Case Presentation: A 56-year-old man with a medical history of nicotine dependence, gastroesophageal disease (GERD) and chronic obstructive pulmonary disease (COPD) emphysema sub-type presented to the outpatient clinic for the evaluation of cough and shortness of breath. Cough was said to be productive of light-yellow sputum and he denied any associated fevers or chest pain. Pulmonary function test (PFT), alpha-1 antitrypsin (AAT) level and a CT scan of the chest were ordered. AAT level was normal while his PFT showed reduced FEV1- 45% of predicted and a reduced postbronchodilator FEV1/FVC ratio of 0.5. CT chest revealed bullous emphysematous changes of the right lower lobe and fibrosis with traction bronchiectasis in both left and right upper lobes. Further evaluation of the CT chest also revealed dilated trachea measuring about 3.5cm. Patient was counselled on the findings on the CT scan. In addition to his albuterol rescue inhaler, he was also continued on tiotropium inhaler and budesonide-formoterol combination inhaler. Patient continues to desire to smoke. He is currently being managed in a multidisciplinary team and remains under close follow up.
Discussion: Mounier Kuhn syndrome (MKS) is a very rare constellation of signs and symptoms that arise usually from what is believed to be congenital tracheobronchial dilatation. It is a rare clinical entity, with only about 200 cases reported since it was first described in 1932. There is no age predilection, but it is usually diagnosed around the 3rd decade of life with a relatively higher prevalence in African Americans. This is contrary to our Hispanic patient who was diagnosed in the 6th decade of life. Similar to our patient however, there is an increased prevalence in smokers, and it affects males more than females in a ratio of 8:1. There appears to be some emerging controversy regards the etiology. However, it is believed to be mostly congenital as specific histopathological findings of thin muscular mucosa, atrophy of the muscle and elastic fibers together with a history of recurrent childhood infections appear consistent across board for many of the cases reported in literature. A diagnosis of MKS is made when the diameter of the trachea is ≥ 3cm, right mainstem ≥ 2.5cm and left mainstem ≥ 2cm. Clinically, non-specific respiratory symptoms are usually present and features suggestive of GERD may be present. Imaging findings of emphysema may also be present, as in our patient. Smoking cessation, supportive therapy with mucolytics and physical therapy remain the mainstay of management.
Conclusions: A high index of clinical suspicion is required to make a diagnosis of MKS. Although treatment is mainly supportive, some subgroup of patients particularly those with recurrent infections might benefit from earlier diagnosis; to prevent the sequalae of recurrent infections. To the best of our knowledge, this is the first report of MKS in an individual of Hispanic origin.