Mixed seromucinous glands are present in the trachea and large bronchi and can lead to a variety of salivary-gland like tumors. The major types of these are mucoepidermoid, adenoid cystic and epithelial-myoepithelial carcinoma.
Patient is a 64 year old male with history of smoking and heavy alcohol use but no other known past medical history who presented with the complaint of right upper quadrant pain which worsened with deep inspiration and swallowing. Review of symptoms was only positive for a 20 pound unintentional weight loss over the past 6–12 months. Chest radiograph demonstrated a right lower lobe consolidation. Patient was started on antibiotics but clinically decompensated and was intubated due to respiratory failure and subsequently required vasopressors for septic shock. CT of the chest (figure 1) demonstrated a right lower lobe abscess filled with GI contrast; findings concerning for a broncho-esophageal fistula. EGD was performed which showed a large, horseshoe-shaped friable mass in the midesophagus with a fistula communicating with the abscess in the RLL. Purulent material from the abscess was cultured and grew Candida albicans. Biopsy of the esophageal mass was consistent with poorly differentiated adenocarcinoma, favoring esophageal primary. Cardiothoracic surgery was consulted and it was determined that there were so surgical options. Prognosis was discussed with the patient’s family and the decision was made to withdraw all supportive care. Autopsy showed that the final histology was an 8cm in diameter high-grade mucoepidermoid carcinoma. The tumor involved the peripheral RLL and 60–70% of the circumference of the mid-esophagus, with extension into the esophageal lumen. The tumor was adherent to the outer portion of the thoracic aorta and was directly invading lymph nodes in the right peri-hilar area (figure 2). Metastatic lesions were found in the right adrenal gland. No low grade component of tumor was found making primary site of origin difficult. Stains were positive for CK7 and negative for TTF-1. Overall findings favored a lung primary.
Mucoepidermoid carcinoma of the bronchus is a rare primary lung malignancy comprising 0.1–0.2 percent of lung cancers and has no association with tobacco use. It is characterized by a combination of mucin-secreting, squamous and intermediate cell types. Patients range from 3 to 78 years, half less than 30. Given the characteristic endobronchial location, patients often present with wheezing, cough, hemoptysis and postobstructive pneumonia/recurrent pneumonia. Histologically these tumors are divided into low- and high-grade types. In low-grade tumors there is minimal pleomorphism, rare mitosis, rare parenchymal invasion and minimal necrosis. High-grade tumors have increased mitosis, necrosis and nuclear pleomorphism. High-grade tumors are associated with an older population and carry a worse prognosis, as they tend to behave clinically similar to the more common non-small cell carcinomas. High-grade tumors can be difficult to distinguish from adenosquamous tumors, especially if there is no transition zone from low-grade tumor cells, which is why some cases can be misdiagnosed with endoscopic biopsy. Mucoepidermoid tumor cells are typically TTF-1 and CK20 negative, CK7 positive and often CK5/6 positive. Treatment of choice is surgical resection.
Mucoepidermoid carcinoma is a rare primary lung cancer. Symptoms at presentation are often related to endobronchial obstruction. This diagnosis must especially be considered in younger patients without risk factors for lung cancer. Prognosis is good if localized tumor is resectable.
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