National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran TANAFFOS (Respiration) 1735-0344 24 3 2025 07 01 From Cystic Lung Lesions to Pulmonary Lymphangio-leiomy­oma­to­sis: A Case-Based Diagnostic and Therapeutic Approach 303 308 739082 EN Mohsen Sadeghi Chronic Respiratory Diseases Research Center (CRDRC), National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran Inflammatory Lung Disease Research Center, Department of Internal Medicine, Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran Fatemeh Sadat Hosseini Khajouei Student Research Committee, Arak University of Medical Sciences, Arak, Iran Amir Morteza Soleimani Department of Internal Medicine, School of Medicine, Arak University of Medical Sciences, Arak, Iran Clinical Research Development Unit of Amiralmomenin Hospital, Arak University of Medical Sciences, Arak, Iran 0000-0003-0236-8258 Journal Article <strong><span lang="EN-US">Background:</span></strong><span lang="EN-US"> Lymphangioleiomyomatosis (LAM) is a rare, progressive cystic lung disease that primarily affects women of reproductive age. It arises from abnormal proliferation of smooth muscle-like cells, resulting in cystic lung remodeling, impaired airflow, and recurrent pneumothorax. Serum vascular endothelial growth factor D (VEGF-D) can support diagnosis, but normal levels do not exclude the disease.</span><br><strong><span lang="EN-US">Case Presentation:</span></strong><span lang="EN-US"> We describe a 37-year-old woman with six months of progressive dyspnea and hypoxia (SaO₂: 86%). High-resolution CT revealed diffuse, thin-walled cystic lesions. VEGF-D levels were within the normal range. Pulmonary function tests showed moderate obstructive impairment (FEV₁ 61%, FEV₁/FVC: 64%) and reduced diffusing capacity (DLCO: 45%). Transbronchial lung biopsy confirmed LAM with HMB-45 positivity. Sirolimus therapy was initiated in response to symptomatic impairment. </span><br><strong><span lang="EN-US">Conclusion: </span></strong><span lang="EN-US">This case shows that normal VEGF-D levels do not rule out LAM. Histopathologic confirmation remains essential when clinical and imaging findings are suggestive. Timely diagnosis enables initiation of mTOR inhibitor therapy, which can help stabilize lung function, manage cystic lesions, and inform decisions about further interventions, including lung transplantation.</span> https://www.tanaffosjournal.ir/article_739082_f6b3882d0c76344d57dac5d5248d7823.pdf