Use of Autologous Cultured Epidermis to treat severe birthmarks (giant congenital melanocytic nevus) has been covered by insurance since December 1, 2016.
What is a giant congenital melanocytic nevus?
Nevi are dark-brown marks that range in size from small mole-like dots to giant patches. They form when melanocytes (cells with brown pigment) accumulate within the structure of the skin, either between the dermis and epidermis or within the dermis itself. Among these, giant congenital melanocytic nevi (GCMN) are those that are present from birth, and they may appear on the trunk of the body, the hands and feet, or on the head, etc. By definition, a GCMN is a birthmark with a diameter of at least 20 cm in an adult or 6 cm on the trunk or 9 cm on the head of a small child. A GCMN does not go away as the child matures, and there is a risk of it developing into malignant melanoma (skin cancer) in the future (occurs in about 3% of cases in Japan). Half of such cases of malignant melanoma have their onset by the time the child is 3 years old, so early removal of the affected part is desirable.
Treatment method
There are a number of different methods for treating GCMNs, and some combination of the following may be used.
Method using Autologous Cultured Epidermis (epidermal cell sheet)
Part of the patient's own healthy skin is cut away and cultured in a special facility to produce an epidermal cell sheet. After the birthmark is removed, this epidermal cell sheet is used to cover the resulting open wound, and in a few weeks or months' time, the engrafted sheet closes the wound. The epidermal cell sheet is a technology that was developed in the United States in 1975, and it has been covered by Japan's National Health Insurance for use in treating extensive burns since 2009.
Nevus removal methods using Autologous Cultured Epidermis
Laser therapy
This consists of several rounds of treatment in which laser beams from a ruby laser, Q-switched ruby laser, or Q-switched Alexandrite laser, etc., are applied to the skin. However, it is considered difficult to completely remove the coloration since nevus cells (melanocytes that cause the birthmark) still remain within the skin even after application of the laser.
Surgical excision and reefing
The birthmark is cut away, leaving a spindle-shaped surgical wound that is sewn together.
Partial removal
If the birthmark is large, it may be removed in 2 or 3 stages, a little at a time, with the surgical margins sewn together.
Skin graft
If the birthmark is even larger and cannot be treated with partial removal, the surgical wound is covered by grafting on unblemished skin removed from its periphery (local skin slap).
Method using dermatome or curettage
This method involves removing the surface layer of the birthmark and waiting for the wound to heal.
Method using expander
In this method, the skin is expanded by implanting a silicone sac under the skin around the birthmark. Then, when the birthmark is cut away, the expanded unblemished skin around the periphery is used to cover the wound.
The use and commercialization of the medicinal products developed by Japan Tissue Engineering Co., Ltd. that are referred to on this website are approved only in Japan. A potential use and commercialization in other regions will be subject to the prior granting of a marketing authorization in the given territory and compliance with applicable laws.