Cystic Lung Disease Presenting as Recurrent Non-traumatic Chylothorax: Case Report and a Mini-Review.

Malignancy and infections are the most common causes of recurrent chylothorax. Cystic lung disease, especially sporadic pulmonary lymphangioleiomyomatosis (LAM), is a rare condition that may manifest as recurrent chylothorax. We present a case of a 42-year female who presented with dyspnea on exertion secondary to recurrent chylothorax, requiring three thoracenteses within a few weeks. Chest imaging showed multiple bilateral thin-walled cysts. Thoracentesis revealed milky-colored pleural fluid, which was exudative and lymphocytic predominant. Infectious, autoimmune, and malignancy workup was negative. Vascular endothelial growth factor-D (VEGF-D) levels were sent for testing, which came back elevated (2001 pg/ml). A presumptive diagnosis of LAM was made based on recurrent chylothorax, bilateral thin-walled cysts, and elevated VEGF-D levels in a reproductive age group woman. Given quick reaccumulation of chylothorax, she was started on sirolimus. After initiating therapy, there was a significant improvement in the patient's symptoms, with no recurrence of chylothorax in the five years of follow-up. Awareness of different forms of cystic lung diseases is vital to establish an early diagnosis, which may prevent disease progression. Rarity and heterogeneity of presentation often make the diagnosis challenging, requiring a high degree of suspicion.