Treatment of a Congenital Melocytic Giant Naevi at Age 39 Using Split-Thickness Skin Graft Over an Artificial Dermal Scaffold Through 2-Step Operation: A Novel Technique and Literature Review

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Congenital melanocytic nevi (CMN) are dark-colored lesions that are benign proliferations of melanocytes present at birth or developing within a few months after birth, and they can cover large areas.¹ The prevalence of CMN in newborns has been reported to range from 0.5% to 31.7%.² Giant CMN (GCMN) is defined as CMN with a diameter of 20 cm or more in adults and 6 cm on the body and 9 cm on the head in newborns.²

In the past, the risk of developing melanoma was estimated to be as high as 42%, leading to treatment strategies focused on preventing malignancy.¹ However, currently the malignancy risk for CMN is estimated at 2.0%, 2.5% for LCMN (large CMN), and 3.1% for GCMN. As a result, in the last decade, treatment indications have shifted from preventing malignant transformation to improving appearance and psychosocial well-being.¹

It has been reported that the malignant transformation of GCMNs often occurs during prepubescence or childhood.² Due to the psychosocial impact of the lesion on children and their families,³ as well as the greater skin flexibility in childhood,⁴ early treatment at the earliest possible age is recommended. However, there is currently no consensus on the best approach to treating nevi.¹

The treatment of GCMNs is influenced by various factors, such as size and localization. There are several treatment options available, including direct closure, serial excision, local flaps, skin grafts, and skin expansions.⁴ In recent years, the use of dermal skeletons and cultured epidermal autografts (CEA) has also been introduced.²

In this case presentation, the successful treatment of a 39-year-old patient with GCMN located on the back is presented using a 2-step operation involving fascial excision, dermal scaffold placement, and split-thickness skin grafting.

A 39-year-old male patient presented to our clinic with a GCMN covering his entire back (approximately 10% of the total body surface area [TBSA], estimated using a Lund-Browder chart) and a large lipoma-like mass on the left posterior flank region, causing physical discomfort to the patient (Figure 1). No previous interventions, including biopsy, had been performed on the lesion. After deciding to proceed with a 2-step operation, written informed consent was obtained from the patient.

Figure 1. Preoperative giant congenital melanocytic nevi on back and wrist.

In the first session, the entire lesion was excised en-bloc with fascial excision in a prone position under general anesthesia (Figure 2). Double-layer Pelnac was applied over the fascia and secured to the healthy skin with staples. ActiCoat was placed over the Pelnac as a dressing (Figure 2). On the 13th day postoperatively, the Pelnac dressings were removed, revealing a granulated wound bed. A 1:3 mesh split-thickness skin graft was applied to cover the entire area (Figure 3). During follow-up, approximately 10% of the graft lysed. On the 18th day after the first graft application, a second split-thickness skin graft was performed on the areas with lysis, and this time, 100% graft take was achieved (Figure 4).

Figure 2. (A) The excised specimen. (B) Wound bed after excision, (C) application of Pelnac, and (D) secondary dressing with Acticoat.

Figure 3. After Pelnac removal, application of split-thickness skin graft.

Figure 4. Second grafting.

Follow-up images at 56 days, 6 months, and 1 year post-excision are shown in Figure 5. Long-term follow-up revealed the development of hypertrophic scars in the areas where the second graft was applied. These hypertrophic scar areas received 2 intralesional triamcinolone injections at a 3-week interval. Post-injection images are also shown in Figure 5.

Figure 5. Postoperative first year.

Histopathological examination of the excised GCMN did not reveal any malignancy.

The case presented in this study is the first instance in the literature of a GCMN excision performed on a 39-year-old patient. In this case, the GCMN covering 10% of the TBSA was excised in a single session, and simultaneously, a dermal scaffold (Pelnac, Gunze Ltd) was applied to the area, followed by closure of the defect with split-thickness skin graft.

GCMNs are lesions that are present at birth and can reach a diameter of 20 cm or more in adulthood, occurring on any anatomical region of the body.⁵ Some authors define GCMNs as lesions too large to be resected in a single operation or those exceeding 100 cm in diameter.⁵ The incidence of CMNs in newborns has been reported to be between 0.2% and 2.1%, with a higher prevalence in females (male-to-female ratios ranging from 1:1.17 to 1:1.4).⁵

The most common complication seen in CMNs is the development of malignancy. Currently, the risk of malignancy varies depending on the size of the lesion and ranges from 2.0% to 3.1%. Due to the risk of malignancy development, it is preferred to treat CMNs during childhood.²

In a review and meta-analysis conducted by Gout and colleagues in 2023, various surgical approaches for the treatment of CMNs were evaluated.¹ The summary of the studies included in this review and subsequent studies published after this review is presented in Table 1. The literature search revealed that the majority of CMNs and GCMNs were treated during childhood. The oldest patient to undergo intervention was 36 years old, with a CMN located on the cheek.¹ The meta-analysis showed that there were no cases of total excision of GCMNs in a single session.

Table 1. Literature Review: Patients and Treatment Modalities

The use of artificial dermal scaffolds with split-thickness skin grafts was first reported in the years 2010 and 2011. Subsequently, in 2021, a 6-year-old male patient underwent serial excision and Integra application, followed by STSG to cover the area.⁵ After this case presentation, in 2022 a study presented 14 cases in which 8 GCMN cases underwent excision, Pelnac application, and then closure of the defect with STSG.⁶ A total of 23 patients were identified in the literature where the GCMN defect was closed using a dermal scaffold (Table 2). The patients' ages ranged from 0 to 15 years. The excised CMN sizes varied between 1% to 12% of the TBSA, with 13 patients having lesions located on the back and buttock.

Table 2. Patients in Whom Dermal Scaffolds Were Used for Defect Closure Followıng Giant Congenital Melanocytic Nevi Excision

With this case, the removal of such a large nevus located on the waist and back in an adult, which has not been previously discussed in the literature, has brought some other benefits into consideration. A neuroaxial block is not an ideal technique for patients having an overlying back mass since there is technical difficulty due to obliteration of bony landmarks by the overlying mass. Additionally, inserting a needle through a mass has a risk of seeding the epidural space with cells of the mass. There may also be a risk of bleeding. In the literature there is only 1 case report of epidural catheter placement through an overlying lower back lipoma for vascular bypass surgery of the lower extremity.¹² However, a neuroaxial block can be easily applied after tissue integrity is ensured. In addition, the availability of this area for possible vertebral surgeries will facilitate the procedures that the patient may undergo.

For this case, Pelnac was preferred due to its 3-mm thickness and double-layer scaffold structure, exhibiting a more pliable characteristic based on our clinical experience. During the follow-up period, the patient did not experience any complications, and in the first STSG session, a 90% graft take was achieved. A second STSG was applied to the 10% of the area with graft lysis, resulting in 100% graft take, successfully closing the entire defect.

In the 1-year follow-up images of the patient, the skin's pliability is adequate (Figure 6 and Videos 1 and 2). After the removal of the fat tissue in the left flank, the patient has mentioned that they no longer experience any discomfort while sitting or lying down. Cosmetically, the patient has expressed that the current scars do not bother them compared to the previous condition with the large and hairy giant nevus.

Figure 6. Postoperative 16th month; pliability of the skin even at hypertrophic scars.

Videos 1 and 2: Postoperative 16th month; pliability and elasticity of the skin let the patient move easily.

Studies using dermal scaffolds have reported the disadvantages of prolonged treatment duration and infection risk.² However, in the case presented in this study, the excision of the entire pathological skin structure and complete re-epithelization took a total of 35 days, and there were no infections during the perioperative period and afterwards.

In this report, we aimed to share our treatment experience with a patient who underwent a 1-stage excision of a 39-year-old GCMN covering 10% of TBSA along with the removal of distrophic fat deposits, followed by double-layer Pelnac application and subsequent grafting.

The goal was to demonstrate that GCMNs, which are often treated surgically before puberty due to the risk of malignancy and psychological problems, can also be successfully treated without complications in advanced age, as shown in this case. The application of split-thickness skin graft on the dermal scaffold proved to be a safe and effective method, resulting in rapid healing with a pliable skin texture.

The outcomes of this case may be considered as an alternative approach in the treatment of GCMNs, providing valuable insights for clinical practice.