Huge mediastinal cystic lesion: a case report

Amita Yadav, Rajendra Mathur, Sanjeev Devgarha, Viju Abraham, Anula Sisodia

Department of Cardiothoracic and Vascular Surgery, Sawai Man Singh Medical College and Hospital, Jaipur, India

DOI : 10.5606/tgkdc.dergisi.2015.9688

Abstract

Thymic cysts are rare, and because most are asymptomatic when small in size, they are usually detected incidentally as unsuspected masses on chest radiographs. In this article, we report a rare case of a huge thymic cystic lesion abutting the major vessels of the mediastinum. Chronic respiratory and cardiac symptoms developed in a patient who presented with a mediastinal cystic mass after which widening of the mediastinal shadow was confirmed on chest radiographs. Thymic cysts should be added to the list of thymic abnormalities that may occur in patients with compressive mediastinal masses, which may be life threatening.

Abstract

Among the mediastinal cysts, those that are thymic make up between 3 and 28.6% of all reported cases.[1-3] These tumors are generally asymptomatic and are usually diagnosed accidentally during a radiological evaluation of the chest for unrelated conditions. In addition, symptoms appear later when the mass exhibits compressive features. In addition, one rare case of a medistinal thymic cyst mimicking a pericardial cyst has been reported.[1] Herein, we present the case of a patient with a large thymic cyst abutting the major vessels of the mediastinum.

Case Presentation

A 40-year-old female patient was admitted to our facility with a cough, palpitations, and dyspnea on exertion that had persisted for two months. She had no history of pneumonia or pleural effusion. A preoperative chest radiograph showed a large left anterosuperior mediastinal mass that had been previously described as an asymptomatic pericardial cyst on a previous chest radiograph. Furthermore, the patients family history was non-contributory, and there was no past history of pneumonia and chest pain. Moreover, the patients hemodynamic parameters and laboratory data were also within normal limits.

A chest X-ray (Figure 1) showed a homogenous opacity in the anterosuperior mediastinum adjacent to the right heart contour, but the lung transparency and cardiac silhouette were normal. Echocardiography detected an ejection fraction (EF) of 55%, minimal pericardial effusion localized to the right side of heart, normal chamber dimensions, and no regional wall motion abnormalities.

Figure 1: A chest X-ray showed a homogenous opacity in the anterosuperior mediastinum.

The patient then underwent chest computed tomography (CT) which revealed a cystic lesion in the anterior mediastinum extending from the level of thoracic inlet to the T10 vertebra. The lesion was abutting the mediastinal vascular structures, anterolateral chest wall, and anterior pericardium via a fat plane, and tiny, discrete foci of fat densities were seen within the lesion. In addition, a curvilinear segment of collapse was visible adjacent to the lateral margin of lesion, but there was no evidence of any abnormal calcification (Figure 2).

Figure 2: Chest computed tomography which revealed a cystic lesion in the anterior mediastinum extending from the level of thoracic inlet to the T₁₀ vertebra. T.

A median sternotomy was then performed in order to excise the cyst, and this revealed a huge, elongated cyst with two non-communicating components originating from the thoracic inlet that were attached to the pericardial surface of the mediastinum by adhesions. Furthermore, it was abutting the superior vena cava (SVC) as well as the brachiocephalic, carotid, and subclavian arteries and was also occupying half of the right hemithorax laterally. The patient left the operating room in good condition, and her postoperative recovery was favorable.

On gross appearance (Figure 3), the external surface of the cyst was smooth. Moreover, it contained thin serohemorrhagic fluid and gross amorphous parietal material.

Figure 3: Gross appearance, the external surface of the cyst was smooth.

A microscopic examination of the cyst wall indicated that it was composed of a thick layer of hyalinized connective tissue with lymphoid foci and a central skeleton of Hassalls corpuscles and nodular aggregates of foamy cells. There was no epithelial lining focally, and pathological examination revealed two loculations in the resected specimen. A tissue diagnosis of the benign thymic cysts was made because the cyst wall contained thymic lymphoid tissue; however, there was no evidence of malignancy.

Case Presentation

Discussion

In the anterior mediastinum, tumors and cysts of a thymic origin, germ cell tumors, parathyroid adenoma, lymphoma, and intrathoracic goiters are prevalent.[1] The thymus develops from the third pharyngeal pouch together with the inferior parathyroid glands at the fifth week of gestation. The developing thymus maintains its close relationship with the parietal pericardium and descends with the pericardium between the 7^th and 8^th gestational weeks to assume its characteristic location in the superior anterior mediastinum anterior to the great vessels.[4]

Thymic cysts may be congenital or acquired. Congenital thymic cysts are remnants of the thyropharyngeal ducts and therefore can occur in the neck or mediastinum. These cysts are usually <6 cm in diameter. In addition, they can be uniloculated or multiloculated and have thin walls. However, acquired cysts are multiloculated with variable cyst wall thickness and range in size from 3 to 17 cm.

The common symptoms for thymic cysts are chest pain, dyspnea, and a cough, but hoarseness of voice[3] and respiratory distress have been reported in rare cases. In 1897, Loupaltl recorded the presence of the first congenital mediastinal thymic cyst during the necropsy of an 18-year-old woman, and the first incidence in the United States occurred in a report by Spees in 1938 when he discovered a thymic cyst in a 25-year old man during a necropsy.[7,8]

The prognosis for thymic cysts is excellent. Total surgical removal is recommended, and no local recurrence have ever been reported. There have also never been, to the best of our knowledge, any reports of malignant degeneration associated with congenital thymic cysts. Nevertheless, a preoperative diagnosis is almost never made. In fact, the actual diagnosis sometimes does not occur until after a pathological examination of the surgical specimen.

Discussion

Conclusion

Our case was unusual because of the huge size of the lesion abutting the major vessels of the mediastinum and also because it occupied half of the right hemithorax. In our patient, the radiological and operative findings were able to establish the nature of the mass to ensure optimal surgical treatment. Even though these cysts are rare, the possibility of their presence should be kept in mind when symptoms similar to our case are present.

Declaration of conflicting interests
The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Funding
The authors received no financial support for the research and/or authorship of this article.

Conclusion

References

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3) Takeda S, Miyoshi S, Minami M, Ohta M, Masaoka A, Matsuda H. Clinical spectrum of mediastinal cysts. Chest 2003;124:125-32.

4) Moore KL, Persaud TV. The pharyngeal apparatus. In: Moore KL, Persaud TVN, editors. The developing human: Clinically oriented embryology. 7th ed. Philadelphia: Saunders; 2003. p. 202-40.

5) Krongrad E, Gunnlaugsson GH, Feldt RH, McGoon DC. Mediastinal masses following corrective surgery for congenital heart disease. Mayo Clin Proc 1970;45:748-54.

6) Sltzer RA, Mills DS, Baddock SS, Felson B. Mediastinal thymic cyst. Dis Chest 1968;53:186-96.

7) Indeglia RA, Shea MA, Grage TB. Congenital cysts of the thymus gland. Arch Surg 1967;94:149-52.

8) Speer FD. Thymic cyst: Report of a thymus presenting cysts of three types. N Y Med Coll Flower Hosp Bull 1938;1:142-50.

References

Keywords : Anterior mediastinal mass; chest; thymic cyst

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