This is a prospective, open, non-comparative and baseline-controlled study to evaluate efficacy and safety of Macrolane VRF20 treatment in 40 subjects with pectus excavatum deformity.

Each subject participating in the study will be treated with approximately 50-150 ml of Macrolane VRF20. The amount of study product used will be individually determined in order to achieve an optimal correction of the deformity in each subject.

Inclusion Criteria:

1. Give verbal and written informed consent to participate in the study.
2. Be a healthy male of 18 years or more.
3. Have a pectus excavatum deformity without functional problems; score 4 in items 10, 11 and 12 of the PEEQ, indicating there is no functional impairment due to the pectus excavatum deformation.
4. Present normal cardiac function as assessed by ECG and echocardiogram.
5. Present normal pulmonary function as assessed by pulmonary function test.
6. Present a chest X-ray taken within 12 months prior to the baseline visit, without clinically significant defects to heart, lungs, skeleton, ribs, sternum or spinal cord except for the pectus excavatum defect, in the opinion of the Investigator.
7. Have the ability to understand and comply with the requirements of the study.

Exclusion Criteria:

1. Score 1, 2 or 3 in either of items 10, 11 and 12 of the PEEQ, indicative of functional problems due to the pectus excavatum deformity.
2. Previous treatment for the same indication.
3. Known or suspected hypersensitivity to hyaluronic acid based products.
4. BMI < 20.
5. A history of severe allergies manifested by a history of anaphylaxis, or a history or presence of multiple severe allergies (as judged by the Investigator).
6. Known allergy to any anesthesia planned during the study.
7. Presence of autoimmune disease or other chronic disease that in the opinion of the Investigator may interfere with the outcome of the study.
8. Subjects with bleeding disorders or subjects who are taking thrombolytics or anticoagulants, or have taken inhibitors of platelet aggregation, including non-steroidal anti-inflammatory agents and acetylsalicylic acid, two weeks before treatment.
9. Subjects on immunomodulatory therapy (suppressive or stimulatory).
10. Subjects with contraindications for MRI, such as presence of pacemaker, clips or splinter, or tendency for claustrophobia.
11. Any condition which in the opinion of the Investigator makes the subject unsuitable for inclusion (e.g., subjects not likely to participate for the duration of the study).
12. Use of any investigational drugs or devices within 30 days prior to baseline.
13. Subjects who are study site staff for this study, or close relatives of the study site staff, as well as subjects who are employed by the Sponsor company, or close relatives of employees at the Sponsor company.