UNASSIGNED: Melanocytic nevi can show a great number of morphological, cytoarchitectural, and stromal variations. Some of these histopathological patterns, infrequent or unusual, can occasionally produce diagnostic doubts or problems. A 22-year-old female patient presented a poorly pigmented cutaneous polypoid lesion of the scalp. Histopathological examination showed an intradermal melanocytic nevus composed of aggregates, nests, and cords of benign melanocytes, with collagenous stroma and large lipomatous areas. In the lipidized portion of the lesion, nevus cells, arranged in clusters, nests, and cords, were intimately associated with mature-appearing adipocytes, CD34-positive spindle cells, Alcian Blue-positive fibromyxoid stroma, and eosinophilic collagen bundles, findings resembling those typically seen in spindle cell lipoma. Spindle cell lipomatous metaplasia, rarely observed in some benign nonmelanocytic skin lesions, can be considered an additional unusual, not previously described, stromal variation occurring in melanocytic nevi.

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BACKGROUND: Childhood and adolescence are dynamic period in terms of nevogenesis, and the development and growth of new melanocytic nevus are frequently observed. In this study, the aim was to examine the pattern and diameter changes seen in the follow-up of pediatric melanocytic nevus.
OBJECTIVE: To describe the pattern and diameter changes seen in the follow-up of pediatric melanocytic.
METHODS: Our study involved the assessment of 301 pediatric melanocytic nevi in 50 patients attended at the Dermatology Clinic of Istanbul Training and Research Hospital between January 2008 and 2022. The pediatric melanocytic nevi were diagnosed clinically and dermoscopically. Subsequently, we conducted video-dermoscopic monitoring of these nevi over a span of 3 months to 3 years.
RESULTS: 46% of our patients were female (n = 23), with a mean age of 11.5 years. While the pattern of nevi was globular in 40% patients, the rate of globular pattern decreased to 30% in the follow-up. The basal homogeneous nevus pattern was seen in 10% patients, but was detected in 13.9% in the follow-up. Peripheral globules were observed in 19.3% of the cases, but in the follow-up, 61.1% of the globules regressed completely. Nevus excision was indicated in only 11 of 301 nevi.
CONCLUSIONS: Single-center study and a small of studies available on this subject.
CONCLUSIONS: Pediatric melanocytic nevi can show dynamic changes compared to nevi in adults. In this study, growth rates, dermoscopic features, and pattern changes seen in the follow-up of melanocytic nevi were evaluated. The globular pattern was observed most frequently. The presence of peripheral globules is frequently observed in pediatric melanocytic nevi with regression during the follow-up period.

OBJECTIVE: Congenital melanocytic nevi (CMN) and acquired nevi are prevalent in pediatric populations, with distinct characteristics and management considerations. This chapter aims to equip pediatricians with knowledge to discern between benign and high-risk nevi, facilitating appropriate referrals and management within primary care settings. Risk factors associated with malignant melanoma (MM) underscore the importance of vigilant monitoring and early referral to dermatology for suspicious lesions.
RESULTS: Recent findings highlight the variability in CMN presentation and the evolving diagnostic strategies, emphasizing the need for multidisciplinary approaches to optimize patient outcomes.
CONCLUSIONS: Management of CMN involves tailored surveillance and intervention strategies, with an emphasis on early identification of high-risk features for MM and neurocutaneous melanosis (NCM). Pediatricians play a crucial role in advocating for sun protection practices and facilitating timely referrals, thereby contributing to the overall well being of pediatric patients with nevi.

The clinical diagnosis of pigmented genital lesions is challenging. Reflectance confocal microscopy (RCM) is effective for diagnosis but is limited in its application due to elevated costs. A more affordable dermatoscope with a 400x magnification (D400) has recently been brought to market. The aim of our study was to compare these two imaging techniques for the analysis of pigmented genital tumours. An observational, prospective and mono-centric study was carried out from October 2017 to May 2019, in which clinical, dermatoscopic (20x and 400x) and RCM data from 207 pigmented genital lesions were collected. The images generated via D400 and RCM were analysed by three expert investigators. Similarities between the criteria observed using D400 and RCM were evaluated by each investigator. In total, 207 lesions were included: 183 melanosis, 19 nevi, one basal cell carcinoma (BCC), two condylomas and two melanomas in situ. Our series correlates well with data found in the literature especially for the distribution of different lesions, their topography, and their aspect using x20 dermatoscopy and RCM. Pattern and cell criteria defined using RCM largely paralleled those observed with D400 for all three investigators. Correlation between D400 and RCM was moderate to strong with regards to the identification of the ring pattern and clustered round cells, strong for dendritic and plump cells, and perfect for isolated round cells and spindle cells. D400 is an easy-to-use, cost-effective alternative for the analysis of pigmented genital lesions, particularly for melanosis.

BACKGROUND: Melanocytic nevi typically appear in early childhood, and their removal is a common plastic surgery procedure performed on children. However, the epidemiological characteristics and hospitalization burden of children with melanocytic nevi have rarely been described in detail.
METHODS: Medical records of pediatric inpatients with melanocytic nevi from January 1, 2016, to December 31, 2021, were collected from the Futang Research Center of Pediatric Development database in China. We then extracted and statistically analyzed the relevant information, including demographic characteristics, clinical information, hospitalization burden, and other basic information for each inpatient.
RESULTS: Among the 13,396 inpatients with melanocytic nevi, the highest number of cases was found in East China, and most patients were residents of urban areas. Most hospitalized patients consisted of boys aged 7-12 years with melanocytic nevi. Lesion sites in the buttocks and lower limbs were most common among pediatric inpatients with melanocytic nevi. Compound nevi were the most common (38.50 %) histological subtype and the rate of conversion into melanoma was 1.02 % (137 inpatients) among pediatric inpatients with melanocytic nevi. The hospitalization burden for patients varied significantly based on factors such as the age of the patients undergoing surgery, year of hospitalization, site of the lesion, histological subtype, and surgical method. In general, if the patients\' age was under 1 year, lesion site was located in face, and there was a need for excision combined with tissue expander can significantly increase the treatment fees for pediatric inpatients with melanocytic nevi.
CONCLUSIONS: Given the increasing number and relatively large hospitalization burden among children with melanocytic nevi hospitalized in China, the government needs to pay more attention to this group and provide corresponding economic and policy support.

BACKGROUND: The Preferentially Expressed Antigen in Melanoma (PRAME) immunostain has seen significant diagnostic use in confirming malignancy for melanocytic lesions. However, the expression of PRAME in genital melanocytic lesions have not been reported. In this study, PRAME staining was performed on a cohort of genital melanocytic lesions, aiming to investigate the diagnostic role of PRAME in genital melanocytic lesions and its expression in atypical genital nevi.
METHODS: A cohort including genital invasive melanoma, melanoma-in-situ, atypical genital nevus (AGN), compound nevus, intradermal nevus, blue nevus, lentigo and melanosis was retrieved with histology reviewed and PRAME immunostaining performed.
RESULTS: A total of 66 cases were reviewed. The average proportion expression of PRAME were 56.75 % and 57.43 % for invasive melanoma and melanoma-in-situ, with average H-scores of 153.5/300 and 163.14/300 respectively, which were greater than AGN (3.25 %, 7.75/300, p<0.001), compound/intradermal nevi, lentigo/melanosis, and background junctional melanocytes (<1 %, <1/300, p<0.001). The different cutoffs of PRAME expression, the sensitivity and specificity were 65.22 % and 100 % (>100/300); 69.57 % and 95.83 % (>10/300); and 82.61 % and 93.75 % (≥1/300) respectively. Low level PRAME expression was seen in half of the cases of AGN (n=2/4, 50 %), and at low cutoffs (>10/300 and ≥1/300) unable to differentiate invasive melanoma from AGN (p>0.05).
CONCLUSIONS: For genital melanocytic lesions, PRAME immunostain shows high specificity at strong and diffuse staining. AGN not uncommonly display low level expression. Focal and/or weak PRAME expression should not be considered as an absolute indication of malignancy, and comprehensive histological assessment remains the key to accurate diagnosis of melanocytic lesions.

BACKGROUND: To date, only a limited number of case reports have documented the co-occurrence of PNS and melanocytic nevus in the medical literature. This study aims to report an exceptionally rare case of posterior chest wall PNS in conjunction with a melanocytic nevus.
METHODS: A 46-year-old female presented with a long-standing black lesion on her left upper posterior chest wall, that had become painful in the two months prior to presentation. There was a painful, dark blue, non-erythematous, and non-tender nodule on the left upper posterior chest wall. Based on the patient\'s desire for cosmetic purposes, the lesion was excised totally with primary closure under local anaesthesia. Histopathological examination revealed intradermal melanocytic nevus with inflamed pilonidal sinus.
CONCLUSIONS: The rarity of posterior chest wall PNS associated with nevi poses unique diagnostic and therapeutic challenges for clinicians. The distinct anatomical location, different from the conventional region, and the rare association between the two conditions may delay accurate diagnosis and result in mismanagement or inappropriate interventions.
CONCLUSIONS: The posterior chest wall PNS is another type of atypical PNS that is extremely rare. The association between PNS and blue nevus is a fascinating medical finding that deserves further investigation.

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