Serial excision with power-stretching of the skin in giant melanocytic nevi therapy

Serial tissue expansion and excision for reconstruction of giant dorsal congenital melanocytic nevus: A case report

Giant congenital melanocytic nevus often necessitates meticulous planning and multiple treatment stages for complete surgical excision. This report presents a case of giant congenital melanocytic nevus on the back managed through serial tissue expansion and excision. Initially, two expanders were placed at the deep fascia level. Sequential outpatient expansions over 10 weeks were followed by expander removal, partial nevus excision, defect coverage with expanded skin flaps, and simultaneous placement of a new expander. The subsequent single expander expansion over 12 weeks involved a total of 600 mL of saline. After three operations spanning approximately 6 months, 54 cm × 36 cm of giant congenital melanocytic nevus skin, covering 65% of the patient's back, was completely excised. Serial tissue expansion and excision may be an effective surgical approach for managing dorsal giant congenital melanocytic nevus, reducing the need for multiple surgeries and achieving favorable aesthetic outcomes.

Updates in the Management of Congenital Melanocytic Nevi

Congenital melanocytic nevi (CMN) carry an increased risk of melanoma and may be disfiguring, and consensus regarding treatment recommendations is lacking. While clinical monitoring is the standard of care, many caregivers are interested in its removal to prevent psychosocial burden or to decrease risk. Although melanoma can occur regardless of CMN removal, there are a variety of treatments that may offer improved cosmesis or local symptom control, including surgical excision, laser therapy, and other superficially destructive techniques. Regardless of the selected management, these patients are monitored for ongoing melanoma risk. An extensive discussion with families regarding the risks and benefits of observation versus active intervention is essential. To facilitate these discussions, we herein summarize current CMN management strategies and considerations.

Serial excision surgery for giant dorsal congenital melanocytic nevus: Case report

INTRODUCTION AND IMPORTANCE

Giant congenital melanocytic nevus increases the risk of melanoma and seriously affects the aesthetics and psychology of patients, influencing the personality development of children.

CASE PRESENTATION

A 7-year-old female child presented with a giant congenital melanocytic nevus on the back, which extended from the right anterior abdominal wall to the left flank Taking advantage of the elasticity of children's skin, we performed serial excision and obtained favourable results. The procedure included seven surgeries, and the average interval between the surgeries was 7 months. The nevus was partially resected from the periphery to the centre, and the direction of excision of the nevus depended on the mobilisation of the surrounding normal skin, including from the shoulder downward, lateral to medial, and from the bottom upward. After the seventh surgery at 11 years of age, the nevus was completely removed, and there were no complications.

CLINICAL DISCUSSION

Serial excision is a simple and less invasive surgical technique that can achieve both complete excision and a satisfactory aesthetic result for giant congenital melanocytic nevus. The giant nevus of the back can be removed completely after several procedures due to the very good elasticity of the skin and the great ability of natural expansion of healthy skin under a considerable stretching force in children.

CONCLUSION

Serial excision is an effective method for treating dorsal giant congenital melanocytic nevus in children because of excellent natural skin elasticity.

Tumescent local anaesthesia for the surgical therapy of congenital nevi in the first year of life

BACKGROUND

The indication for surgical treatment of congenital nevi must be made after individual consideration of the expected benefit and risk and requires careful information of the parents as well as interdisciplinary psychological support. In addition to suspected malignancy, a relevant indication is the risk of stigmatization depending on the size and localization of the nevus. Objective was to show which size reduction of the congenital nevus can be achieved by surgical therapy under tumescent local anaesthesia (TLA) in infancy and how often complications of anaesthesia or surgery occur.

METHODS

All infants up to 12 months of age who underwent surgery for a congenital nevus under TLA at the University Dermatological Clinic Tuebingen between January 2015 and December 2021 were included; surgeries were performed using serial excisions (powerstretching technique), whereby the incisions were made inside the nevus and mobilization was strictly limited to the skin side without nevus.

RESULTS

Overall, a cumulative total area of 38.65 cm² could be removed on average within the first year of life (trunk: 67 cm² , head: 21.2 cm² , legs: 21.6 cm² , arms: 13.2 cm² ). A cumulative maximum area reduction of 406.9 cm² could be achieved. We evaluated 363 surgical sites (123 children) on all body regions. The median age of the children at the first surgery was 3.5 months (0.46-10.7 months). Complications occurred in 2.3% (seven procedures). All these complications were reversible in the course of the operation and did not lead to a prolonged hospital stay. No anaesthesia-related complications occurred.

CONCLUSION

We were able to show that a reduction of large areas of congenital nevi is possible in the first year of life with the combination of serial excisions using powerstretching technique, TLA, and intracutaneous butterfly sutures.

Establishment and characterization of an immortalized human giant congenital melanocytic nevi cell line

Treatments for giant congenital melanocytic nevi (GCMN) are extremely limited. Thus, there is an urgent need for development of relevant targeted therapies. However, current lack of preclinical cell models restricts progress in GCMN research. In this study, we aimed to establish and characterize an immortalized GCMN cell line. GCMN cells were successfully immortalized by means of lentivirus-mediated simian virus 40 large T transfection. The immortalized GNC cell line (ImGNC) showed lower proliferation rate and higher melanin content than primary melanocytes. Expression levels of the differentiation gene MITF and stemness genes TWIST1, SNAI1, and FOXD3 were elevated in ImGNCs; however, the established ImGNC cell line was immortalized but not transformed. Sanger sequencing detected the heterozygous NRAS^Q61K mutation in ImGNCs, but not the BRAF^V600E mutation. Despite carrying the NRAS^Q61K allele, ImGNCs demonstrated suppressed MAPK activation and elevated PI3K/Akt activation, as compared with primary melanocytes. Drug sensitivity analysis showed that ImGNCs are more sensitive to PI3K/Akt and Bcl-2 inhibitors than to MEK or ERK inhibitors. Unlike the proliferation-inhibiting effect of PI3K/Akt inhibitors, the Bcl-2 inhibitor navitoclax promptly promoted apoptosis in ImGNCs. Considering the low proliferation characteristics of GCMN in vivo, Bcl-2 may be a potential therapeutic target that warrants further research.

Histological and Immunohistochemical Changes of Congenital Melanocytic Nevi With Age

ABSTRACT

Clinical but not histological changes of congenital melanocytic nevi (CMN) with age are well characterized. Our objective was to analyze histological changes of CMN with age and discuss possible clinical implications of our findings. We investigated serial excisions of 21 patients with CMN and compared histological and immunohistochemical features over time. The median number of serial excisions was 6 [interquartile range (IQR) 5-7], the median age at the first excision was 12 months (IQR 5-98), and the median time between the first and last analyzed excision was 53 months (IQR 45-64). The projected adult size of the excised CMN was "large" or "giant" in 14 of the 21 CMN (67%) and "medium" in the remaining lesions (33%). Nineteen CMN (90%) involved the subcutaneous fat, and 16 of the 21 CMN (76%) reached the lower surgical margin. The histological pattern and depth did not change over time but the cellularity and HMB-45 expression of dermal melanocytes decreased in 16 of the 21 patients (76%) and in 15 of the 21 patients (71%), respectively (both P < 0.001). Patients with decreasing HMB-45 expression were significantly younger at the first excision (median 6 months, IQR 4-28) than patients with unchanged HMB-45 expression (median 176 months, IQR 12-186; P = 0.018). The expression of Ki-67 and p16 did not change significantly with age. Our study demonstrates that (1) the cellularity and pigment production of CMN decreases with age, (2) the histological pattern and extension in depth remain stable, and (3) clear resection margins can rarely be achieved in larger CMN.

Neurocutaneous melanocytosis (melanosis)

Neurocutaneous melanosis (NCM; MIM # 249400; ORPHA: 2481], first reported by the Bohemian pathologist Rokitansky in 1861, and now more precisely defined as neurocutaneous melanocytosis, is a rare, congenital syndrome characterised by the association of (1) congenital melanocytic nevi (CMN) of the skin with overlying hypertrichosis, presenting as (a) large (LCMN) or giant and/or multiple (MCMN) melanocytic lesions (or both; sometimes associated with smaller "satellite" nevi) or (b) as proliferative melanocytic nodules; and (2) melanocytosis (with infiltration) of the brain parenchyma and/or leptomeninges. CMN of the skin and leptomeningeal/nervous system infiltration are usually benign, more rarely may progress to melanoma or non-malignant melanosis of the brain. Approximately 12% of individuals with LCMN will develop NCM: wide extension and/or dorsal axial distribution of LCMN increases the risk of NCM. The CMN are recognised at birth and are distributed over the skin according to 6 or more patterns (6B patterns) in line with the archetypical patterns of distribution of mosaic skin disorders. Neurological manifestations can appear acutely in infancy, or more frequently later in childhood or adult life, and include signs/symptoms of intracranial hypertension, seizures/epilepsy, cranial nerve palsies, motor/sensory deficits, cognitive/behavioural abnormalities, sleep cycle anomalies, and eventually neurological deterioration. NMC patients may be symptomatic or asymptomatic, with or without evidence of the typical nervous system changes at MRI. Associated brain and spinal cord malformations include the Dandy-Walker malformation (DWM) complex, hemimegalencephaly, cortical dysplasia, arachnoid cysts, Chiari I and II malformations, syringomyelia, meningoceles, occult spinal dysraphism, and CNS lipoma/lipomatosis. There is no systemic involvement, or only rarely. Pathogenically, single postzygotic mutations in the NRAS (neuroblastoma RAS viral oncogene homologue; MIM # 164790; at 1p13.2) proto-oncogene explain the occurrence of single/multiple CMNs and melanocytic and non-melanocytic nervous system lesions in NCM: these disrupt the RAS/ERK/mTOR/PI3K/akt pathways. Diagnostic/surveillance work-ups require physical examination, ophthalmoscopy, brain/spinal cord magnetic resonance imaging (MRI) and angiography (MRA), positron emission tomography (PET), and video-EEG and IQ testing. Treatment strategies include laser therapy, chemical peeling, dermabrasion, and surgical removal/grafting for CMNs and shunt surgery and surgical removal/chemo/radiotherapy for CNS lesions. Biologically targeted therapies tailored (a) BRAF/MEK in NCM mice (MEK162) and GCMN (trametinib); (b) PI3K/mTOR (omipalisib/GSK2126458) in NMC cells; (c) RAS/MEK (vemurafenib and trametinib) in LCMNs cells; or created experimental NMC cells (YP-MEL).