Proteus syndrome in adulthood

Proteus syndrome is a very rare congenital condition comprising malformations and overgrowth of multiple sorts of tissue. It was described for the first time in 1979 and was termed Proteus syndrome in 1983. The authors describe a 37-year-old patient who was diagnosed initially as having Klippel-Trenaunay-Weber syndrome at the age of 10 years. The patient was operated for a major thoracic lymphatic malformation, which caused functional problems. The operation at older age for this large lymphatic malformation proved to be complex. In addition, the authors address the difficulties in diagnosing Proteus syndrome. Vascular malformations causing functional problems in adulthood require major surgical procedures with a high risk of postoperative complications.