B46-11 Chylothorax in PIK3CA-missense Mutated Central Conducting Lymphatic Anomaly

Introduction Chest cavity exudate in Central Conducting Lymphatic Anomaly (CCLA) is challenging for treatment where lymphatic vessel embolization is not possible. The genetic diagnosis of CCLA is challenging due to the mosaic characteristics of the mutation. Here we present a patient where a multidisciplinary approach and international collaboration have allowed us to reach control over chylothorax in the patient with genetically verified CCLA. Description of the case report Eighteen y.o. female Caucasian with no history of smoking, BMI 14-15, reporting symptoms of ill-being for 5 years prior to seeking help including left hemithorax pain, difficulty with deep breathing. Multiple contacts with healthcare over several months resulted in symptoms misdiagnosed as anxiety. ​After several admissions to emergency care with nausea, fever, vomiting, abdominal pain, the diagnosis of left-sided chylothorax with gradual build-up of chylothorax on the right side was established. Several attempts of drainage failed due to recurrent chylothorax. PET-CT with no findings of malignancy, neither in pleural effusions.CT lymphangiography and intranodal lymphangiography with lipiodol showed findings compatible with a congenital disorder of the central lymphatic circulation with slow transport of lymph from the groin, reflux of contrast in partially dilated saccular lymphatic channels in the pelvic area and in the abdomen (picture 1). There was a leakage into the left pleura, and the same thing was likely also present on the right side. The leakage was not technically available for embolization. Surgery performed: right VATS with ligation of thoracic duct and total pleurectomy 2025-05-20​, left VATS with ligation of thoracic duct and total pleurectomy, wedge excision basal dorsal left lower lobe 2025-05-27. ​Postoperative period with long hauling pneumothorax and excessive production of chylothorax. PleurX bilaterally, discharged home with Sirolimus treatment and Propranolol.Lately, admitted with bilateral empyema, gram positive streptococcus group A. IV antibiotics, pleurolysis bilaterally with good effect. After CT scan without pleural effusions, pleurX were taken out. PIK3CA missense mutation (mosaicism) in affected tissues has been shown. Middle chain triglycerides diet in combination with very low-fat diet has led to weight gain. Blood albumin is normalized. Add-on Alpelisib treatment is considered. Discussion of the novelty and importance of the case Suspected chylothorax in young adults should be approached systematically. Treatment options in correctly verified lymphatic malformations are available. Careful diagnostics including imaging of the lymphatic vessels and human genetic examination are of utmost importance which is demonstrated in that case of successful treatment of CCLA.Picture 1. Pelvic lymphangyography. This abstract is funded by: None