Abstract
Mesenchymal hamartomas of the chest wall are rare benign tumors. It has been known that the tumor temporarily grows after birth and the growth subsequently stops. We experienced two neonatal cases of mesenchymal hamartomas of the chest wall. Both cases were conservatively treated because radical resection would cause a large defect of the chest wall. The tumor enlarged until 6 months after birth, but the size has been decreasing one year after birth in both cases. In one case, the tumor was exposed from the incision site for biopsy due to rapid growth that required partial resection including MCT (microwave coagulation therapy) several times. At 6 months after birth, the tumor growth stopped and we were able to close the skin at 11 months after birth. In the other case, although the tumor temporarily enlarged, it did not cause any symptoms. The tumor size has been decreasing for three years. The clinical course of these cases suggests that asymptomatic mesenchymal hamartomas of the chest wall in infants should be conservatively treated, because they are benign and have the feature that the tumor spontaneously starts regressing within a year after birth.
