Enlarging cystic lymphangioma of the mediastinum in an adult: is this a neoplastic lesion related to the recently discovered PIK3CA mutation?

Cystic lymphangioma, a lymphatic system malformation, is usually observed in infants and children and is rarely found in adults. It most commonly occurs in the cervicofacial region, followed by the axilla. Mediastinal cystic lymphangioma is rare, accounting for 1.8% of all mediastinal cysts. Herein, we present an exceedingly rare adult case of mediastinal cystic lymphangioma that had increased in size over a 5-year period. Although fluid collection might be an alternative explanation for this increase in size, this lymphangioma might harbor a neoplastic nature related to the recently discovered PIK3CA mutation.