Lipomatous Congenital Melanocytic Nevus Presenting as a Neck Mass in a Young Adult

Congenital melanocytic nevus is a inborn melanocytic proliferation either present since birth or soon afterward and shows characteristic histopathological features comprising proliferation of benign melanocytes and extension of nevus cells...

As only few previous investigations considered size-dependent differences in the histology of congenital nevocytic nevi (CNN) or focused on their ultrastructure, a light- and electron-microscopic study of six giant and six medium-sized CNN was performed. Histologically, giant CNN showed minimal junctional nevus elements and a pandermal, diffuse nevus cell extension including the subcutaneous tissue, while medium-sized CNN exhibited more abundant junctional nests and a rather focal pattern of nevus cell extension into the reticular dermis. Ultrastructurally, giant CNN often showed nevus cells with irregular and indented nuclei and also nevus cells with highly complicated dendrites. Nuclear inclusions, multiple cilia and centrioles, and collagen phagocytosis in nevus cells were found in both groups of CNN. Direct contacts between nevus cells and nerve fibers were observed in medium-sized CNN only. The findings provided no clear morphological indication why giant CNN have a higher risk for malignant degeneration than medium-sized CNN or acquired nevocytic nevi (ANN). On the other hand, the histological differences speak in favor of a different ontogenesis of the various size classes of CNN and ANN.

An Unusual Pigmented Plaque in a Newborn.

Next-Generation Sequencing of Nevus Spilus–Type Congenital Melanocytic Nevus: Exquisite Genotype–Phenotype Correlation in Mosaic RASopathies

Congenital melanocytic nevi are melanocytic nevi that have their onset at birth or during the first 2 years of life. They are relatively common with an incidence among newborns ranging between 0.2% and 6% (Zayour and Lazova R, Clin Lab Med 31:267–280, 2011). There is a female predominance. Congenital melanocytic nevi initially present as pigmented macules or slightly raised oval papules or plaques. They usually darken over time and become raised or verrucous. Congenital melanocytic can display a wide variety of colors ranging from light brown to black. Hypertrichosis is commonly observed. Congenital melanocytic nevi usually grows proportionally with the child. They are classified according to their estimated adult size as small (<1.5 cm), medium (1.5–20 cm), large or giant (>20 cm) (Navarro-Fernandez and Mahabal, Congenital nevus, 2020). Giant nevi occasionally show satellite smaller lesions. Congenital melanocytic nevi may be associated with melanocyte proliferation in the central nervous system. Large lesions have a higher risk of melanoma development. Congenital melanocytic nevi are usually diagnosed based on the clinical appearance. Dermoscopy or punch biopsy for histopathological examination may be used in cases of diagnostic doubt. Treatment options may be divided into surgical and non-surgical. Non-surgical therapeutic options include dermal abrasion, chemical peels, cryotherapy, electrosurgery, and ablative lasers.KeywordsCongenital melanocytic nevusDermoscopyMelanocyteMelanomaNeviScalp

NRAS Mutation Is the Sole Recurrent Somatic Mutation in Large Congenital Melanocytic Nevi

Objective Present treatment in plastic surgery on giant congenital melanocytic nevus has always been a tough practice because it is difficult to achieve balance between effects and costs of treatment.This paper aimed to explore the concrete procedure of tangential excision and dermabrasion in treatment of adult giant congenital melanocytic nevus. Methods Taking into consideration pathological examination results before surgery,diseased regions,psychological expectancy and other factors,we used a humby knife or globe grinding head to remove giant congenital relanocytic nevus by wiping off the surface of it in 10 cases.After operation,the operated area of the skin underwent a process of healing in a moisturized state.In each case,surgical procedure was carried out by 1 2 sta ges,with the interval period ranges from 3 months to 6 months.Results One to 3 years follow-ups showed that among those cases,5 cases obtained good results in which skin color of surgical area turned to normal and pathological examination showed that nevus cells disappeared,4 cases achieved improvement,and 1 case was relapsed.Conclusions The two alternative methods for treatment of giant congenital melanocytic nevus,either tangential excision or dermabrasion,with combination of pathological examination results,diseased regions,and psychological expectancy should be taken into consideration,which can remain a maximum balance between effects and costs of treatments.Tangential excision and dermabrasion are effective in some cases of giant congenital nevus where traditional methods do not work,or in order to reduce the cost of body appearance in treatment.Therefore,these two methods deserve to be adopted extensively in clinical therapy.But it still needs further accumulation of experience in practice and longer period of follow-up after operation. Key words: Giant congenital melanocytic nevus; Tangential excision; Dermabrasion

The major diagnostic criterion for the giant congenital melanocytic nevus (GCMN) is a size larger than 20 cm in diameter. However, the histopathological origin, pathogenesis, and GCMN progression are not yet completely clear. Unlike other medium or small superficial lesions, histomorphological evaluation is significant for GCMN pathological classification, malignant transformation assessment, and early detection of prognosis. This study aimed to investigate the pathological features of GCMN, including its satellite lesions. Twenty-three giant naevi and seventeen "satellite lesions" were collected from children aged 1 to 10 in Shanghai Ninth People's Hospital from 2018 to 2020. A histological study was conducted to evaluate their histological appearance. All the data observed and recorded data were statistically analyzed. In 23 cases of GCMN primary nevus, nevus cells were mainly distributed in the dermal region, with melanocyte proliferation and the presence of nevus nests at the dermal-epidermal junction. However, in satellite nevus, a junctional growth pattern was noted. Additionally, other histopathologic features, including epidermal contour, cell morphology, and architecture disorder also showed significant differences between primary nevus and satellite nevus. We demonstrated that the congenital pattern of the main nevus is more obvious than one of the satellite nevus, suggesting that the satellite nevus and the main nevus may occur slightly later than the main nevus. "Satellite nevus" happens as a result of a separate genetic event.

Since Unna's Abtropfung hypothesis, the process of migration of nevus cells in the dermis remains unknown. To investigate its mechanisms, we studied the role of gelatinases in dermal nevus cells obtained from congenital pigmented nevi, which are major actors in the remodeling of basement membrane proteins. Our previous studies have shown that dermal nevus cells express pro-matrix metalloproteinase (MMP)-2 exclusively and cannot return to the dermis when seeded together with keratinocytes on top of the dermis in a skin reconstruction model. To examine why MMP-2 was not in its active form, we used Western blot to study the expression of members of the MMP-2 activation pathway (membrane type 1-MMP and tissue inhibitor of metalloproteinase-2), which proved to be normally expressed. To induce the dermal passage of nevus cells artificially, we also tried to activate gelatinases with phorbol-12-myristate-13-acetate and epidermal growth factor, using epidermis reconstructed with nevus cells. No migration in the dermis could be triggered. We conclude that the absence of active MMP-2 is due to a functional blockade of its activation pathway and may prevent dermal nevus cells from reaching the dermal compartment in skin reconstructs. Furthermore, our findings reinforce the concept that dermal nevus cells originating from congenital nevi are in a quiescent status.

The histogenesis of melanocytic nevi is poorly understood. It is important to determine the differences and similarities in histogenesis between congenital and acquired nevi. To clarify the histogenic differences between acquired melanocytic nevi (AMN) and congenital melanocytic nevi (CMN), diameter and depth of nevus cells (tumor thickness) were examined in histological specimens from 80 cases of CMN and 71 cases of AMN, and these nevi were classified according to Mark's pathological CMN criteria. In all cases, giant CMN nevus cells were found in the lower marginal portion of excised specimens. The mean diameter and lesional thickness were significantly higher in CMN than in AMN. AMN diameter showed a significant correlation (r = 0.567, P < 0.05) with lesional thickness, while no such relation was observed in CMN. In addition, a significant correlation between lesion diameter and thickness was observed in small (<10 mm) non-Mark's type CMN (r = 0.626, P < 0.05). CMN may be classified into three subtypes: (i) caused by increased proliferation of melanoblasts during the course of migration from the neural crest to the epidermis; (ii) proliferation of nevus cells after arrival at the epidermis, and nevus cell distribution affected by adnexa and dermal differentiation; and (iii) arising after completion of skin development before birth.

Congenital melanocytic nevi (CMN), arising from the proliferation of melanocytes, manifest at birth and are colloquially termed as bathing trunk, coat-sleeve, or stocking nevi. These lesions, occurring in approximately 1 to 2% of neonates, predominantly localize over the trunk and thigh regions. Giant congenital nevi, characterized by a size exceeding 20 cm, often present with pigmentation and hairiness. Herein, we present the case of a 14-year-old patient diagnosed with a giant congenital nevus (bathing trunk nevus) accompanied by lipomatosis, while concurrently reviewing the literature to delineate this rare association. Our investigation identified a total of six cases, comprising five females and one male. Notably, half of the cases (3/6) exhibited multiple lipomatous lesions, with the back region emerging as the most prevalent site. In our presented case, progressive enlargement of a soft tissue mass in the right flank prompted excision, revealing a well-circumscribed lipomatous lesion infiltrated diffusely by benign-appearing melanocytes within fat lobules, as confirmed by immunohistochemistry. Specifically, positivity for HMB45 and S100 markers was observed. Beyond the rarity of such occurrences, our report underscores the infrequent concomitance of CMN with lipomatosis.

Giant congenital melanocytic nevi (CMN) are rare, congenital, disfiguring lesions with a risk of degeneration to malignant melanoma. Giant CMN are associated with an increased risk of malignant degeneration. In a minority of cases, patients with giant CMN may have associated neurocutaneous melanosis with leptomeningeal involvement. Giant CMN of the trunk pose difficult diagnostic and reconstructive problems requiring complex multistage treatment. For high-risk cases, diagnostic evaluation in the form of neuro-imaging is an essential component of the planning phase. Although nonsurgical options for the treatment of giant CMN have been advocated, these modalities may decrease the burden of nevus cells but do not result in complete removal of these cells. The ability to monitor nevus cells that remain after nonsurgical management of giant CMN remains questionable. These nonsurgical options include dermabrasion, laser ablation, and chemical peel. In contrast, direct excision of the nevus is the mainstay of treatment of nonsurgical management of giant CMN. There are numerous surgical options to resurface the resultant cutaneous defect after excision of the nevus. The simplest of these options consists of serial excision and direct closure of the defect in stages. However, if the defect cannot be closed by direct cutaneous advancement, other options for wound resurfacing include split- or full-thickness skin graft, tissue expansion, and free tissue transfer. Tissue expansion should be viewed as a category of treatment options because expanders can be used to create an expanded full-thickness skin graft, local expanded flaps adjacent to the lesion, or expansion of a free tissue donor site. Given the diversity of reconstructive options that use tissue expansion, these techniques have evolved as the primary treatment method for giant CMN of the trunk. The authors outline an approach to the evaluation of giant CMN of the trunk, review the risks of melanoma and of neurocutaneous melanosis, describe their preferred treatment regimen, and offer a treatment algorithm for giant CMN of the trunk.

Patients with congenital nevus, especially giant congenital melanocytic nevus (CMN) measuring >20 cm, are known to be at elevated risk of developing melanomas, especially during the first and second decades of life. Melanomas rarely develop in patients with small and medium-sized CMNs, but if they do, they occur during the fourth and fifth decades of life. We present a case of a rapidly enlarging signet-ring cell melanoma (over 3 months) that arose from a medium-sized CMN in a 57-year-old Japanese man. Only 11 other cases of signet-ring cell melanomas at the primary site have been reported. On the basis of morphology alone, it is difficult to diagnose a nodule appearing in a CMN as a signet-ring cell melanoma, because even a benign melanocytic nevus can appear as signet-ring cell morphology. Moreover, a rapidly growing proliferative nodule (PN) more often develops in a CMN than melanoma; PNs may at times exhibit enough atypia to be comparable to melanomas. In our case, loss of p16 expression in the melanoma distinguished it from the nevus cells and was helpful in making the correct diagnosis. Clinical information, such as the patient's age, was also useful in establishing the diagnosis.

Neurocristic Cutaneous Hamartoma With Perineuriomatous Differentiation: Can It Be Distinguished From Perineuriomatous Melanocytic Nevi?

Neurofibromas are often clinically, as well as histologically, indistinguishable from completely neurotized melanocytic nevi. We tested the hypothesis that immunologic markers would differentiate the perineural fibroblasts and Schwann cells of neurofibromas from the neurotized cells of melanocytic origin. We examined eight partially neurotized acquired melanocytic nevi, three partially neurotized congenital melanocytic nevi, and five neurofibromas, with antibodies directed against S-100 protein, Leu-7(HNK-1), glial fibrillary acid protein (GFAP), and myelin-basic protein (MBP). A histologic diagnosis of neurofibroma was based on identification of a dermal proliferation of spindle-shaped cells with wavy nuclei, in a background of loose reticulated collagen. Neurotized nevi were diagnosed upon recognition of scattered nests of type A or B nevus cells, surrounded by basement membrane, present in the papillary dermis of lesions otherwise indistinguishable from neurofibromas. The congenital nevi were all large melanocytic nevi known to be present at birth. S-100 stained the majority of neoplastic cells in all neurofibromas, neurotized acquired nevi, and neurotized congenital nevi. Neurofibromas showed focal staining for Leu-7, GFAP, and MBP. In contrast, neurotized acquired and congenital nevi failed to express these markers. We believe that Leu-7, GFAP, and MBP may be helpful in differentiating neurofibromas from completely neurotized melanocytic nevi. The differences in the immunohistochemical profiles of neurofibromas and neurotized nevi support the concept that these neoplasms are histogenically distinct, despite their similar histologic appearance.