This study has several parts and involves taking a study drug called alpelisib. Some participants enrolled into Stage 2 will receive a placebo for the first part of the study (24 weeks) and will then receive the study drug. The purpose of this study is to find out if the study drug is safe and effective (can help) people with a confirmed diagnosis of lymphatic malformation (LyM) and a documented mutation in the PIK3CA gene.

The purpose of this study is to see if a new investigational topical (applied to the skin) formulation of sirolimus, PTX-022 (the study drug), is safe and effective in treating participants with microcystic Lymphatic Malformations.

This study is for people with growing abnormal lymph vessels called lymphatic malformations (LMs). This study has 3 parts and involves taking a study drug called TARA-002. The purpose of this study is to find out if the study drug is safe and effective (can help) people with LMs. Participants receive the study drug by injection and will complete other research assessments throughout the study.