Pulmonary lymphangioleiomyomatosis (PLAM) is a rare clinical disease that can occur sporadically or in association with the genetic disorder tuberous sclerosis complex (TSC). Sporadic PLAM almost exclusively affects women of childbearing age. Pathologically, it is characterized by diffuse or nodular proliferation of smooth muscle-like cells (LAM cells, HMB-45+) in the alveolar walls, bronchiolar walls, and vascular walls, leading to localized pulmonary emphysema or the formation of thin-walled cysts.
Clinically, PLAM primarily presents with progressively worsening dyspnea, recurrent pneumothorax, and chylothorax, with occasional hemoptysis. Pulmonary function tests typically show airflow obstruction and impaired gas exchange, with restrictive ventilatory dysfunction occurring in advanced stages. On high-resolution computed tomography (HRCT), the characteristic finding is diffusely distributed, relatively homogeneous, thin-walled cysts (2-20 mm in diameter) throughout both lungs. The key difference between PLAM and PLCH on CT is that PLCH generally spares the costophrenic angles, has thicker and more irregular cyst walls, and is associated with more nodules in the early stages of the disease.
Currently, there is no cure for PLAM that can reverse disease progression. Recent studies have shown that the immunosuppressant sirolimus can stabilize or improve lung function in some patients. For end-stage PLAM, lung transplantation may be considered.