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Bronchial Mucoepidermoid Carcinoma With the Classic MAML2 Gene Rearrangement in a 2-year-old Boy

Pulmonary mucoepidermoid carcinoma (PMEC) is rare. To date, primary PMEC has not been reported in a child younger than 3 years of age. We report a case of a 2-year-old boy who presented with 3 episodes of wheezing, cough, and fever over a period of 1 month. Radiologic findings were consistent with foreign body aspiration with consequent bronchial obstruction. Bronchoscopy was performed and attempts to retrieve the foreign body resulted in a biopsy of a fleshy lesion. By histology, the lesion was an epithelial neoplasm comprising cells arranged in a nested pattern. The neoplastic cells were round with round nuclei and amphophilic, vacuolated cytoplasm. Our diagnosis was low-grade salivary gland-type carcinoma of the bronchus. The pneumonectomy specimen showed a well-circumscribed, polypoid intrabronchial mass measuring 2.1 cm in greatest dimension. Histologic examination of the tumor showed an admixture of intermediate cells which were predominant, a small number of mucus cells and rare foci of squamous cells. The final diagnosis rendered was a low-grade mucoepidermoid carcinoma of the bronchus. Accurate diagnosis of PMEC can be challenging on limited biopsy material as seen in the case reported here. The use of molecular studies such as MAML2 gene rearrangement may facilitate diagnosis in difficult cases. Increased awareness of this entity and further molecular studies are needed for a better understanding of the pathogenesis of PMEC. To date, the reported age range for primary bronchial mucoepidermoid carcinoma is between 3 years and 78 years. This case represents the youngest patient reported in the English literature.