Pleomorphic adenomas commonly involve major salivary glands, parotid and submandibular glands being the most frequent locations. Involvement of the trachea and bronchi is rare, and to the best of our knowledge 41 cases have been reported.1 Although most of these adenomas are considered benign, malignant transformation with metastases to the lung parenchyma and chest wall have been described.2 Middle-aged men or women are most commonly affected; symptoms are not specific and, as with other tracheal tumors, could simulate asthma.3,4 Prognosis is not well defined because of its potential for mitosis and the paucity of data describing its behavior.5 Recommended management includes surgery or resection by means of bronchoscopy.6 We report a case of a pleomorphic adenoma of the trachea that was resected with argon plasma coagulation and subsequent early follow-up biopsies at 15 days and 8 months.
A 33-year-old woman with complaints of productive cough, whizzing, and occasional hemoptysis was being treated for asthma for the past 4 years. Her chest roentgenogram and spirometry were unremarkable. Computed tomography (CT) of the thorax showed a tumor confined to the inner trachea, in its upper third (Fig. 1). Flexible bronchoscopy (FB) performed under conscious sedation revealed a lobulated, vascularized sessile tumor arising from the right lateral wall of the upper trachea occluding approximately 80% of its lumen (Fig. 2A). A therapeutic FB was performed in the operating room under general anesthesia, having rigid bronchoscope available if required. Initially, an ultrathin bronchoscope (Olympus XP-160 F Optical Co. Ltd., Tokyo, Japan) was passed beyond the tumor for estimating the length of the lesion. Subsequently, through a 6 mm outer diameter bronchoscope (Olympus BF-1T180, Optical Co., Ltd.), argon plasma coagulation of the lesion was carried out after obtaining the endobronchial biopsy. Near total patency of the tracheal lumen was established. (Fig. 2B). Histopathologic examination revealed pleomorphic adenoma of the trachea (Fig. 3).
Repeated bronchoscopies were performed at day 15 and at 8 months using narrow band imaging (NBI) guidance and endobronchial biopsies were obtained. No vascular abnormalities suggestive of neoplastic process were seen on the NBI and the biopsy finding revealed only inflammatory changes.
Primary tumors of the trachea correspond to 0.2% of all airway neoplasms, affecting 0.1/100,000 individuals per year. Ninety percent of these lesions in adults are malignant,7 squamous cell carcinoma and adenoid cystic carcinoma being the commonest.8 The most frequent benign tracheal tumors are papilloma, fibroma, hamartoma, and hemangioma.9 Pleomorphic adenomas of the trachea are rare benign neoplasms. Macroscopically, they have a grayish appearance and a firm consistency, most being sessile and located in the lower third of the trachea and main carina.3
Microscopically, glandular and myoepithelial cells with chondromyxoid stroma and central pseudoinvasion are characteristics. Its slow rate of growth is responsible for the insidious clinical course, with symptoms such as cough, stridor, dyspnea, whizzing, and hemoptysis. Dyspnea is reported as the main complaint,8,10 and patients are often misdiagnosed as having asthma.3,4,11 Pulmonary function testing with the flow volume loop could be helpful in suspecting the tracheal lesion,4 but in the present case, spirometry was normal. Chest roentgenograms are not helpful because tumors are rarely visualized.11 CT and magnetic resonance images of the thorax have a diagnostic yield of up to 90%, also allowing for the evaluation of near and distant structures. Some authors recommend both studies in the differential diagnosis of asthma, especially if an adequate response to treatment was not achieved.3,11,12
FB remains as the gold standard for diagnosing tracheal tumors. A precise evaluation of tumor characteristics, localization, and extension is made by the bronchoscopic examination, along with the possibility of biopsy sampling. Both CT and bronchoscopy play a central role in diagnosis and treatment planning.
Treatment of tracheal tumors initially involves resection to alleviate airway obstruction and respiratory distress, if present. It could be made by surgery or bronchoscopy, whether rigid or flexible.13 Evidence for the definite treatment of tracheal tumors, which rely on single-institution series and epidemiological studies, mainly applies to squamous cell carcinoma, adenoid cystic carcinoma, and other malignant tracheal neoplasms. It seems that there are enough data suggesting a better survival after surgical resection when compared with nonsurgical treatment for all malignant neoplasms of the trachea, even if resection margins are close.7 Thus, approach focuses on who might be amenable for surgical resection and who may not, reserving endoscopic techniques for palliation or acute relief of obstruction.11
Benign tracheobronchial adenomas have a good prognosis when surgically resected.9 Endoscopic resection has also been proposed as curative treatment while using a proper technique and when limited to those tumors with endoluminal growth and a small implantation base.14 In the presented case, no extraluminal growth was evidenced by CT and endoscopic resection was feasible.
Malignant transformation of pleomorphic adenoma has been described in 2 case reports10 and is probably the main reason for suggesting surgery as the only potentially curative treatment. Even though long-term follow-up after endoscopic resection has not been provided, along with the paucity of data, endoscopic techniques as a treatment option cannot be precluded. Endoscopic resections by laser or argon plasma coagulation followed by careful observation have been reported with good results.6,14 An understanding of the role of endobronchial ultrasound and NBI in the staging and follow-up of these tumors is currently lacking.
Pleomorphic adenoma of the trachea is considered a rare tumor. As with other tracheal tumors, obstructive respiratory symptoms could mimic asthma and cause a delay in the diagnosis. CT and FB help in confirming the diagnosis and treatment planning. Surgical resection is considered the treatment of choice; however, less-invasive endoscopic resection with careful observation could also serve as a treatment option.
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