lymph nodes examination is unremarkable and the rest of the examination was unre-vealing. Standard chest X-ray showed a large, well-defined mass in the the right hemithorax, around 18 cm in diam-eter, associated with displacement of the trachea to the opposite side (Figure 1). Initially, this was thought to be a bronchogenic cyst or a lymphoma process. Computed tomography (CT) scan of the thorax demonstrated a large (20x15x13 cm) well-circumscribed, heterogeneously enhancing rounded mass in the right hemithorax whose density was mostly similar to fluid, associated with a solid component in the uppermost part. The mediastinal struc-tures, particularly the trachea and right bronchus, were noticed to be compressed and displaced to the left side by this lesion (Figure 2). Examination of the sputum smear samples to identify AFB was positive. Fine needle aspiration was performed, but the specimen was insufficient for diagnosis. The results from percutanous biopsy confirmed a pleural schwannoma and eliminated a lymphoma process. Surgery was planned after ruling out an intraspinal com-ponent of tumor. Complete excision of the well-encapsu-lated mass was achieved through the right posterolateral thoracotomy (Figure 3A).

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A 20-cm tumor was found in the right chest cavity, adhering closely to the parietal pleura and superior vena cava, which was severely dilated. The mass was found to be benign schwannoma without malignant compo-nents and the anatomopathological examination of pari-etal pleura retained it to be tubercular (Figure 3B). The postoperative course of the patient was uneventful. The respiratory and vascular symptoms and the facial edema resolved immediately after the surgery. The patient returned to his normal life and recovered gradually through regular chest physiotherapy. He has been fol-lowed-up for one year, with no evidence of recurrence.

Antitubercular treatment according to the National Tuberculosis Control Program (NTP) standards in our country was started and he performed well, being declared cured and in our regular follow-up.

Discussion

The primary pleural schwannomas are usually benign(2), yet malignancy has been reported in some cases(3). They account for 1-2% of all thoracic tumors(3).

Pleural schwannomas can occur at all ages, though they are uncommon in children. Both genders are equal-ly affected, predominantly in the third or fourth decades of life(4,5).

Shin-ichi Takeda et al. analyzed the records of 146 patients with intrathoracic neurogenic tumors who were treated over the past 50 years. 20.5% of the neoplasms were malignant, occurring predominantly in the first 5 years of life. This study concluded that the age of patient seemed to be the most important clinical parameter for distinguishing between histological type and rate of malignancy for neurogenic tumors(6).

Intrathoracic neurogenic tumors occurs predomi-nantly (90%) in the mediastinum and about 10% origi-nate in the peripheral nerve fibers from the intercostal nerves or pleural nerves(7,8). Schwannomas (also known as neurilemmomas or neurinomas) are highly vascular nerve sheath benign tumors that arise from the neural crest-derived Schwann cells(9).

The risk of malignancy in a nerve sheath tumor is very small (2-5%), frequently associated with von Recklinghausen syndrome (4% of cases), other neurofi-bromatoses or radiation exposure, when the risk increas-es to 10-20%(7,10,11).

The association of schwannoma with concomitant tuberculosis is a very rare entity. A literature review was performed via PubMed, using the MeSH terms ‘benign schwannoma’ and ‘tuberculosis’ and identified two similar case reports of intrathoracic schwannoma associated with tuberculosis(7,12). However, we found only one case of similar size to our observation, reported by David D. Odell et al(10).

Up to 80% of cases are asymptomatic, and diagnosis in young and middle-aged adults is generally fortuitous, fre-quently appearing as incidental radiological findings(9,12,13). In our case, the presentation with superior vena cava syn-drome is rare, making our patient atypical, reflecting clini-cal mutility and insidious evolution which can spread over several years, and explains the occurrence of the giant forms of this type of tumor. These symptoms are due to compression of neighboring structures(14).

A variety of diagnostic imaging modalities can be utilized to delineate pleural schwannomas. Generally, chest wall neurilemmomas are evaluated by radiologic examination for planning the surgical approach, includ-ing CT and magnetic resonance imaging (MRI).

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CT scan remains the diagnostic imaging modality of choice for these neoplasms. CT scan can outline the size, number, and exact location of the lesions. CT scan can also demonstrate cystic and/or solid components of the tumor. Unenhanced CT demonstrates well-marginated soft-tissue mass with possible surrounding fat attenu-ation (“split fat” sign), may contain areas of low attenu-ation corresponding to fat or cystic degeneration, and calcifiation may be seen in 10% of tumors. Contrast-enhanced computed tomography (CECT) shows an homogeneous enhancement in small tumors and hetero-geneous enhancement in larger tumors(15).

Malignant pleural schwannomas have similar fea-tures on CT scan; however, they are usually associated with the presence of pleural nodules, pleural effusions, and metastatic pulmonary nodules(15).

In the case of our patient, the presence of dense adhesions and increased vascularity were in favor of malignant tumor component. This could have been sec-ondary to the extension of inflammation reponse and fibrous reaction from the pleura tuberculous on to the capsule of the tumor and mimicked the features of malignancy.

MRI is the preferred method for the assessment of peripheral nerve sheath tumors(5). Vessels in neurinomas are usually prominent and their rich vascular supply is reflected in the often intense enhancement of these tumors on imaging studies(5). Pleural schwannomas are typically hyper-/isointense on T1-attenuated images and heterogeneously hyperintense on T2-attenuated images(3,15). Particularly, MRI should be performed in patients with suspected posterior mediastinal neuro-genic tumors to exclude intra-spinal tumor extension(16). Thus, preoperative radiologic evaluation alone is enough without needle aspiration biopsy(16).

For giant shapes like our case, intra-thoracic schwan-nomas should be included in the differential diagnosis of posterior mediastinal masses. They include sympa-thetic ganglion tumours (neuroblastomas, ganglioneu-roblastomas, ganglioneuromas) and paragangliomas (chemodectomas and pheochromocytomas), lymphad-enopathy, enteric cysts, bronchogenic cysts, oesophageal tumours, aneurysms and paraspinous abscess(12).

In the absence of MRI, as in our observation, a pre-operative percutanous biopsy of the tumor, when feasi-ble, is necessary in order to lead to the definitive d iag nosis of benig n tumor and to avoid overtreatment(5).

Microscopically, Antoni A and Antoni B areas are revealed in the majority of pleural schwannoma cases. Antoni A represents areas of hypercellularity with verocay bodies. Antoni B areas of myxoidhypocellularity exhibit degenerating changes (i.e., cyst formation, haemorrhage, calcification, xanthomatous infliltration and hyalinisa-tion)‌(3). Immunohistochemically, pleural schwannomas typically stain diffusely and strongly positive for S100 protein. On the other hand, they stain negatively for CD-15, CD-30, CD-34, and pan-cytokeratin(3,15).

The standard care of management of pleural schwan-nomas is primarily surgical resection(14,17).

In literature, the authors are unanimous that, com-pared to thoracotomy, VATS has better outcomes in terms of duration of surgical procedure, the amount of blood loss and length of drainage time. Complete resec-tion can be achieved with low morbidity (smaller inci-sions, thereby resulting in less pain, fewer lung complications, shorter hospital stays, more rapid recov-ery, with return to normal activities) and less aesthetic damage(5,10,18,19).

A case series of 60 consecutive patients with a neu-rogenic tumor of the chest during 30-year experience concluded that VATS seems feasible as the approach for the thoracic neurogenic tumor since it is less invasive and provides an appropriate view for the operation(20).

A combined Chinese experience reports a thoraco-scopic removal successfully of intrathoracic neurogenic tumors on average 3.5 cm in greatest diameter(21). However, the video-assisted thoracoscopy may be con-traindicated in tumors larger than 6 cm(14,22).

David D. Odell et al. report a case of intrathoracic schwannoma measuring 27 cm in diameter and conclude that the clamshell incision, compared with the median sternotomy, offers excellent exposure of the pulmonary hilum, which is especially helpful in the setting of cen-trally located tumors(10).

In our case, we decided to perform an approach through a right posterior thoracotomy in the 6th inter-costal space due to the size of the lesion and the possibility of an intraspinal component of the tumor, which necessitate a combined or staged approach, involving both neurosurgical and thoracic procedures.

Conclusion

This case report highlights the need to be aware of the potential coexistence of tuberculosis and intra-tho-racic schwannoma, hence the necessity of a systematic identification of an AFB on a sputum smear samples before any thoracic surgery in our country. Conversely, any positivity of the AFB test should not conclude for any intrathoracic mass to be a tuberculoma, without the confirmation by the examination of the tissue through a biopsy or surgical excision.

Acknowledgements

The authors are very grateful to Razafimanjato A. Esteban for his assistance to accomplish this work.

AUTHORS AFFLILIATION:

  1. Teaching Hospital of Joseph Ravoahangy Andrianavalona Ampefiloha, Department of Surgery & Division of Thoracic Surgery, BP: 4150, Faculty of medecine of Tananarive CP : 101

  1. Teaching Hospital of Joseph Ravoahangy Andrianavalona Ampefiloha, Anaesthesia reanimation units, BP: 4150, Faculty of medecine of Tananarive CP : 101

  1. Teaching Hospital of Joseph Ravoahangy Andrianavalona Ampefiloha, Department of Surgery & Division of Pediatric Surgery, BP: 4150, Faculty of medecine of Tananarive CP : 101

 

 

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