Clinicopathologic and genetic features of primary bronchopulmonary mucoepidermoid carcinoma: the MD Anderson Cancer Center experience and comprehensive review of the literature

Primary bronchopulmonary mucoepidermoid carcinoma (BPMEC) is a rare tumor. The fusion protein MECT1-MAML2 has been implicated as a causative genetic event in salivary and BPMECs. Several studies have shown the impact of MECT1-MAML2 on the diagnosis and prognosis of salivary gland mucoepidermoid carcinoma; however, few studies have been published regarding MECT1-MAML2 in the context of primary BPMEC. We describe the clinicopathologic, genetic, and outcome data of 16 patients with BPMEC. Clinicopathologic features were recorded from the electronic medical records. All tumors were reviewed by two expert pulmonary pathologists and graded according to previously established criteria. The presence of MECT1-MAML2 was evaluated with reverse transcription polymerase chain reaction using RNA extracted from formalin-fixed paraffin-embedded tumor tissue. Patients included 9 women and 7 men with a median age of 50 years (range, 7 to 82 years). Tumors exhibited low (n = 14, 88%), and high (n = 2, 12%) grade histologic features. Eight of nine tested tumors (89%) were positive for MECT1-MAML2. The median follow-up time was 40.8 months (range, 1.8-120). Median overall survival for patients with high-grade tumors was 12 months, which was significantly (p = 0.002) shorter than that for patients with low-grade tumors (survival undefined). We also provide a comprehensive review of literature of cases of primary bronchopulmonary mucoepidermoid carcinoma and summarize our findings in this context. MECT1-MAML2 fusion transcript is a driver genetic event in the pathogenesis of primary BPMEC. Histologic grade continues to play a pivotal role in the survival of patients with primary bronchopulmonary mucoepidermoid carcinoma.