Abstract
Cystic hygroma is a rare congenital anomaly typically observed in newborns, with cases in adults being exceptionally rare. In adults, these lesions often remain asymptomatic and present unique challenges owing to the absence of established treatment protocols. This report describes a 23-year-old male with a large pulmonary cystic hygroma manifesting as progressive chest discomfort, breathing difficulties, and systemic symptoms. Diagnostic imaging revealed an extensive cystic structure within the mediastinal-pulmonary region, which was managed surgically via cystotomy. Histopathological analysis confirmed the diagnosis, and the patient experienced a complete recovery with no recurrence during follow-up. This case highlights the need for standardized guidelines in the management of pulmonary cystic hygromas and emphasizes the importance of including cystic hygroma in the differential diagnosis of pulmonary masses in adults. Further studies are essential to optimize therapeutic approaches and enhance outcomes for adult patients with this rare condition.