Bronchial Mucoepidermoid Carcinoma Misdiagnosed as Adenocarcinoma: A Word of Caution

Tracheobronchial mucoepidermoid tumors (METs) typically occur in the head and neck region but rarely in the trachea and lung. They are salivary-type tumors that arise from the glandular component of the tracheobronchial epithelium. The most common type, mucoepidermoid carcinoma (MEC) has histological features that overlap with more aggressive lung carcinomas such as adenosquamous carcinoma. It is important to realize the histological features and limitations of a diagnostic biopsy. This case illustrates this point where an initially diagnosed lung adenocarcinoma turns out to be MEC. We report a case of a 43-year-old woman with a one-year history of recurrent episodes of cough and fever. Initial bronchial biopsy diagnosed her as having adenocarcinoma of the lung. However, her surgical biopsy confirmed it was MEC. High clinical suspicion that the diagnosis may not have been correct saved her from a potential pneumonectomy. She instead underwent bi-lobectomy sleeve resection. This case illustrates the importance of recognizing less common and less aggressive lung tumors that may appear histologically as adenosquamous carcinoma. High clinical suspicion, not only biopsy results, from clinical history, imaging and gross appearance is always needed in all cases. The use of intraoperative frozen section is mandatory. It is important to be aware that because of morphological limitations of small endobronchial biopsies, diagnosis of a more common pathology may be favored.