CHEST Guidelines-Mounier-Kuhn-Syndrome-Mimicking-Lymphangioleiomyom

Mounier-Kuhn-Syndrome-Mimicking-Lymphangioleiomyom

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The document presents a case of Mounier-Kuhn Syndrome (MKS), also known as tracheobronchomegaly, mimicking lymphangioleiomyomatosis (LAM), which was diagnosed in a 40-year-old man. The patient had symptoms of recurrent low-grade hemoptysis and mild dyspnea. Initially suspected to have LAM due to CT scan findings that revealed tracheomegaly and cyst-like structures typically associated with LAM, further investigation through bronchoscopy and histopathologic examination confirmed the diagnosis of MKS. This syndrome is characterized by enlarged tracheobronchial airways and is associated with chronic inflammation and extracellular matrix breakdown, leading to emphysematous-like changes in both near and distant lung tissues.<br /><br />The case study highlights the potential for confusion between MKS and DCLD (Diffuse Cystic Lung Diseases) such as LAM, due to similarities in CT imaging. While LAM primarily affects women and involves smooth muscle cell infiltration of lung parenchyma, MKS involves tracheobronchomegaly with fibrotic changes. Accurate diagnosis in this case was achieved through comprehensive imaging, virtual bronchoscopy, and pathology confirmation of dilated airways rather than lung cysts. Additionally, the patient had an aspergilloma, a fungal mass, confirmed in a removed lung mass, also contributing to the diagnostic complexity.<br /><br />A significant finding in the study was the impact of large anatomic dead space on DLCO measurements, initially yielding abnormally low lung diffusion capacity for carbon monoxide. Correction for the enlarged tracheobronchial tree confirmed normal diffusion capacity, consistent with cardiopulmonary exercise test results. This correction method underscores the importance of considering anatomical variations in pulmonary function assessments.<br /><br />Ultimately, the case underscores the importance of a multidisciplinary approach combining imaging, phenotypic analysis, and histopathologic evaluation for the accurate diagnosis of rare pulmonary conditions such as MKS, preventing misdiagnosis and guiding appropriate management strategies.

Keywords

Mounier-Kuhn Syndrome

tracheobronchomegaly

lymphangioleiomyomatosis

hemoptysis

dyspnea

bronchoscopy

CT imaging

aspergilloma

DLCO

multidisciplinary approach