Brief introduction.
Since the skin expander was applied to clinical practice, skin expansion has been widely used as an effective treatment tool in various fields of plastic surgery, such as for breast, external ear and nose reconstruction, treatment of post-burn and burn scars, etc. From the patients with nevus nigricans we have treated, skin expansion is undoubtedly also the most commonly used treatment tool for congenital nevus nigricans; whether for medium-sized nevus Whether for medium-sized nevi, large nevi or giant nevi, as long as the patient is properly selected and the surgical design is reasonable, treatment by skin dilation can generally achieve relatively good treatment results.
With the increasing application of skin dilation in clinical work, many parents of children with congenital nevus have also learned about skin dilation through various channels, and they hope that their children can also be treated with skin dilation, but the application of skin dilation presupposes that there is enough normal skin around the nevus lesion, otherwise, reluctant use of skin Otherwise, it is not possible to obtain a good treatment result.
In addition, skin dilatation has certain requirements on the age of the child, and usually the child can cooperate well with skin dilatation treatment when he or she is about 5 weeks old; some parents of the child are eager to seek medical treatment and always want to treat the child earlier, so if the operation is performed too early, the child cannot cooperate well, which may cause difficulties in dilator injection and may lead to leakage of the dilator injection pot, which is not worth the loss.
For congenital nevus of different parts of the body, when applying skin dilatation for treatment, because the skin of different parts of the human body differs in skin thickness, texture, color and degree of tolerance to skin dilatation, the treatment techniques are also different. Below, some characteristics of nevus of different parts of the human body when applying skin dilatation for treatment are described in order.
I. Scalp nevus
Scalp nevus is one of the most prevalent parts of congenital nevus. Generally, the nevus on the scalp will be integrated with the nevus on the face, neck and neck, and the parents of the child will choose to treat the nevus on the exposed part; if the area of the scalp nevus is within 50% of the total area of the scalp, the treatment by skin dilation can often achieve good treatment effect.
The scalp is thick, rich in blood flow and supported by the skull, therefore, skin expansion is highly efficient. Choosing the appropriate size and shape of dilator according to the size and shape of the lesion, and designing the expanded scalp appropriately after the expansion process is completed are the keys to ensure the success of the procedure.
Typical case 1
This is a patient with a giant nevus on the scalp and dorsal side of the neck and shoulder. The size of the nevus in the scalp was about 25×250px, and a rectangular 600ml expander was buried in the normal scalp above the scalp lesion, and after 3 months of expansion, the expander was removed and all the nevi in the scalp above the hairline were excised, and the expanded scalp flap was used to advance the transfer to repair the wound. (Figure 1).
Figure 1. (Right) Preoperative image showing nevus nigricans on the scalp and neck. (Middle) The scalp expander is filled with water. (Right) Postoperative image, showing the effect of scalp repair and the direction of hair distribution.
II. Face and neck nevi
Because of the exposed location and many aesthetic organs in the face and neck, nevi in these areas have the greatest impact on the patient’s appearance and can also have a significant impact on the child’s psychological development, and are more difficult to treat.
In order to obtain the best treatment effect in the face and neck, it is necessary to follow the principle of aesthetic subunit reconstruction as much as possible. When designing the location of skin incisions, one should try to hide the final incision scar within the natural folds of the skin, such as the nasolabial folds; one should also pay attention to not exerting excessive pulling force on some important aesthetic structures, such as eyebrows, eyelids and mouth, so as not to cause pulling deformation of tissue structures.
Typical case 2
This is a case of congenital nevus nigricans in the cheek, the size of the nevus is about 6×125px, the nevus is close to the corner of the mouth and nose and has been distributed to the upper lip, which is difficult to treat; because there is a relatively large area of normal skin tissue of the cheek on the outside of the nevus, we choose to apply buccal skin expansion for treatment. In the 1st operation, a dilator was buried in the buccal area and injected with water for 3 months; after the dilator was fully expanded, the facial nevus was completely excised, the dilator was removed, and the dilated flap of the buccal area was rotated and advanced to the defective area to repair the wound; in order to make full use of the expanded skin, some additional incisions needed to be made on the normal skin; although these additional incisions made prolonged incisional scar, in order to maximize the use of the expanded out In order to make full use of the expanded skin, these additional incisions are sometimes unavoidable, and we hope that the patients and their families can understand this (Figure 2).
Figure 2. (Right) shows a facial nevus. (Middle) The buccal dilator is completed. (left) Post-operative image
Typical case 3
This is a patient with a congenital preauricular and external ear nevus. The nevus is characterized by a lesion located in the preauricular area and invading the earlobe; although skin grafting is also a good option, the dark color of the skin piece after surgery is its deficiency. Since there was available normal skin in the postauricular mastoid area, we placed an expander in the normal skin behind the ear during the first surgery. After the expansion, all the nevus was excised, and the expanded flap behind the ear was rotated and advanced for transfer to repair the anterior skin defect and reconstruct the earlobe at the same time (Figure 3).
Figure 3. (Right) Preoperative image showing the preauricular nevus. (Middle) Completion of dilatation by dilator. (Right) Postoperative image
III. Trunk nevus
The posterior trunk is the most common site of appearance for giant nevi, which usually follow the direction of distribution of the dermatomes and extend anteriorly.
If the nevus is confined to the lower or central abdomen, treatment of the nevus with skin dilatation around the lesion is a very limited treatment because there is sufficient normal skin above the lesion or above and below the nevus; however, it must be noted that in female patients, dilatation treatment in and around the center of breast growth must be avoided so as not to interfere with breast growth and development.
For nevi on the upper back and neck, or on the back, buttocks, and perineum, it was previously thought that nevi in these areas could only be treated with skin implants; however, with the increasing maturity of skin expansion techniques, nevi in these areas can also be treated with skin expansion, especially the continuous expansion technique, which I will introduce in detail at the end of this article.
IV. Treatment of nevus of the extremities
The traditional view is that the application of tissue expansion for the treatment of nevus of the extremities has a high complication rate and limited value.
The shape of the extremities as well as the elasticity and flexibility of the skin and other characteristics determine the difficulty in applying skin expansion techniques. If the lesions are distributed along the circumferential direction of the extremities, the application of skin expansion can be considered for patients with more available normal skin; on the contrary, if the lesions are arranged along the long axis (or longitudinal axis) of the extremities, the application of skin expansion for the treatment is more difficult to obtain the ideal treatment effect is more difficult.
We have accumulated some experience in treating patients with nevus of the upper extremities. For large-area annular nevus of the upper extremities, we have used a combination of pre-expanded tipped flaps, such as expanded scapular flap, latissimus dorsi muscle flap and paramedian flap, and have obtained very good treatment results.
For large nevi of the lower extremities, there is no suitable local tipped flap available, and a combination of local tipped flaps, free flaps and implants must be used to obtain better treatment results.
V. Continuous expansion technique for giant nevus
Since the skin expansion technique was proposed for more than 30 years, scholars have designed many ingenious skin expansion methods, among which continuous expansion technique is a very effective skin expansion method, which is also widely used in clinical work for the treatment of congenital pigmented nevus, especially giant nevus.
Below we illustrate this technique specifically in a patient with a giant nevus on the back, left side of the waist and chest.
The figure shows that the nevus is located on the back, than extends to the left side of the waist and chest, the area of the nevus is large, however, there is still a relatively large area of normal skin above, below and to the side of the nevus, therefore, we decided to treat this patient with the continuous expansion technique, in the 1st operation, we buried 2 dilators in the normal skin of the right shoulder, dorsal side and chest, after the wound healed well, we performed After the dilator is filled with water, we remove the dilator, remove a part of the nevus lesion, push the dilated flap to the lesion site and transfer it to repair the defect formed after the nevus is removed; at this time, we bury the dilator under the dilated flap again, wait for the wound to heal, and continue the skin expansion treatment, and so on and so forth until the whole nevus lesion is completely removed.
The application of the continuous skin expansion technique presupposes that there is enough normal skin around the nevus to be used. The advantage is that it can maximize the use of normal skin, shorten the treatment time, reduce the number of operations, and also reduce the number of anesthesia that the patient has to go through.
For the treatment of giant nevi, the continuous dilation technique is a very effective treatment method.