EP06.49: Prenatal detection of large complicated lympho‐venous malformation: effective and safe maternal sirolimus treatment

Congenital lympho-venous malformations (CLVMs) are rare vascular anomalies which may be life-threatening due to large size, location, or intralesional bleeding. CLVM diagnosis is possible in fetal ultrasonography, however prenatal sirolimus treatment has been reported in only two cases to date. The mTOR inhibitor, sirolimus, is an immunosuppressant with antiangiogenic properties and has been successfully given off-label in lymphatic and venous malformations. Massive CLVM involving abdomen, pelvis, buttocks and left lower limb was detected in second trimester screening. Intralesional bleeding during 32nd week of pregnancy caused the fetus' anemia manifested by increased MCA PSV (59-77cm/s, 1.3-1.7 MoM) and prompted decision to introduce off-label maternal oral sirolimus following the Consent of Independent Bioethics Committee and mother's informed written consent. Sirolimus treatment with regular ultrasonography examinations were continued until Caesarean section in 37th week of pregnancy. Sirolimus dose 4 mg/day resulted in serum level of 6,4 ng/mL at delivery and 4,2 ng/mL in umbilical cord blood. MCA PSV significantly decreased within 2 days of sirolimus treatment. No adverse events occurred. The child has continued sirolimus postnatally with CLVM reduction. Prenatally diagnosed fetal high-risk CLVMs may be effectively and safely treated with material sirolimus with serum drug levels' monitoring. This novel option of prenatal CLVMs' therapy is available in Poland thanks to interdisciplinary cooperation between pediatric oncology vascular anomalies' team, neonatology, and obstetrics departments. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.