Clinical treatment of nevus of Ota

Nevus of Ota is also known as brown-green nevus on the palate and melanocytosis in the dermis of the eye. It was first reported by Dr. Ohta in 1938, hence the name "Nevus of Ota". Nevus of Ota is a gray-blue patchy lesion that affects the sclera and the ipsilateral face along the ophthalmic and maxillary branches of the trigeminal nerve. It is more common in people of color, such as Orientals and black people. More common in women. The age of onset has two peak periods in infancy and adolescence, with the incidence rate within 1 year old accounting for 61.35%.

1. Causes and pathogenesis

Nevus of Ota may be related to genetics. It is an autosomal dominant inheritance. It means that during embryonic development, when melanocytes migrate from the neural crest to the epidermis, they fail to pass through the junction of the epidermis and the dermis for some reason and stay in the dermis. lesions. Some studies believe that it may not be the remnants of melanocytes, but a hamartoma or nevus-like lesion similar to blue nevus.

2. Clinical manifestations

Ota nevus mostly occurs on one side of the face, and 5% to 10% of patients develop it on both sides of the face. The damage is usually distributed in the parts innervated by the first and second branches of the trigeminal nerve, that is, the upper and lower eyelids, periorbital area, zygomatic area, temporal area, Forehead and nose. About 2/3 of the patients have blue staining of the ipsilateral sclera, and a few patients may also have involvement of the palate and buccal mucosa. The skin lesions are usually patchy, with occasional nodules, and can be brown, blue-gray, blue, black and other colors. The patches are unevenly colored, in the form of spots or reticulates, and the boundaries are unclear. Generally, brown pigmentation is mostly reticular or map-shaped, while blue pigmentation is more diffuse, and the color of the spots often deepens with age.
50% of pigment spots are congenital, and the rest appear after the age of 10, and occasionally appear late or during pregnancy. A few patients may be accompanied by Ito nevus, persistent Mongolian spots or port wine stains. Nevus of Ota rarely become malignant.

3. Pathological characteristics

Melanocytes are generally located in the middle layer of the dermis and can involve the upper dermis or subcutaneous tissue. The number of melanocytes is larger, more at the bulge of the lesion, and the cell body is elongated, spindle-shaped, and scattered among the dermal collagen fibers. Melanophages can be seen in a few lesions. If the lesions involve the eyes, in addition to the skin tissue, melanocyte infiltration can also be seen in other tissues including the deep periosteum.

4. Diagnosis and differential diagnosis

The diagnosis can be made based on the pigment's color, distribution, and eye involvement. It needs to be distinguished from Mongolian spots and blue nevus.
(1) Mongolian spots are present at birth and can disappear naturally. It does not affect the eyes and mucous membranes. Black in tissue and dermis
The number of cells is smaller and the location is deeper.
(2) Blue nevus is a blue-black papule or small nodule, which commonly occurs on the back of the hands, feet, face, and buttocks. It contains melanin in the tissue.
Cells clump together.

5. Treatment

Pigment abnormalities in nevus of Ota persist throughout life, and the pigmentation increases with age, especially after puberty. Nevus of Ota is a hypermelanosis of the dermis. Therefore, traditional chemical peels, peeling, skin grafting, freezing, continuous laser and other treatment methods that damage the epidermis to the dermis are not only difficult to completely remove melanocytes in the dermis, but also cause epidermal skin damage. and irreversible damage to surrounding normal tissues, such as scars, persistent pigment abnormalities and other adverse reactions. Nowadays, the application of modulated laser can not only completely cure nevus of Ohta, but also cause no trauma to the epidermal tissue.
O-switch laser can effectively penetrate the epidermis and reach the pigment groups deep in the dermis. Using the blasting effect of the laser, the melanin instantly expands and ruptures to form tiny fragments after absorbing the strong-energy laser. In the subsequent inflammatory reaction, , the pigment particles are engulfed by macrophages and degraded by acid hydrolase or metabolized through the lymphatic system.
The pulse time of the zero-adjusted laser is shorter than the thermal relaxation time of the skin, and no thermal dispersion occurs. The heat generated by the laser has no time to be transmitted to the surrounding normal tissues and epidermis. While the pigment particles are removed, the normal tissue structure and cell framework remain intact and intact. It repairs quickly, so no scars will be produced even after multiple treatments, and good therapeutic effects can be achieved.
(1) Q-switched ruby laser
The wavelength is 694nm, the pulse width is 20~40ns, and the peak power is above 10mW. It has good absorption of melanin and strong penetrating power, and can be used to treat various endogenous or exogenous pigment diseases. Moreover, the absorption of hemoglobin at this wavelength is significantly reduced, forming a trough, so the risk of causing purpura or bleeding is relatively lower than other lasers. However, it is also significantly absorbed by epidermal melanin, thereby increasing the risk of hypopigmentation in darker skin. It was used earlier in Q-switched laser treatment for nevus of Ota. Laser treatment operation steps:
1. Precautions before surgery
(1) It is recommended not to apply foundation cosmetics within 1 week before surgery.
(2) Pay attention to sun protection before treatment to prevent the appearance of sun spots. If sun spots have already appeared, you need to treat the sun spots first and wait until they subside before performing laser treatment.
(3) If the facial skin itself has inflammation, treatment should be given to control the facial inflammation first.
2. Preoperative Cleansing Before facial treatment, the skin must be cleansed first. The treatment area is commonly used to disinfect the skin with chlormethionine, and treatment can be performed after the skin is dry. Do not use iodophor to disinfect the skin because it can cause irritating dermatitis, is difficult to clean after external use, and may affect laser absorption.
3. Topical anesthesia/general anesthesia does not require anesthesia if the skin lesions are small and the pain can be tolerated. Compound lidocaine ointment can also be used on the treatment area for about 60 minutes before laser treatment, which can reduce the pain by about 50%. . If the skin lesions are large, sensitive to pain, or the patient is young and may not cooperate during treatment, treatment under anesthesia may be considered. Local infiltration anesthesia or block anesthesia can be used for small-area skin lesions in children or adults, and general anesthesia can be used for large-area skin lesions in children.
For large-scale nevus of Ota on one side of the face, the following nerve block anesthesia can be used:

① infraorbital nerve;

② zygomatic nerve;

③ Supratrochlear nerve;

④ Supraorbital nerve. Infiltration anesthesia is recommended for the mid-lateral cheek and upper eyelid areas. When performing laser irradiation around the eyelids, a metal corneal protective shield needs to be worn after instilling topical anesthetic into the eye to prevent laser damage to the cornea. For local infiltration anesthesia, use a 27-gauge needle and inject 1% lidocaine containing epinephrine as slowly as possible. Each injection point should be at the site where the previous injection of infiltration anesthesia has taken effect to reduce pain. 4. For eye protection, the operator should wear special goggles. When giving local anesthesia around the eyes, be careful not to insert the needle too deep and injure the eyeball. The patient can first wear a corneal protective shield or corneal protective plate before anesthesia is performed
injection. 5. Intraoperative treatment response: The diameter of the spot treated is 3~7nm, and the reference energy density is 4~8J/cm?. It is better to have immediate skin whitening at the irradiated site. Mild edema and congestion may occur after the skin turns gray, but this is not necessary. Blisters should form. It is better to lower the energy density of darker parts by 0.5~1J/cm? The laser is irradiated to the point where the skin is just white, and there is a slight time interval between the next emission spot. The laser is irradiated one spot after another, and there should be an overlap of 20% to 40% between the spots. Usually more than 5 times.
6. Postoperative treatment of the surgical area. There will be obvious swelling of the skin after treatment. Immediately apply ice for 20 minutes, and then use Vaseline ointment and non-stick gauze for external application to maintain a local moist environment for 7 to 10 days. The following reactions may occur in the surgical area after laser treatment:
(1) Blisters: Mainly occur in darker skin lesions or when the treatment dose is high. Once blisters appear, you should actively prevent infection and wait for more than 1 to 2 weeks to dry up.
(2) Hypopigmentation: It is more common after ruby laser treatment. Most of it is temporary and basically disappears in about 6 months.

17. Precautions after surgery
(1) The new skin after laser treatment of skin lesions and scabs is delicate, so gentle and non-friction stimulation methods should be used to wash your face and put on makeup.
(2) During the interval between two treatments, you need to use sunscreen to prevent sun exposure.
(3) Inflammatory pigmentation will last longer after laser treatment and generally lasts for 3 to 4 months before it subsides. The next treatment must wait until the lightening of pigmentation after the last laser has subsided. If re-treatment is performed when the pigmentation has not subsided, the laser will be absorbed by the melanin in the epidermis and will not reach the dermis, affecting the treatment effect and prolonging the pigmentation time.
(4) Patients receiving Q-switched laser treatment once can only destroy some dermal melanocytes. Therefore, the pigment of most cases does not change significantly after the first treatment. After 2 to 3 treatments, the pigment of most cases begins to lighten and the effect is obvious. It is more common after 3 treatments, and the treatment effect will be more obvious as the number of treatments increases. The treatment cycle is usually 5 to 6 months. If the interval is too short, the treatment effect will be affected. Because the melanin particles that are crushed in the skin lesions after treatment cannot be removed immediately, it takes a period of time to be metabolized by the body's defense system.
(2) Alexandrite Q755 laser
Wavelength 755nm, pulse width 50~100ns. The light spot for treatment is 2~6mm, and the reference energy density is 6~10J/cm2. The treatment is also suitable when the treatment area becomes gray and white. After a few minutes, a small amount of blood will ooze out and turn dark red. Generally, there will be no spot-like bleeding.  This wavelength has a better absorption effect on brown pigment. Therefore, the Q755 laser can be used for treatment of Ota nevus with light-colored, tan-colored lesions and shallow lesions. It is more suitable for nevus of Ota in infants, children, around the eyes, and those with delicate skin. treat. (Pre-treatment operations and post-treatment care are coordinated with the Q694nm laser.)
(3) Q switch Nd: YAG laser Im
The wavelength is 1064mm, the pulse width is 4~10ns, the light spot is 2~6mm, and the energy density is 5~9J/em’. This laser has the characteristics of longer wavelength, short pulse width, and deep penetration. Brown pigment has poor absorption of 1064nm wavelength laser, while melanin has good absorption. Therefore, it is the best choice for skin lesions with dark blue or blue-black nevus of Ota. Q-switched Nd:YAG1064m laser works best. Immediately after treatment, the skin lesions turn white, and then large needle-like spots of blood ooze out, forming blood scabs to cover the wound surface. The scabs will fall off and heal after 7 to 10 days or more. In some patients, it may take 2 to 3 weeks for the skin to fall off. Purple lesions may occur in areas with relatively thin and tender skin tissue and rich blood vessels, such as eyelids and temporal regions, which usually subside in about 1 week and do not require special treatment. The pre-treatment operation and post-treatment care are coordinated with the Q694nm laser.
1. Prognosis Q-switched laser is used to treat nevus of Ohta clinically. Generally speaking, the younger the patient, the better the effect and the fewer times of treatment. This is because young children’s skin is thin, the skin lesions are superficial, and their metabolism is stronger. Children generally need 2 to 3 times, and adults generally need 5 to 6 times.
For skin lesions, the treatment effect is generally the best for skin lesions in prominent areas such as the forehead and zygomatic area, while the treatment effect for skin lesions on the eyelids is relatively poor, which may be due to the loose tissue of the eyelids, scattered pigment cells and high tissue moisture content. In addition, lighter-skinned patients have better treatment outcomes and require fewer treatments than darker-skinned patients. Because the melanin in the skin of people with darker skin absorbs more laser energy, it weakens the laser intensity that penetrates into the deep tissue of the skin, thereby weakening the effectiveness of the laser.
2. Recurrence: If the skin lesions are not completely cleared, there is a probability of recurrence or re-exacerbation of pigmentation after treatment is interrupted. The triggers for its recurrence may be related to sun exposure, fatigue, and fluctuations in estrogen levels during menstruation, pregnancy, and adolescence. When the skin color is close to normal or has become normal when observed with the naked eye, if abnormal pigment cells of nevus of Ota still remain in the dermal tissue, it will appear later. Sun exposure, fatigue, or stimulation by sex hormones may activate melanocytes in the dermis, resulting in the reappearance or aggravation of pigmented spots. Therefore, early treatment is recommended for treatment. Female patients before childbearing age should try to treat the skin lesions thoroughly. After treatment, avoid excessive sun exposure. Long-term follow-up should be carried out. If recurrence occurs, timely and active treatment should be carried out.

Source: Clinical treatment of nevus of Ota