First Case Report of Metastatic Squamous Cell Carcinoma of Lung Associated with Mounier-Kuhn Syndrome and Review of Literature.

Mounier-Kuhn syndrome is a relatively rare condition, mostly involving the trachea and main stem bronchi. It is caused either by the atrophy of elastic fibers or faulty fetal development of cartilage and smooth muscles, hence leading to an overall increase in the diameter of lower respiratory tract. No certain etiology was found in the majority of cases reported previously, however, several other connective tissue diseases have also been implicated with the congenital tracheobronchomegaly. One anecdotal case report mentioned the development of lung malignancy in a patient who had previously received external beam radiotherapy. Herein, we report the first case of Mounier-Kuhn syndrome in a 62-year-old male with a recent diagnosis of metastatic squamous cell carcinoma (SCC) of the lung.