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January - March 2007: 
Volume 20, Issue 1

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ARCHIVE

A case of mucoepidermoid lung tumour; bronchoscopic findings of similar cases in Northern Greece during the last decade
Abstract
SUMMARY. Mucoedidermoid lung tumours represent a rare group of primary lung cancers. They are categorized as salivary gland tumours due to their discrete histologic characteristics. They are usually low grade tumours, located endobronchially, and distant metastasis are rare. The treatment of choice is surgical resection, followed in some instances by irradiation as adjuvant or palliative therapy. Completely resectable low grade tumours generally have an excellent prognosis. The case is presented of mucoedidermoid lung tumour in a young adult and a short review is made of similar cases diagnosed in Nothern Greece during the last decade. Pneumon 2007; 20(1):95-98.
Full text

Case report

 

This is a case of a 40 year-old male, who was referred from a district hospital for investigation of a round lesion located in the left main-stem bronchus.

 

The patient’s current disease had been detected approximately 5 months earlier, when he underwent chest computed tomography (CT) for investigation of an opacity in the left hilum, observed on chest X-ray for investigation of a contralateral left stridor. The patient himself complained of a wheeze located in the lateral lower left thoracic wall.

 

The patient’s history revealed initiation of the symptoms about three years previously. At first the symptoms receded with antibiotic treatment, but later they recurred. Inhaled bronchodilators did not improve the symptoms, so the patient was admitted for further investigation by imaging techniques.

 

Personal History

 

The man was a former smoker (22 pack/years) who stopped smoking 9 years earlier. Therewere no concomitant conditions, no prior use of medicine.

 

Clinical Findings

 

He was an able-bodied adult, with appearance and nutrition satisfactory. During chest auscultation an inspiratory and expiratory wheeze was detected in the posterior thoracic wall and specifically over the middle pulmonary lobe. No hepatosplenomegaly or enlarged cervical, supraclavicular or axillary lymph nodes were observed.

 

Laboratory findings

 

Haematological and biochemical tests were normal, with the exception of a slightly high ESR (40 mm during the first hour). Tumour markers were negative, and arterial blood gases were also normal. Spirometry results revealed a mild mixed disorder, mostly restrictive, and FVC was 4,10 L (69% predicted), FEV1/FVC 75% and FEF25-75 was 2,4 L (55% predicted).

 

Chest X-ray

 

Radiography revealed a rounded opacity with regular borders located under the left hilum (Figure 1).

 

Figure 1. Chest X-ray: A relatively well-defined opacity located posterior to the left pulmonary hilus.

Chest computed tomography

 

CT scan showed a round-shaped mass in the left hilum, obstructing the lower lobar bronchus with satisfactory lung radiolucency and absence of lack of enlarged mediastinal lymph nodes or pleural effusion (Figure 2). It is noted that similar findings were observed in a chest CT conducted 2 years earlier, but they were not evaluated at that time (Figure 3).

 

Figure 2. CT scan: A round-shaped formation obstructing the lower lobar bronchus.

 Based on the evidence presented above, the patient was subjected to fiberoptic bronchoscopy, which revealed: a polypoid whitish mass fully obstructing the left lower lobar bronchus. Several biopsy samples were obtained and a bleeding tendency was successfully managed with adrenaline saline infusion. The histological report revealed malignant tumour development on the respiratory mucosa with morphological findings in agreement with those observed in salivary gland type tumours and morphological findings more indicative of mucoepidermoid than of adenoid cystic carcinoma. Brain and upper-lower abdominal CT, and bone scintiscan, were subsequently conducted and were negative for secondary sites.

 

Figure 3. CT scan 3 years earlier: A round-shaped formation located in the lower lobar bronchus.

Based on the histological analysis and the negative staging, the patient was transferred to the Department of Thoracic Surgery, where he successfully underwent lower lobectomy. Three radiopaque clips were placed on the lung stump, in case of post-surgery radiation therapy. Histological analysis of the surgically removed tissue revealed: ‘‘Medium size squamous cells with eosinophilic cytoplasm, mucous-producing cells and intermediate type cells in clusters and often in tubular or cribriform formations.‘’, confirming the initial diagnosis.

 

Discussion

 

Primary mucoepidermoid tumours are a unique and rare type of tumours. Although their existence has been adequately documented in the international literature, this has mainly been through case reports. Recently, increasing experience has enabled physicians to define their prevalence, clinical expression, therapy and extent of histological findings.1,2 The rarity of these tumours is indicated by the fact that they represent only 0.1%-0.2% of all lung tumours and 1%-5% of bronchial adenomas.3,4

 

The WHO defines mucoepidermoid tumour as a tumour mass characterized by the presence of mixed mucoid-producing, squamous and intermediate cells.5 Their morphology is similar to that of salivary gland tumours, which are categorized in to two types, benign and malignant; mucoepidermoid tumours belong to the second category.6

 

The age of presentation is 4-78 years, but almost half of the patients are under 30 years.3,7 Clinical manifestations are commonly related to irritation or airway obstruction and include cough, wheezing, shortness of breath, haemoptysis and occasionally fever or weight loss. Up to 28% of the patients may be asymptomatic.8 Chest X-ray usually reveals nodular opacity, pulmonary infiltrations, post-obstructive pneumonia or atelectasis, but may also be normal.9 On chest CT, the tumour may present as rounded or lobular with a diameter ranging from 9 mm to 6 cm.3,7,9

 

Macroscopically, mucoepidermoid carcinomas are usually polypoid tumours of gray, light brown or pink colour and are located transbronchially. Their main characteristic is that they extend as far as the nearby bronchial divisions.9 They are usually located in the main stem or lobar bronchi, occasionally in segmental bronchi and rarely in bronchioles.10-13

 

During the last decade, according to archives from the Department of Bronchoscopy in the “Papanikolaou” General Hospital of Thessaloniki, only six similar cases have been documented in Northern Greece. Of these, four were reported in males and the rest in females, aged 57-76 years. The most frequent location was the lower lobar bronchi, whereas in two cases the tumour was located in the upper right lobar and in only one in the middle lobar bronchus.

 

Low malignancy tumours are almost always located in the bronchial tree, while high malignancy tumours often extend in to nearby tissues. Moreover, low malignancy tumours usually appear as polypoid masses and have low mitotic activity, nuclear polymorphisms or cell necrosis and 75-80% of all mucoepidermoid tumours are histologically characterized as low malignancy.3,7

 

This patient was 40 years-old, a former smoker with no specific symptoms. The only pathological evidence was contralateral auscultation findings and subsequently a nodular opacity on chest X-ray. During bronchoscopy and macroscopic examination, the tumour appeared as polypoid and reddish and was located in a lobar bronchus. Insignificant size change over two years and lack of complications (post-obstruction pneumonia or atelectasis) indicated low malignancy which was confirmed by the histological report on the specimen. Diagnosis was made by transbronchial biopsy, which is considered to be an appropriate procedure for similar cases and without great risk of substantial haemorrhage,12 although in this instance infusion of adrenaline saline was needed.

 

 Differential diagnosis is required from other primary lung tumours. Low malignancy mucoepidermoid tumours must be distinguished from bronchial mucous adenoma, whereas high malignancy tumours are often confused with adenosquamous carcinoma.14

 

 Low malignancy tumours are usually localized and have a low risk of local lymph node metastasis, about 2%.7 Metastasis to other organs is rare but individual cases of skin,15 brain,16 and pleural fluid17 metastasis have been reported. Almost all mucoepidermoid carcinomas in children or young adults are of low malignancy.18

 

The treatment of choice is surgical removal and the prognosis is very good, with a 67% 10-year survival in the case of centrally localized tumours.19 On the contrary, tumours located peripherally have a decreased 4-year survival of 20%, as do high malignancy tumours.20 Radiation therapy is adjuvant and confined to cases of partial removal or recurrence, and in cases of metastastic disease.14

 

References

 

1. Moran CA. Primary salivary gland-type tumours of the lung. Semin Diagn Pathol 1995, 12(2): 106-22.

2. Segletes LA, Steffee CH, Geisinger KR. Cytology of primary pulmonary mucoepidermoid and adenoid cystic carcinoma. A report of four cases. Acta Cytol 1999, 43(6): 1091-7.

3. Heitmiller RF, Mathisen DJ, Ferry JA, Mark EJ, Grillo HC. Mucoepidermoid lung tumours. Ann Thorac Surg 1989;47(3):394-9.

4. Miller DL, Allen MS. Rare pulmonary tumours. Mayo Clin Proc 1993, 68(50: 492-8.

 5. Shanmugaratham K. Histological typing of tumours of the upper respiratory tract and ear. 2nd edition. International Histological Classification of Tumours. Berlin:World Health Organization, 1991: 35-6.

 6. Seifert G, Sobin LH: The World Health Organization’s histological classification of salivary gland tumours. A commentary on the second edition. Cancer 1992, 70: 379-385.

7. Yousem SA, Hochholzer L. Mucoepidermoid tumours of the lung. Cancer 1987, 60: 1346-52.

 8. Thomas V. Colby, Michael N. Koss, William Travis. “Tumours of salivary gland type” In: Tumours of the lower respiratory tract, AFIP, 1994, p65.

 9. Kim TS, Lee KS, Han J, Im JG, Seo JB, Kim HY, Han SW. Mucoepidermoid carcinoma of the tracheobronchial tree: radiographic and CT findings in 12 patients. Radiology 1999, 212: 643-8.

10. Green LK, Gallion TL, Gyorkey F. Peripheral mucoepidermoid tumour of the lung. Thorax 1991, 46: 65-6.

11. Vadasz P, Egervary M. Mucoepidermiod bronchial tumours: a review of 34 operated cases. Eur J Cardiothorac Surg 2000, 17(5): 566-9.

 12. Yang CS, Kuo KT, Chou TY, Lin CM, et al. Mucoepidermoid tumours of the lung: analysis of 11 cases. J Med Clin Assoc 2004;, 67(11): 565-70.

13. Chetty R, Forder MD, DeGroot M.. Muco-epidermoid and adenoid cystic carcinomas of the trancheobronchial tree. Aust NZ J Surg 1991, 61: 360-362.

 14. Jubith Luce. “Lymphoma, lymphoproliferative diseases, and other primary malignant tumours” In: J.F. Murray, J.A. Nadel Textbook of Respiratory Medicine, 3rd edition, W.B. Saunders, 2000, p.1453.

15. Yen A, Sanchez RL, Fearneyhough P, Tschen J, Wagner RF Jr. Mucoepidermoid carcinoma with cutaneous presentation. J Am Acad Dermatol 1997, 37: 340-2.

16. Wolf KM, Mehta D, Claypool WD. Mucoepidermoid carcinoma of the lung with intracranial metastases. Chest 1988, 94: 435-8.

17. Matsushita I, Takeda T, Kobayashi TK, Tanaka B, Sawaragi I. Mucoepidermoid carcinoma of the salivary gland in pleural fluid. A case report. Acta Cytol 1983, 27: 525-8.

 18. Welsh JH, Maxson T, Jaksic T, Shahab I, Hicks J. Tracheobronchial mucoepidermoid carcinoma in childhood and adolesence: case report and review of the literature. Int J Pediatr Otorhinolaryngol 1998, 45: 265-73.

 19. Chen F, Tatsumi A, Miyamoto Y. Succesful treatment of mucoepidermoid carcinoma of the carina. Ann Thorac Surg 2001, 71(1): 366-8.

 20. Shimizu J, Watanabe Y, Oda M, Morita K, Tsunezuka Y, Nonomura K. Clinicopathological study of mucoepidermoid carcinoma of the lung. Int Surg 1998, 83: 1-3.

References