Could a daily dab of sirolimus ease tongue cysts?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Participants ≥ 5 years of age * Lingual microcystic lymphatic malformation that does not require systemic treatment, assessed by clinical examination and head-and-neck MRI imaging prior to study enrolment, with or without underlying syndromic malformation (CLAPO for instance) * Participants covered by or having the rights to social security * Written informed consent obtained from participant and participant's legal representative if participant is under 18 * Ability for participant to comply with the requirements of the study Exclusion Criteria: * Patients with a lymphatic malformation requiring a continued background therapy (involving deep organs) * Secondary lymphatic malformations (lymphangiectasia post-radiotherapy, etc) * Previous treatment with systemic or topical mTOR (mammilian target of rapamycin) inhibitors within 12 months before inclusion (half-life of oral sirolimus is 60 days in adults). * Previous treatment with oral or topical steroids within 10 days before inclusion (half-life of corticosteroids is 12-36 hours) * Immunosuppression (immunosuppressive disease or immunosuppressive treatment) * Ongoing neoplasia * Active chronic infectious disease (Hepatitis-B virus, Hepatitis-C virus, HIV, etc) * Local necrosis * Local fungal, viral (herpes simplex virus, varicella zoster virus, etc) or bacterial infection on the site of the LMLM (based on clinical examination) * Known allergy to one of the components of the sirolimus solution * Soy bean or Peanut allergy * Pregnant or breastfeeding women * Women of child-bearing potential (including teenagers) not using a reliable contraceptive method until the end of the study and three month after the end of the study or sirolimus discontinuation. * Already involved in another therapeutic trial