Here is the design of a clinical trial:

Official Title: 0.1% Topical Sirolimus in the Treatment of Cutaneous Microcystic Lymphatic Malformations in Children and Adults: Phase II, Split-body Randomized, Double-blind, Vehicle-controlled Clinical Trial

Included conditions:
- Vascular Malformations
- Lymphatic Malformation

Study Armgroups:
- {'label': 'Topical sirolimus', 'type': 'EXPERIMENTAL', 'description': 'The experimental group will consist in one area of the CMLM (almost half of it) that will receive 0.1% sirolimus preparation. This product will be applied 1/day on the randomly allocated area, by a nurse at home, during 12 weeks.', 'interventionNames': ['Drug: Topical 0.1% Sirolimus']}
- {'label': 'Vehicle', 'type': 'PLACEBO_COMPARATOR', 'description': 'The control group will consist in the other half area of the CMLM, that will receive the same vehicle than the one used in the topical 0.1% sirolimus preparation. It will be applied 1/day in the corresponding area by a nurse, at home, during 12 weeks.', 'interventionNames': ['Drug: Topical Vehicle']}

Interventions:
- {'type': 'DRUG', 'name': 'Topical 0.1% Sirolimus', 'description': 'The formulation is 0.03 g rapamycin, 1.5 g Transcutol, Quantum Satis (QS) 30g Excipial® hydrocream, corresponding to a concentration at 0.1%. The cream will be packaged in 30 ml aluminium tubes.', 'armGroupLabels': ['Topical sirolimus'], 'otherNames': ['Verum']}
- {'type': 'DRUG', 'name': 'Topical Vehicle', 'description': 'The same vehicle than the one used in the topical 0.1% sirolimus preparation will be used for the other half area of CMLM, i.e. Excipial® hydrocream. It will be packaged to maintain the double blind way of this trial and will be undistinguishable from the sirolimus cream.', 'armGroupLabels': ['Vehicle'], 'otherNames': ['Placebo']}

Primary Outcomes:
- {'measure': 'Efficacy of a 12-week application period of 0.1% topical sirolimus in cutaneous microcystic lymphatic malformation versus topical vehicle', 'description': 'PGA (Physician Global Assessment) score assessed by the investigator physician (blinded from the treatment). PGA score ranges from 0 (clear) to 5 (severe lesions), and is commonly used in several dermatologic conditions. For each patient, PGA of the area treated with the intervention (0.1% topical sirolimus) will be compared to PGA of the area treated with topical vehicle (inactive comparator)', 'timeFrame': 'Week 12'}

Please estimate the sample size based on the assumption: 
Assuming a power of 80%, a two-sided type I error rate of 5%.
Sample size
        The study is planned as a within-person design, which means that data from the two areas on a patient will be matched. In addition, the PGA score is an ordered score ranging from 0 (clear) to 5 (severe). Therefore, to estimate the sample size,Â we used an approach based on continuous data and a paired sample t test, assuming that the PGAÂ score difference (between the two areas) follows a normal distribution. Hypothesizing a 1-point difference and a 2.5-point standard deviation would lead to a 0.4 effect size. Assuming a power of 80%, a two-sided type I error rate of 5%, we will need to recruit 52 patients. We plan to recruit 55 patients.