Mucoepidermoid tumors of the lung arise from tracheobronchial mucous glands and are similar in morphology to mucoepidermoid tumors arising from oropharyngeal salivary glands. They are extremely rare, composing 0.1-0.2% of primary lung cancers. A mixture of epithelial, mucin-secreting, and intermediate cells is seen microscopically. The biologic behavior depends on the histologic appearance; tumors with increased mitosis, necrosis and nuclear pleomorphism are considered high grade and are usually lethal. The majority are low-grade malignancies with a benign clinical course without recurrence or metastases (1).
A 65 year-old non smoker female presented with hemoptysis. She had a history of shortness of breath and cough for the previous 6 months. On physical examination, vital signs were normal except for a respiratory rate of 24 breaths per minute. There was diminished air entry with faint wheezing on the right side of the chest. The rest of the examination was unremarkable. Chest radiography showed right middle lobe collapse with a suspicion of adjacent mass. CT scan of the chest revealed an enlarged mass extending into the right main stem bronchus and the subcarina, enlarged right infrahilar mass with right middle and lower lobes atelectasis. Emergency bronchoscopy revealed a tumor arising from the medial wall of the right main stem bronchial orifice, obstructing the bronchus and involving the main carina (figure1). The histopathology of the tumor revealed low grade mucoepidermoid tumor. The patient was referred to our institution. We used Nd-YAG laser photo resection via flexible bronchoscope to control the bleeding and relieve the obstruction. Over the period of 6 months, we achieved excellent results with only a small residual tumor left behind (figure 2). The patient is currently asymptomatic and doing well.
In the past twenty years, the use of lasers for treating endobronchial disease has been tested and accepted as an important therapeutic modality for obstructive endobronchial or tracheal lesions. Although the primary role of laser resection in oncology patients is a palliative one, this technique may allow a prolonged survival when combined with other therapies as subsequent surgical excision and/or radiation therapy (2). Resection of the bronchus or a lobectomy with clear surgical margins in the absence of disease in the lymph nodes is usually curative in patients with low-grade mucoepidermoid tumors. One study showed long-term survival ranging from 5 to 23 years, averaging 12.8 years (3). In this patient, because of the location of the tumor and expected morbidity, surgery was not performed. One of the earliest series of bronchial adenoid cystic carcinoma (cylindroma) and mucoepidermoid carcinoma found that some patients had a prolonged survival and minimally associated morbidity, even when residual tumor was knowingly left behind (4).
Low grade mucoepidermoid tumors have excellent response to laser resection which is minimally invasive with low morbidity. Long term survival of these slowly growing tumors following laser resection is yet to be studied.
Jeffrey Nascimento, None.