Case report: Mucoepidermoid carcinoma in a patient with congenital agenesis of the left upper lobe.

This report describes an unusual case of a mucoepidermoid carcinoma developing in a patient with congenital left upper lobe agenesis. Mucoepidermoid tumours most often develop in major bronchi and present as lobar collapse, post-obstructive pneumonia or as a mass lesion on chest radiography. On CT, the tumour is smooth, well defined, homogeneous and may enhance with intravenous contrast. Tumour calcification has been reported. Lobar agenesis often presents as a co-incidental finding on chest radiography as total or almost complete absence of aeration of the affected lung. Thoracic CT confirms the presence of the underdeveloped lung, pulmonary artery and bronchus and associated mediastinal shift and herniation of the contralateral lung. A literature review of these two conditions is presented.