Mucoepidermoid tumours (MEC), a type of salivary gland tumours, are one of the very rare neoplasms of the lung comprising <1% of all lung tumours [1]. They have an equal sex distribution with a slight predilection for men and have an age range of 3–78 years with 50% of tumours occurring in individuals <30 years. Most patients present in the third and fourth decade of life [1]. Here, we present such a rare case encountered during our clinical practice.

A 38-year-old lady presented with mild fever and dry cough of 1 week duration. Patient was treated for pulmonary tuberculosis 4 years ago. She was a non-smoker. There was no significant family history. Her chest X-ray showed right middle lobe collapse and consolidation with a mass in the right paracardiac region. CT thorax revealed a mass in the right middle lobe (Fig. 1a and b). Subsequent bronchoscopy showed a growth completely occluding the right middle lobe bronchus and extending proximally into the bronchus intermedius. Bronchoscopic biopsy was suggestive of myoepithelioma. A second opinion also raised the possibility of neuroendocrine tumour. Figure 1:

(a) Post contrast axial CT image shows well-defined heterogeneously enhancing lesion in right perihilar region causing displacement of pulmonary arteries. (b) Coronal reformed CT image shows the extent and vascular displacement.

MEC is a rare malignant tumour of bronchial tree. Its origin was first described in 1952 by Smetana and Liebow [2]. It accounts for <1% of all lung tumours [1]. This tumour has been reported to occur in relatively young persons. There appears to be no association with cigarette smoking or other risk factors for bronchial carcinoma such as asbestos exposure [3]. Our patient was a 38-year-old female, non-smoker.

MEC generally occurs in the central bronchial region. In our patient, the tumour was arising from middle lobe bronchus. The common clinical symptoms and signs include cough, haemoptysis, bronchitis, wheezing, fever, chest pain and rarely clubbing of the fingers [4]. Histologically these tumours are similar to those originally described in the major salivary glands and are believed to originate from the minor salivary glands lining the tracheobronchial tree [5].

Grossly, the tumour size at diagnosis ranges from 0.5 to 6 cm with an average size of ∼2.2 cm in the reported literature. They are soft, polypoid and pink-tan in colour, often with cystic changes and a glistening mucoid appearance [3].

On the basis of morphological and cytological features, tumours are divided into low and high-grade types. Low-grade tumours are dominated by cystic changes and solid areas typically comprising of small glands, tubules and cysts of mucin secreting and columnar epithelial cells with infrequent mitotic activity. Often non-keratinizing squamoid cells are also seen in a sheet-like pattern with intercellular bridges. High-grade MEC is very rare and show a predominance of intermediate and squamoid cells predominate with a minor component of mucin secreting elements. They demonstrate nuclear atypia with brisk mitotic activity and a high nuclear to cytoplasmic ratio [3].

The clinical picture of MEC is similar to that of asthma, COPD or pneumonia. Hence one should keep in mind of this rare entity in patients who are unresponsive to regular treatment. Low-grade MEC has a much better prognosis than high-grade tumour, the latter being similar to non-small-cell carcinoma [3]. Radical surgery similar to lung cancer treatment is performed for MEC. Patients with low-grade MEC have a good prognosis, with a 5-year survival rate of 95% and adjuvant treatment is unnecessary.

None declared.