Pediatric “STUMP” lesions: Evaluation and management of difficult atypical Spitzoid lesions in children

Diagnostic Algorithm to Subclassify Atypical Spitzoid Tumors in Low and High Risk According to Their Methylation Status

Current diagnostic algorithms are insufficient for the optimal clinical and therapeutic management of cutaneous spitzoid tumors, particularly atypical spitzoid tumors (AST). Therefore, it is crucial to identify new markers that allow for reliable and reproducible diagnostic assessment and can also be used as a predictive tool to anticipate the individual malignant potential of each patient, leading to tailored individual therapy. Using Reduced Representation Bisulfite Sequencing (RRBS), we studied genome-wide methylation profiles of a series of Spitz nevi (SN), spitzoid melanoma (SM), and AST. We established a diagnostic algorithm based on the methylation status of seven cg sites located in TETK4P2 (Tektin 4 Pseudogene 2), MYO1D (Myosin ID), and PMF1-BGLAP (PMF1-BGLAP Readthrough), which allows the distinction between SN and SM but is also capable of subclassifying AST according to their similarity to the methylation levels of Spitz nevi or spitzoid melanoma. Thus, our epigenetic algorithm can predict the risk level of AST and predict its potential clinical outcomes.

Melanoma in children: A systematic review and individual patient meta-analysis

The current evidence on paediatric melanoma is heterogeneous, especially regarding the prognosis of different histological subtypes. We sought to systematically review the evidence on paediatric melanoma, highlighting the major sources of heterogeneity and focusing on available data on single patients. A systematic search was performed from 1948 to 25 January 2021. Only studies reporting at least one case of cutaneous melanoma in patients aged ≤18 years were included. Unknown primary and uncertain malignant melanomas were excluded. Three couples of authors independently performed title/abstract screening and two different authors reviewed all the relevant full texts. The selected articles were manually cross-checked for overlapping data for qualitative synthesis. Subsequently data on single patients were extracted to perform a patient-level meta-analysis. PROSPERO registration number: CRD42021233248. The main outcomes were melanoma-specific survival (MSS) and progression-free survival (PFS) outcomes. Separate analyses were done of cases with complete information on histologic subtype, focusing on superficial spreading (SSM), nodular (NM) and spitzoid melanomas, as well as of those classified as de-novo (DNM) and acquired or congenital nevus-associated melanomas (NAM). The qualitative synthesis covered 266 studies; however, data on single patients were available from 213 studies including 1002 patients. Among histologic subtypes, NM had a lower MSS than both SSM and spitzoid melanoma, and a lower PFS than SSM. Spitzoid melanoma had a significantly higher progression risk than SSM and trended toward lower mortality. Focusing on nevus-associated status, DNM demonstrated better MSS after progression than congenital NAM, and no differences were highlighted in PFS. Our findings describe the existence of different biological patterns in paediatric melanoma. Specifically, spitzoid melanomas demonstrated intermediate behaviour between SSM and NM and showed a high risk of nodal progression but low mortality. This raises the question of whether spitzoid lesions are being over-diagnosed as melanoma in childhood.

The spectrum of melanocytic nevi and their clinical implications

The magnitude of the topic of melanocytic nevi (MN) is directly related to its relevance in everyday clinical work. The different MN have different prognostic significance in regard to comorbidity and possible risk of transformation. In addition to the criteria of the ABCDE rule, relevant criteria in the assessment of an MN are the time of occurrence, the growth tendency, the distribution and the comparison with other MN of the respective individual.

The present CME article provides an overview of the knowledge that has been gained with regard to the development and genetic background of MN and any risk of degeneration that may exist. In addition, certain clinical and/or dermatoscopic features may provide the clinician with a decision‐making aid in the management of different MNs.

Risk factors for the development of Spitz neoplasms

BACKGROUND/OBJECTIVES

The principal environmental risk factor for conventional nevi and melanomas is ultraviolet exposure. However, little is known about genetic or environmental risk factors for developing Spitz tumors. This study investigates risk factors associated with Spitz neoplasms.

METHODS

Patients with Spitz tumors seen at Northwestern Memorial Hospital and Lurie Children's Hospital were surveyed with a 16-item questionnaire about environmental and inherited factors. Spitz tumor patients were compared to a pediatric control cohort from a similar clinical setting. This was supplemented with a meta-analysis of genetic and environmental causes of Spitz neoplasms.

RESULTS

One hundred and six Spitz and 58 control surveys were obtained and no statistically significant differences in genetic or environmental risk factors were found between Spitz and control groups.

CONCLUSION

Our data and meta-analysis suggest that typical risk factors associated with melanoma are not significantly associated with Spitz tumors. Identification of relevant genetic or environmental risk factors will likely require larger and population-based studies.

Pediatric melanoma in the Hispanic population: An analysis of institutional and national data

BACKGROUND/OBJECTIVES

Pediatric melanoma is rare and remains poorly characterized, especially in racial/ethnic minorities of whom Hispanics are the largest and fastest growing in the United States. The health care burden of melanoma in Hispanics, who often present with more advanced disease, is rising and has even been called an early epidemic in California. We sought to document key clinicopathologic features of melanoma in Hispanic pediatric patients and to compare these parameters to pediatric non-Hispanic whites (NHWs) under the a priori hypothesis that Spitzoid melanomas occur in greater proportions in Hispanics.

METHODS

Single-institution cross-sectional study of pediatric melanoma cases (age < 20 years) with Hispanic stratification and comparison with matched Surveillance, Epidemiology, and End Results (SEER) data from the same time frame (1988-2016).

RESULTS

Of our 61 institutional cases of pediatric melanoma, Hispanics (11), compared with NHWs (40), presented significantly younger (11.7 years, 95% CI: 2.77-8.00 years; P = .001), with lower limb predominance (46%; P < .05), mostly Spitzoid melanomas (82%; P < .05), and thicker tumors (2.34 mm, CI: 0.26-2.19 mm; P < .05). Similarly, SEER data (2499 cases) showed greater proportions of childhood/pre-pubertal adolescent melanomas (<15 years), lower limb involvement, Spitzoid subtype (36.5% vs 22.5% in NHWs; P = .001), and advanced (regional/distant) disease stages in Hispanics (212) compared with NHWs (2197).

CONCLUSIONS

Pediatric melanomas may present differently in Hispanics, and heightened awareness/lower threshold to biopsy high-risk Spitzoid tumors on the lower limb may be warranted. Further investigations are needed to aid prevention and early detection in a vulnerable minority population less likely to seek outpatient dermatology specialty care.

Age and Melanocytic Lesions

Age plays a dynamic role in incidence, presentation, and extent of disease for cutaneous melanoma. Even within the spectrum of juvenile melanoma, there exists a range of spitzoid and nonspitzoid melanocytic and melanoma lesions. Spitzoid melanomas, a more favorable disease in juvenile patients, are malignant lesions and require treatment as such. Lymph node metastases in melanoma occur at lower rates in older patients compared with younger counterparts, yet the rate of metastases is still high. Age appears to play an important role in the development and progression of melanoma, and understanding the differences across age populations is important when counseling patients.

A sixteen-year single-center retrospective chart review of Spitz nevi and spitzoid neoplasms in pediatric patients

BACKGROUND

Spitzoid neoplasms in pediatric patients pose an interesting challenge for clinicians. More data on the clinical, histologic, and molecular characteristics of these lesions are necessary to distinguish features that may portend recurrence or malignant behavior to help determine future treatment guidelines in pediatric patients.

METHODS

Institutional Review Board approval was obtained from Children's Hospital of Wisconsin to conduct a retrospective analysis of spitzoid neoplasms. Patients with biopsied or excised spitzoid neoplasms between 01/01/2000 and 08/01/2016 were included. Pertinent clinical and histologic data were collected. Atypical, unusual, or diagnostically uncertain lesions were selected for re-review.

RESULTS

266 lesions from 264 patients were included. 243 were classified as benign (91.35%), 22 as atypical (8.27%), and 1 as spitzoid melanoma (0.38%). No clinical or histologic variables were found to be statistically significant between the benign Spitz, atypical Spitz, and spitzoid melanoma cohorts. No known deaths occurred.

CONCLUSION

Our findings highlight the extreme variability of spitzoid neoplasms clinically and histologically. Importantly, this study demonstrates that the vast majority of spitzoid neoplasms in pediatric populations are benign and supports conservative management of spitzoid lesions in children.

Spitz Nevus and Other Spitzoid Tumors in Children. Part 2: Cytogenetic and Molecular Features. Prognosis and Treatment

Melanocytic neoplasms with spitzoid morphology (Spitz nevi, atypical Spitz tumors, and spitzoid melanomas) may be benign or malignant. Because the malignant potential of atypical Spitz tumors is uncertain, the proper therapeutic approach has been much debated over the years. Promising new techniques for molecular analysis have enabled better predictions of the biological behavior of these tumors. We review their cytogenetic features and prognosis and also provide an update of the most recent recommendations for management.

Invasive melanoma in a 5-year-old Canadian patient: A case report

Atypical Spitzoid lesions pose a distinct challenge in classification as they may comprise a mixture of both classic benign nevus and cutaneous melanoma characteristics. Immunostaining and molecular analysis, such as comparative genomic hybridization, can assist in narrowing the differential diagnosis. We present a case of a 5-year-old male with an atypical Spitzoid lesion on his back. Initial histopathology revealed a relatively symmetric lesion with mitotic figures and poor maturation of melanocytes with descent into the dermis. Immunohistochemistry demonstrated a loss of p16, and array comparative genomic hybridization revealed a loss of chromosome 9, supporting a diagnosis of invasive melanoma arising in conjunction with a remnant of a conventional melanocytic nevus. This case is the first in Canada to demonstrate the use of array comparative genomic hybridization for diagnosing melanoma in a young paediatric patient.

Genomic Landscape of Spitzoid Neoplasms Impacting Patient Management

Spitzoid neoplasms are a distinct group of melanocytic proliferations characterized by epithelioid and/ or spindle shaped melanocytes. Intermediate forms that share features of both benign Spitz nevi (SN) and Spitz melanoma, i.e., malignant Spitz tumor (MST) represent a diagnostically and clinically challenging group of melanocytic lesions. A multitude of descriptive diagnostic terms exist for these ambiguous lesions with atypical Spitz tumor (AST) or Spitz tumor of uncertain malignant potential (STUMP) just naming two of them. This diagnostic gray zone creates confusion and high insecurity in clinicians and in patients. Biological behavior and clinical course of this intermediate group still remains largely unknown, often leading to difficulties with uncertainties in clinical management and prognosis. Consequently, a better stratification of Spitzoid neoplasms in benign and malignant forms is required thereby keeping the diagnostic group of AST/STUMP as small as possible. Ancillary diagnostic techniques such as immunohistochemistry, comparative genomic hybridization, fluorescence in situ hybridization, next generation sequencing, micro RNA and mRNA analysis as well as mass spectrometry imaging offer new opportunities for the distinct diagnosis, thereby allowing the best clinical management of Spitzoid neoplasms. This review gives an overview on these additional diagnostic techniques and the recent developments in the field of molecular genetic alterations in Spitzoid neoplasms. We also discuss how the recent findings might facilitate the diagnosis and stratification of atypical Spitzoid neoplasms and how these findings will impact the diagnostic work up as well as patient management. We suggest a stepwise implementation of ancillary diagnostic techniques thereby integrating immunohistochemistry and molecular pathology findings in the diagnosis of challenging ambiguous Spitzoid neoplasms. Finally, we will give an outlook on pending future research objectives in the field of Spitzoid melanocytic lesions.

Pigmented Kamino bodies: a little-known histological finding. Prevalence in 19 cases of Reed nevus

The present study aimed to determine the prevalence of Kamino bodies in Reed nevus, since most studies to date show conflicting data on this issue. This was a retrospective observational study, in which the histopathology of 19 Reed nevus lesions were reviewed. The slides were stained by hematoxylin and eosin and periodic acid-Schiff, with a special focus placed on the identification of Kamino bodies. Some clinical data were also collected. The median patient age was 12 years (range of 2 to 58). The women to men ratio was 5:4. Lesions were located on different parts of the body. Kamino bodies were found in eleven lesions (57.89%). five showed pigmented Kamino bodies (26.31%), four non-pigmented Kamino bodies (21,05%), and 2 (10.52%) had both. Kamino bodies, pigmented or not, are a common histological finding in Reed nevus and may well represent a good marker to differentiate these from malignant melanomas.

The large spectrum of Spitzoid tumors: a retrospective survival study

BACKGROUND

There is no universally-accepted classification of Spitzoid tumors. This makes it difficult to assign a correct diagnosis and select a treatment that minimizes the risk of overestimating, or worse, underestimating, the malignant potential of these tumors. The aim of this study was to describe the clinical-pathological and epidemiological features of Spitzoid tumors, as well as to assess mortality in these patients.

METHODS

This retrospective cohort study looked at data on Spitzoid tumors excised in 1999-2012 at the Dermatologic Clinic of the Turin University Hospital. Spitzoid melanoma specific survival curves were generated with the Kaplan-Meier method and compared using the log-rank test.

RESULTS

In this time period, 1663 lesion were described at the pathologic report as Spitzoid. 262 (15.75%) were Spitz nevi, 307 (18.46%) Reed nevi, 827 (49.73%), 810 (48.71%) Spitzoid dysplastic nevi, 17(1.02%) atypical Spitzoid tumors, and 267 (16.06%) Spitzoid melanomas. Median follow-up time was 9 years. Out of the entire cohort only 24 patients died from melanoma. All of them received a diagnosis of Spitzoid melanoma. None of the patients with a diagnosis of not melanoma Spitz tumor died for melanoma during the follow-up.

CONCLUSIONS

In the large majority of the cases, Spitz tumor should be considered as benign lesion and excised only if melanoma features are seen. The used clinical pathological classification avoid misdiagnoses, inappropriate treatment and the risk of death for melanoma.

Paediatric melanoma

Paediatric melanoma, although rare, is the most common skin cancer in children. Our current knowledge on paediatric melanoma incidence trends is expanding, as several studies have addressed this issue with conflicting results. Known risk factors for paediatric melanoma include family history of melanoma, a previous history of malignancy, large congenital nevi, numerous melanocytic nevi, sunburns, increased UV exposure and a sun-sensitive phenotype. In younger children, melanoma more often presents with atypical features, such as a changing, amelanotic or uniformly coloured, often bleeding lesion, not fulfilling in most cases the conventional ABCDE criteria. The major differential diagnoses are melanocytic nevi, proliferative nodules in congenital nevi and atypical Spitz tumours. Moreover, in the younger age group non-Caucasian children are over-represented, tumours tend to be thicker and lymph nodes are often involved. Despite the frequent diagnosis at an advanced stage, the overall survival is fair in paediatric melanoma. Specific guidelines for management of melanoma in children do not exist, and most often the disease is treated similarly to melanoma in adults.

Five-point checklist for skin cancer detection in primary care

BACKGROUND

Skin cancer screening interventions often relay on the involvement of general practitioners (GPs). Many interventions up to now have been directed to training approaches focusing on the clinical features of skin malignancies to increase GPs skill in skin cancer recognition.

METHODS

Based on the available current knowledge about skin cancer epidemiology and risk factors, we built up a 5-point checklist to help GPs in triaging patients to be referred to a dermatologist.

RESULTS

Five-point check-list: 1) visible sun damaged skin on exposed areas (red and brown to black macules and crusts on visible skin); 2) more than 20 nevi on the arms; 3) one or more ABCD positive lesions (flat, large and asymmetric macules); 4) one or more EFG positive lesions (elevated, firm and growing skin lesions); 5) a pigmented lesion larger than 1.5 cm in diameter.

CONCLUSIONS

Our aim was to provide a short list of practical rules, easy to adopt into a routine practice, in order to achieve a more effective triage of patients requiring a dermatology consultation for skin cancer examination. The novelty of the proposed method relies on the approach. The proposed method does not require the GP to diagnose skin cancer. The aim is to involve GPs in the selection of patients to be referred to the specialist, in order to reduce the waiting time while avoiding the risk to leave cancers untreated.

Imaging mass spectrometry assists in the classification of diagnostically challenging atypical Spitzoid neoplasms

BACKGROUND

Previously, using imaging mass spectrometry (IMS), we discovered proteomic differences between Spitz nevi and Spitzoid melanomas.

OBJECTIVE

We sought to determine whether IMS can assist in the classification of diagnostically challenging atypical Spitzoid neoplasms (ASN), to compare and correlate the IMS and histopathological diagnoses with clinical behavior.

METHODS

We conducted a retrospective collaborative study involving centers from 11 countries and 11 US institutions analyzing 102 ASNs by IMS. Patients were divided into clinical groups 1 to 4 representing best to worst clinical behavior. The association among IMS findings, histopathological diagnoses, and clinical groups was assessed.

RESULTS

There was a strong association between a diagnosis of Spitzoid melanoma by IMS and lesions categorized as clinical groups 2, 3, and 4 (recurrence of disease, metastases, or death) compared with clinical group 1 (no recurrence or metastasis beyond a sentinel node) (P < .0001). Older age and greater tumor thickness were strongly associated with poorer outcome (P = .01).

CONCLUSIONS

IMS diagnosis of ASN better predicted clinical outcome than histopathology. Diagnosis of Spitzoid melanoma by IMS was strongly associated with aggressive clinical behavior. IMS analysis using a proteomic signature may improve the diagnosis and prediction of outcome/risk stratification for patients with ASN.

Melanoma: Kids are not just little people

Malignant melanoma can affect patients of any age. It has been well documented that the overall incidence of melanoma has increased in the past several decades, and this increase extends to the pediatric population (both preadolescent and, to a greater extent, adolescent children). Melanoma in adolescents, commonly defined as patients 11 to 19 years of age, behaves similarly to melanoma in adults; however, there are a number of distinct differences in the presentation and prognosis of melanoma in the preadolescent population. Though our treatment options for melanoma are increasing with the advent of novel drugs and clinical trials, the rarity of pediatric melanomas often excludes this population from clinical studies. The treatment options for the pediatric patient are predominantly based on adult clinical trials. Awareness of the differences in clinical presentation, as well as management of melanoma in younger patients compared with their adult counterparts, is crucial to guarantee prompt and appropriate care.

The complex management of atypical Spitz tumours

In recent years, advances in molecular genetic characterisation have revealed that atypical Spitz tumours (ASTs) are basically heterogeneous diseases, although the clinical relevance of these findings is yet to be determined. Evidence of molecularly-defined diverse groups of lesions continues to accumulate; however, conflicting, confusing, and overlapping terminology has fostered ambiguity and lack of clarity in the field in general. The lack of fundamental diagnostic (morphological) unambiguous classification framework results in a number of challenges in the interpretation of the molecular genetic data. In this review, we discuss the main difficulties for pathologists and clinicians in the complex management of ASTs, with particular emphasis on the different genetic and biological features of recently-described entities, and offer our view of what could be medically reasonable to guide a rational approach in light of current data.

Case reports of fatal or metastasizing melanoma in children and adolescents: a systematic analysis of the literature

Childhood melanoma (ChM) is rare, with clinical and epidemiologic characteristics that differ from those of adult melanomas. The objective of the current study was to systematically identify and analyze case reports and case series of fatal and metastasizing ChM in the medical literature. ChM case reports with a fatal outcome or metastases were identified using a Medline search and subdivided into ChM developing in the absence of a congenital melanocytic nevus (ChM without CMN) and ChM associated with a CMN (ChM with CMN); 258 cases of ChM without CMN (206 cutaneous, 52 noncutaneous) were identified. In cutaneous ChM without CMN with a fatal outcome (n = 155), the mean age at diagnosis was 13.1 years (median 14 yrs). The mean Breslow index in this group was 8.5 mm for children ages 0 to 10 years and 3.7 mm for children ages 11 to 18 years. In ChM with CMN (n = 178; 112 cutaneous, 66 central nervous system [CNS]), the mean age at diagnosis was 5.8 years for cutaneous melanoma (median 3 yrs) and 5.5 years for CMN-associated CNS melanoma (median 3 yrs). The majority of CMN-associated cutaneous melanomas developed in small and giant CMN (vs medium and large); 53.9% of CNS melanomas developed in patients with multiple medium CMN. This study represents the largest and most complete synopsis of ChM case reports in the medical literature. Our analysis supports the view that cutaneous ChM without CMN (or associated with smaller CMN) differs in several important aspects from ChM associated with large or giant CMN.

Update on melanocytic nevi in children

A new or changing melanocytic nevus in a child or adolescent often leads to concern in parents and physicians. To avoid undue alarm and unnecessary procedures, dermatologists should be aware of the natural history and clinical spectrum of nevi in pediatric patients, as well as findings that are potentially worrisome in this age group. This review provides an update on melanocytic nevi in children, focusing on their dynamic evolution over time, molecular insights into nevogenesis, and phenotypic markers for increased risk of melanoma in adolescence and adulthood. Special considerations for Spitz nevi and nevi located in particular sites (eg, scalp, acral, genital) are highlighted. Current understanding of the risks associated with congenital melanocytic nevi of different sizes and strategies for the management of children with numerous acquired nevi, Spitz nevi, and congenital nevi are also discussed.

Rare presentations of primary melanoma and special populations: a systematic review

A subset of patients with melanoma present in rare and unique clinical circumstances requiring specific considerations with respect to diagnostic and therapeutic interventions. Herein, we present our review of patients with: (1) primary mucosal melanoma of the head and neck, gastrointestinal, and genitourinary tracts; (2) primary melanoma of the eye; (3) desmoplastic melanoma; (4) subungual melanoma; (5) melanoma in special populations: children, nonwhites, as well as a discussion of familial melanoma.

Atypical Spitz tumors in patients younger than 18 years

BACKGROUND

Diagnosis and proper management of atypical Spitz tumors in pediatric age are still controversial.

OBJECTIVE

We sought to investigate the clinicopathological and molecular features of atypical Spitz tumors in patients aged 18 years or younger.

METHODS

We performed a retrospective clinicopathological and fluorescence in situ hybridization study on 50 pediatric atypical Spitz tumors.

RESULTS

Parameters that were significantly correlated with a diagnosis of atypical Spitz tumors over Spitz nevus included asymmetry, level IV/V, lack of maturation, solid growth, nuclear pleomorphism, high nuclear-cytoplasmic ratio, atypical and deep mitoses, and more than 6 mitoses/mm(2). In the atypical Spitz tumors group, a significantly higher mitotic rate was observed in prepuberal age (P = .04). The 4-probe fluorescence in situ hybridization melanoma assay did not discriminate atypical Spitz tumors from Spitz nevi. Heterozygous 9p21 loss was found in 3 of 37 cases and homozygous 9p21 loss in 2 of 37 cases. Only 1 child experienced a fatal outcome, showing genetic abnormalities by melanoma fluorescence in situ hybridization probe and a heterozygous 9p21 deletion.

LIMITATIONS

The limited number of adverse outcomes did not allow the prognostic analysis of single morphologic features.

CONCLUSION

Pediatric atypical Spitz tumors are associated with minimal lethal potential. Atypical Spitz tumors require complete excision and careful follow-up while our data do not support any clinical benefit for the sentinel lymph node biopsy procedure and completion lymphadenectomy.

Atypical Spitzoid neoplasms: a review of potential markers of biological behavior including sentinel node biopsy

Atypical cutaneous melanocytic lesions, including those with Spitzoid features, can be difficult to categorize as benign or malignant. This can lead to suboptimal management, with potential adverse patient outcomes. Recent studies have enhanced knowledge of the molecular and genetic biology of these lesions and, combined with clinicopathological findings, is further defining their biological spectrum, classification, and behavior. Sentinel node biopsy provides important prognostic information in patients with cutaneous melanoma, but its role in the management of melanocytic lesions of uncertain malignant potential (MELTUMP) is controversial. This paper examines the role of molecular testing and sentinel node biopsy in MELTUMPs, particularly atypical Spitzoid tumors.

p16 Expression Is Lost in Severely Atypical Cellular Blue Nevi and Melanoma Compared to Conventional, Mildly, and Moderately Atypical Cellular Blue Nevi

Background. Significant decreases in p16 expression have been shown to occur in melanoma compared to Spitz tumors, and loss of p16 staining has been found to correlate with melanoma tumor progression. However, comparison of p16 between atypical cellular blue nevi (CBN) and melanoma has not been reported previously. Methods. p16 immunohistochemical staining was evaluated in 14 atypical CBN, 8 conventional and atypical melanocytic nevi, and 16 melanomas, including 4 malignant CBN. p16 staining intensity was graded on a scale of 0–3 and the percentage of melanocytes stained with p16 was determined. Results. p16 staining was significantly higher in all CBN as a group when compared to melanomas (P = 0.001) and malignant CBN (P = 0.00008). Higher p16 expression was also seen in mildly (P = 0.0002) and moderately atypical (P = 0.02), but not severely atypical, CBN compared to melanomas. Conclusions. p16 immunohistochemical expression is higher in mildly and moderately atypical CBN compared to severely atypical CBN and melanomas. In conjunction with additional markers and histology, p16 staining may be useful in confirming the benign nature of these tumors, but is not useful in distinguishing severely atypical CBN from malignant cases, consistent with the overlapping histologic features between these tumors.

Controversies in the evaluation and management of atypical melanocytic proliferations in children, adolescents, and young adults

The rising incidence of melanoma in children has brought increased attention to the clinical and pathologic diagnosis of pigmented lesions in the pediatric age group. Although melanoma in infancy and early childhood is often associated with large congenital nevi, in older children and teenagers it is most often sporadic, occurring in patients with a low skin phototype and substantial sun exposure. The rarity of this potentially fatal disorder demands astute clinical attention and a high index of suspicion for atypical lesions in pediatric patients. The challenges include the difficult decision of whether to biopsy and an often equivocal pathologic diagnosis. These diagnostically challenging and equivocal lesions lead to a degree of uncertainty regarding additional workup, prognosis, potential therapy, and follow-up plans. Consultation with a specialty dermatopathologist can be very helpful, and advanced molecular diagnostic techniques may be used in selected circumstances. Although still controversial, good evidence exists to justify a role for sentinel lymph node biopsy. Patients with atypical melanocytic proliferations have a high rate of positive sentinel lymph nodes; however, their outcomes are clearly better than in similarly staged adults with conventional melanoma. With the multiple variables involved and the relative lack of prospectively derived evidence, clinical decision-making is challenging and patients and families may experience considerable stress. This article provides data and weighs the pros and cons of a rationale for decision-making in pediatric and young adult patients with diagnostically challenging melanocytic lesions.

Molecular pathology of melanocytic tumors

Genetic and genomic analyses of melanocytic tumors have yielded new opportunities for improvements in diagnostic accuracy for the distinction of nevus from melanoma and better selection of patients affected by melanoma for targeted treatment. Since chromosomal copy number changes are commonly found in malignant melanoma, but rare in melanocytic nevi, cytogenetic assays have emerged as a promising ancillary study for the workup of melanocytic tumors with ambiguous light microscopic features. Comparative genomic hybridization (CGH) permits assessment of the full set of chromosomes, but requires a significant amount of lesional tissue, and may fail to detect aberrations in a minor subpopulation of tumor cells. Fluorescence in situ hybridization (FISH) is the cytogenetic assay of choice for limited amounts of tissue. FISH targets only specific chromosomes, with inherent limitations in test sensitivity and specificity. FISH analysis is also heavily dependent on individual experience. Molecular studies have identified distinct sets of mutations in melanoma and/or nevi. These mutations have become clinically relevant for targeted therapy of patients with advanced disease, especially for the treatment of patients with metastatic melanoma carrying the BRAF(V600) or KIT mutations. However, mutation analysis can on occasion also be used for diagnostic purposes.

Sentinel lymph node metastasis is not predictive of poor outcome in patients with problematic spitzoid melanocytic tumors

The diagnosis and clinical management of spitzoid melanocytic tumors with atypical features remain problematic and controversial. In the past decade, sentinel lymph node mapping has been advocated as a diagnostic test in this setting to discriminate melanoma from benign tumors. Recent studies, however, consistently show that despite the presence of lymph node metastases these patients almost always fare well. We investigated the outcome of patients with atypical Spitz tumors and spitzoid melanoma who received sentinel lymph node mapping to clarify current recommendations in managing patients with these diagnostically challenging tumors. A search of the electronic files of the Massachusetts General Hospital Pathology Service identified 41 patients treated with sentinel lymph node biopsy for atypical Spitz tumor or spitzoid melanoma from 1998 to 2008. These patients included 23 patients with atypical Spitz tumors and 17 patients with spitzoid melanoma. Sentinel lymph nodes were positive in 26% of patients with atypical Spitz tumors (6/23) and 35% with spitzoid melanomas (6/17). One patient with spitzoid melanoma developed in-transit metastasis; 0 of 40 patients developed metastases beyond the regional lymph node basin with a mean follow-up of 57 months. Sentinel lymph node biopsy may not be a reliable prognostic discriminatory test in patients with atypical Spitz tumors. Patients with spitzoid melanomas and positive sentinel lymph nodes have a more indolent course than those with bona fide conventional melanoma and positive sentinel nodes.

Cytogenetic and mutational analyses of melanocytic tumors

Analyses of genetic and genomic alterations of melanocytic tumors have not only led to a better understanding of the pathogenesis of melanocytic tumors but also created new opportunities for improvements in diagnostic accuracy in distinguishing nevus from melanoma, and more effective treatments for patients affected by melanoma. Cytogenetic tests have emerged as a promising ancillary method for the workup of diagnostically problematic melanocytic tumors with ambiguous light microscopic features. Mutation analysis not only is important in treatment decision making but also can be used for improved diagnostic accuracy, staging, and prognosis.

Outcomes in pediatric atypical spitz tumors treated without sentinel lymph node biopsy

The diagnosis of atypical Spitz tumor (AST) in a pediatric patient conveys an uncertain potential for malignancy. Although pediatric melanoma is rare, AST may be treated aggressively with sentinel lymph node biopsy (SLNB) and subsequent completion lymphadenectomy. These procedures have unclear therapeutic benefit and potential morbidity. We aimed to collect outcomes on children with AST treated with excision alone to assist in the management of these lesions. We queried our institution's pathology database for AST specimens submitted between 1994 and 2009. A dermatopathologist reviewed pathology slides to confirm AST diagnosis. Clinical information was obtained from medical records, and outcomes surveys were administered to children with AST. Twenty-nine patients met AST diagnostic criteria and were included in this study. Mean age at first excision was 9.0 ± 4.2 (range 2.3-17.5), and 19 patients underwent more than one excision procedure to achieve clear margins. No patient had SLNB. Fourteen patients (48%) with mean follow-up time of 8.4 years (range 3.5-15.8) completed clinical outcomes surveys. Outcomes with mean follow-up time of 2.8 years (range 0.02-8.1 years) were obtained for 10 additional patients from medical records. There were no reports of recurrence, additional lesions, or metastases in these 24 patients. We report one of the largest series of children with AST treated using excision alone and who remain disease free after a significant follow-up period. Our data suggest that SLNB is not warranted in the routine management of pediatric AST. We recommend complete excision with clear margins and careful clinical follow-up.

[Clinical features of Spitz naevus in children: a retrospective study of 196 cases]

AIMS

To better define the characteristics of Spitz naevus (SN) in children, to determine whether it was clinically diagnosed and to examine the differential diagnoses made according to age. In addition, to determine whether atypical spitzoid tumors (AST) have a different presentation from other forms of SN.

PATIENTS AND METHODS

A two-centre retrospective survey was made of histopathological reports written over a 4-year period in children aged under 18 years. The inclusion criterion was unequivocal diagnosis of SN or AST. Age, gender, site, size, course, excision methods, presumptive clinical diagnoses and the percentage of correct diagnosis were analyzed for four distinct age groups.

RESULTS

One hundred and ninety-six patients were included, 186 with SN and 10 with AST. Mean age at diagnosis of SN was 9 years. Female predominance and predilection for the lower limbs were seen for all age groups. Facial involvement was less frequent and chiefly affected children aged under 11 years. Most SN lesions measured between 4 and 8mm. They were often confused with either pyogenic granuloma or juvenile xanthogranuloma, mainly before the age of 11 years. An accurate diagnosis was made in 29% of cases, chiefly in the 0 to 5 year-old age group. No cases of AST were clinically recognized, but it was diagnosed occasionally on histological grounds for very small tumours and in very young children.

CONCLUSION

Clinical diagnosis of SN is not always straightforward and in this study, AST exhibited no special features allowing it to be distinguished from SN. These results underline the need for caution in the event of SN in children, regardless of age or lesion size.

Sentinel node biopsy in atypical melanocytic neoplasms in childhood: a single institution experience in 24 patients

INTRODUCTION

Sentinel lymph node biopsy (SLNB) is a controversial but frequently used adjunct to wide excision of difficult-to-diagnose melanocytic proliferations of childhood. We herein report our institutional experience with SLNB in pediatric patients with these lesions, hereafter referred to as 'atypical melanocytic proliferations'.

METHODS

Our prospectively collected melanoma database was queried for patients ≤21 years of age status post-SLNB for a diagnosis of atypical melanocytic proliferation in which the diagnosis of melanoma ≥1 mm in depth was considered in the differential diagnosis by one or more expert dermatopathologists and for which no diagnostic consensus could be reached.

RESULTS

Of 24 patients identified over 17 years, 7 patients (29%) had a positive sentinel lymph node (SLN). Six SLN-positive patients underwent complete lymph node dissection, with one (14%) having additional nodal involvement identified. With a median follow-up of 4.1 years (range < 0.1 to 14.8 years), all patients showed no evidence of disease.

CONCLUSIONS

Despite a significant rate of identification of melanocytes in SLNs of children with atypical melanocytic proliferations, survival appears favorable and controversy surrounding the significance of nodal involvement remains. Further studies with larger numbers of patients and long-term follow-up are needed before the true prognostic value of SLNB in this setting can be determined.