Swelling and hematoma due to facial contusion are one of the most common traumatic complications. Because swelling and hematoma are mostly absorbed by the observation, they are often not treated aggressively. However, if left untreated, hematoma can cause fibrosis. At that stage, cosmetic deterioration occurs, which can lead to psychological stress and social discomfort to the patients. Especially, hematoma develops often after facial contusion in patients taking anticoagulants, such as aspirin, clopidogrel, and warfarin for the prevention or treatment of heart or cerebrovascular disease, and unfortunately, conservative methods have their limitations. Hyaluronidase has the ability to break down the hyaluronic acid, facilitating the absorption of hematomas and edema through peripheral lymphatic channels and capillaries while the local intercellular permeability increase [1,2]. We report one case of hematoma and another case of fibrosis in which the patient’s clinical condition improved after administration of a hyaluronidase injection for the early treatment of hematoma or fibrosis after facial trauma.

Hematoma is a localized collection of coagulated and solidified blood from damaged vessels, caused by disease or trauma; it may lead to complications, such as poor wound healing, localized infection, and skin necrosis. Therefore, a more aggressive treatment is needed when hematoma is confirmed. Various methods have been tried to treat hematoma and fibrosis caused by trauma; however, no effective method have been identified [1]. Herewith, we report observing significant improvements in a patient with hematoma and another patient with fibrosis by hyaluronidase injection. Swelling, hematoma, pain, and the sensation of itching were improved in these patients who received hyaluronidase.

At the time of treatment, hyaluronidase injection was able to rapidly liquefy the solidified hematoma, causing rapid absorption and loss of hematoma. The treatment period was much shorter than that of massage or observation (in case 1, hematoma disappeared after 2 weeks of hyaluronidase injection). This has also prevented fibrosis from long-term wound hematoma.

Hyaluronidase has been shown to break down hyaluronic acid, which is the ground substance of the connective tissue, by separating 1,4-glucosaminidic bond between C1 and the glucosamine moiety and C4 of the glucuronic acid [3]. Treatment with hyaluronidase is effective owing to increases in the diffusion and absorption rate, which in turn, increases the intercellular permeability [1,4,5]. No complications were observed after treatment with hyaluronidase. Fibrosis after trauma occurs because of the activation of fibroblasts, resulting in increased collagen synthesis and accumulation of thin and disorganized collagen fibers [5,6]. It is generally known that hyaluronidase inhibits fibroblast proliferation [7].

We injected hyaluronidase directly into the fibrosis site, and it degraded hyaluronic acid to lower the concentration of the intercellular ground substance [1], hence improving the status of pain, pliability and stiffness on the fibrosis site. The improvement of fibrosis may be due to physical dissection by the needle itself during injecting hyaluronidase by the crisscross method which results in an increase in the spacing between the fibrotic tissues, and hence, the improvement of fibrosis. The effect of hydro dissection as well as the hyaluronidase itself may have influenced the improvement of fibrosis.

However, adhesiolysis using a needle without the hyaluronidase injection stresses the internal scar and results in repeat adhesions [5]. To minimize needle-induced adhesiolysis, we used the thinnest needle (30-gauge needle). Injection of hyaluronidase into the fibrotic scar lesion was effective in improving the pliability, height, and pigmentation of the fibrotic lesions by breaking down the ground substance of the connective tissue [1].

The VSS is used primarily as an index of scar after external wound. In the absence of appropriate indicators for the judgment of hematoma or swelling, we compared the efficacy of hematoma and swelling using the VSS in this study. The VSS is evaluated on four scales: pigmentation, vascularity, pliability, and height. In hematoma, pigmentation, pliability, and height can be applied. In fibrosis, all four scales are improved in the treatment response, so we decided that it is appropriate to judge the treatment response. In mild hematoma and fibrosis cases, hyaluronidase injection may be considered as an alternative to hematoma removal treatment by surgical methods.