Clinical-radiological, histological and genetic analyses in a lung transplant recipient with Mounier-Kuhn syndrome and end-stage chronic obstructive pulmonary disease

Mounier-Kuhn Syndrome Mimicking Lymphangioleiomyomatosis

We present the case of a man with Mounier-Kuhn syndrome (MKS), or tracheobronchomegaly, who was referred to the National Institutes of Health Clinical Research Center because of a potential diagnosis of lymphangioleiomyomatosis (LAM), a rare condition in men. The patient was evaluated using ongoing protocols and provided written informed consent. The case demonstrates the presence of chronic inflammation surrounding the dilated airways and histologic changes of the lung parenchyma with emphysematouslike disruption in areas adjacent to the dilated airways. This finding suggests that damage to the lung parenchyma is an ongoing phenomenon in MKS. Moreover, our analysis of CT images indicates similar abnormalities in areas remote from the dilated airways. Finally, because of increased anatomic dead space, calculation of lung diffusion capacity by the single-breath method yielded abnormally low values that required making a correction for the large anatomic dead space, which can be measured by the single-breath nitrogen washout test.

Mounier-Kuhn syndrome: a case of tracheal smooth muscle remodeling

Mounier–Kuhn syndrome is a rare clinical disorder characterized by tracheobronchial dilation and recurrent lower respiratory tract infections. While the etiology of the disease remains unknown, histopathological analysis of Mounier–Kuhn airways demonstrates that the disease is, in part, characterized by cellular changes in airway smooth muscle.

A Clinical Classification Scheme for Tracheobronchomegaly (Mounier-Kuhn Syndrome)

INTRODUCTION

Tracheobronchomegaly (Mounier-Kuhn Syndrome) is a rare disease characterized by tracheal enlargement and associated loss of elastic fibers in the trachea and main bronchi.

MATERIALS

MEDLINE, Index Medicus, and other databases were searched with pre-defined criteria to identify cases of tracheobronchomegaly (TBM). Two new cases of TBM were also identified from the Provincial Medical Genetics Program of British Columbia.

RESULTS

We identified 166 publications describing 365 occurrences of TBM. We observed that affected individuals could be grouped into subgroups according to clinical features. Type 1A (105 individuals) consists of infants who developed TBM after having undergone fetoscopic tracheal occlusion, and Type 1B patients (24 individuals) are infants and children who developed TBM after prolonged intubation. Type 2 individuals developed TBM following recurrent pulmonary infections (2A) (14 individuals) or pulmonary fibrosis (2B) (10 individuals). Type 3 represents TBM with evidence of extra-pulmonary elastolysis (18 individuals), and Type 4 denotes the development of TBM with no clear predisposing factors (196 individuals). Both of our patients had TBM and evidence of extra-pulmonary elastolysis. As well, one patient had a mildly dilated aortic root, which is a previously unreported co-occurrence.

CONCLUSION

We introduce a novel classification scheme, which may sort patients into etiologically distinct groups, furthering our understanding of its pathogenesis and potentially, prevention or therapy. We also hypothesize that TBM and generalized elastolysis may have etiological commonalities, suggesting a need for further study.