Spitzoid melanoma in children: clinicopathological study and application of immunohistochemistry as an adjunct diagnostic tool

Regional lymph node evaluation in pediatric conventional melanoma subtype: a single-center 10-year review

PURPOSE

To assess the prognostic and therapeutic significance of sentinel lymph node biopsy (SLNB) and completion lymph node dissection (CLND) in pediatric conventional melanoma (CM), while evaluating potential predictive factors for outcomes.

METHODS

We conducted a retrospective analysis of medical records spanning 2009-2020, focusing on patients aged 18 or younger with localized cutaneous conventional melanoma.

RESULTS

Among the 33 patients, SLNB detected metastasis in 57.6% of cases, with 52.6% undergoing CLND. Positive SLN patients had higher relapse risk (HR 5.92; 95% CI 1.27-27.7; P = 0.024) but similar overall survival (HR 3.19; 95% CI 0.31-33.1, P = 0.33). No significant differences in disease-free survival (DFS) and OS were found between patients who underwent CLND and those who did not (HR 1.91; 95% CI 0.49-7.43, P = 0.35, and HR 0.52; 95% CI 0.03-8.32, P = 0.64, respectively). Univariate analysis showed age at diagnosis (P = 0.02) correlated with higher recurrence risk, with a 21% hazard increase per additional year of age.

CONCLUSIONS

Positive SLN status and age at diagnosis were associated with worse DFS in CM patients. Our study did not find any prognostic or therapeutic value in CLND for pediatric melanoma. Further multicenter trials are needed to confirm our single-institution experience.

LEVEL OF EVIDENCE

Level IV.

Pediatric Atypical Melanocytic Proliferations: Single-Site Retrospective Cohort Assessment of Treatment and Long-Term Follow-Up

Atypical and malignant cutaneous tumors are understudied in the pediatric population, with limited data on long-term follow-up. This study examines pediatric (0-18 years) atypical melanocytic proliferations over a twenty-year period (January 2002-December2022) using the EPIC SlicerDicer at our institution. Over a twenty-year period, there were 55 cases of pediatric melanoma (53 patients). The median follow-up time was 8 years, 11 months. A proportion of 96% were treated with wide local excision (WLE), and 47% had a sentinel lymph node biopsy (SLNB) (35% positive rate). There were 101 atypical Spitz tumor cases (85% atypical Spitz tumors, 15% Spitz melanoma), with a median follow-up duration of 9 years. A proportion of 77% were treated with WLE (with one patient dying of metastatic disease). There were 10 cases of atypical melanocytic proliferations not otherwise specified, including 5 pigmented epithelioid melanocytomas (PEM), 4 deep-penetrating nevi, and 1 atypical cellular blue nevus. This study adds to the growing body of knowledge on pediatric atypical cutaneous melanocytic proliferations, aligning with many described characteristics such as disease location and overall survival rates, with distinct exceptions (higher melanoma positive SLNB rate, lower atypical Spitz tumor WLE rate, and a case of fatal metastatic atypical Spitz tumor).

Combined utility of p16 and BRAF V600E in the evaluation of spitzoid tumors: Superiority to PRAME and correlation with FISH

BACKGROUND

Spitzoid melanocytic neoplasms are diagnostically challenging; criteria for malignancy continue to evolve. The ability to predict chromosomal abnormalities with immunohistochemistry (IHC) could help select cases requiring chromosomal evaluation.

METHODS

Fluorescence in situ hybridization (FISH)-tested spitzoid neoplasms at our institution (2013-2021) were reviewed. p16, BRAF V600E, and preferentially expressed antigen in melanoma (PRAME) IHC results were correlated with FISH.

RESULTS

A total of 174 cases (1.9F:1M, median age 28 years; range, 5 months-74 years) were included; final diagnoses: Spitz nevus (11%), atypical Spitz tumor (47%), spitzoid dysplastic nevus (9%), and spitzoid melanoma (32%). Sixty (34%) were FISH positive, most commonly with absolute 6p25 gain (RREB1 > 2). Dermal mitotic count was the only clinicopathologic predictor of FISH. Among IHC-stained cases, p16 was lost in 55 of 134 cases (41%); loss correlated with FISH positive (p < 0.001, Fisher exact test). BRAF V600E (14/88, 16%) and PRAME (15/56, 27%) expression did not correlate with FISH alone (p = 0.242 and p = 0.359, respectively, Fisher exact test). When examined together, however, p16-retained/BRAF V600E-negative lesions had low FISH-positive rates (5/37, 14%; 4/37, 11% not counting isolated MYB loss); all other marker combinations had high rates (56%-75% of cases; p < 0.001).

CONCLUSIONS

p16/BRAF V600E IHC predicts FISH results. "Low-risk" lesions (p16⁺ /BRAF V600E^- ) uncommonly have meaningful FISH abnormalities (11%). PRAME may have limited utility in this setting.

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.

Pathologic Characteristics of Spitz Melanoma With MAP3K8 Fusion or Truncation in a Pediatric Cohort

Spitz melanoma is a rare variant of melanoma defined by distinct clinical, histologic, and genetic features and affecting patients of all ages. Half of these tumors are driven by fusion of kinase genes including ALK, NTRK1/3, ROS1, RET, MET, or BRAF. We recently reported recurrent fusion or truncation of the potentially targetable serine-threonine kinase gene MAP3K8 in 33% of Spitz melanomas. Here we describe the histologic features of these MAP3K8-rearranged tumors (16 pediatric Spitz melanomas; 1 atypical Spitz tumor), using hematoxylin-eosin slides, p16 immunohistochemistry, and CDKN2A fluorescence in situ hybridization. The lesions consisted of a compound melanocytic proliferation, ranging in thickness from 1.5 to 13.4 mm (median, 3.1 mm), with 8 having a predominant dermal and 3 having a predominant junctional component. The predominant cell type was epithelioid (94%). The epithelioid melanocytes were generally monomorphic and amelanotic, arranged in expansile epithelial aggregates, confluent hypercellular nests, or enlarged syncytial nodules in the dermis. Ulceration was present in 9 of 17 tumors (53%) and deep mitotic figures were seen in 15 of 17 tumors (88%). Complete loss of p16 expression and homozygous CDKN2A deletion were observed in 82% and 70% of tumors, respectively. Recognition of MAP3K8-altered Spitz melanoma may thus be facilitated by these morphologic features, most notably presence of cohesive cellular nodules in the dermis and an epithelioid-cell phenotype.

Immunohistochemical Staining in the Assessment of Melanoma Tumor Thickness

Vertical tumor thickness has great influence in the prognosis and staging of melanoma. The aim of this study was determination of the differences between melanoma tumor thickness in conventional hematoxylin and eosin (H&E) and immunohistochemical techniques. Thirty-six biopsy specimens were included in our study. For each sample, four adjacent tissue sections were stained with H&E, in addition S-100, Melan- A and HMB-45 staining was performed on the next serial sections. The mean thickness of tumor invasion was 2.16, 2.38, 2.22 and 2.29 mm in H&E, S-100, HMB45 and Melan-A sections evaluation, respectively. The mean difference of the Breslow thickness between H&E and S-100 and also, between H&E and Melan-A stained slides were statistically significant (p˂0.05) while no difference was found in the tumor thickness of the H&E and HMB45 staining evaluation (p = 0.278). Greater tumor thickness was observed in 25 lesions (69.4%) with S-100, 20 lesions (55.5%) with Melan-A and 17 (47.2%) lesions in HMB-45 rather than H&E staining. Conclusively, it appears that H&E staining cannot prove the actual size of melanoma invasion in some cases and immunohistochemical examination can be a complementary method in this situations. Of the melanoma associated immunomarkers, the combination of S-100 and Melan-A staining may suffice to measure depth of tumor invasion.

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.

Pathological review of primary cutaneous malignant melanoma by a specialist skin cancer multidisciplinary team improves patient care in the UK

AIMS

The National Institute for Health and Care Excellence advocated the development of specialist skin cancer multidisciplinary teams (SSMDTs) for the management of higher risk invasive skin cancers in the UK. The interobserver variability in the histopathological assessment of primary cutaneous malignant melanoma (PCMM) is well recognised.

METHODS

We evaluated the discordance rates in the assessment of the histopathological criteria of PCMM based on the eighth American Joint Committee on Cancer (AJCC) melanoma staging system and subsequent change in prognosis and management following pathology review by an SSMDT.

RESULTS

353 cases of PCMM were referred to our SSMDT between April 2015 and May 2016. Cases in which there was a discrepancy in one or more histological parameters following expert review were collected retrospectively. Of 341 eligible cases, there were 94 (27.6%) in which there was an alteration in any parameter. There was interobserver agreement in final diagnosis in 96.8%, Breslow thickness in 86.8%, ulceration in 98.2%, microsatellites in 98.5%, tumour mitotic rate in 88.9%, histological subtype in 92.4%, growth phase in 98.5%, angiolymphatic invasion in 97.7%, perineural invasion in 98.8%, regression in 95.3% and tumour-infiltrating lymphocytes in 95.0%. A corresponding change in AJCC stage occurred in 23 cases (6.7%), with a resulting change in clinical management in 10 cases (2.9%).

CONCLUSIONS

Disagreements in the pathological assessment of PCMM can have significant clinical implications for a small number of patients. Our findings highlight the value of the SSMDT for high-quality care of patients with melanoma in the UK.

Medical Options for the Adjuvant Treatment and Management of Pediatric Melanoma

Although melanoma is a rare diagnosis in the pediatric population, advances in the management of adults with melanoma offer the prospect of promising therapeutic options for children. At this time, medical management is not considered curative but may reduce the risk of recurrence or prolong survival. Surgical management remains the mainstay of treatment. Medical therapy of pediatric melanoma is not thought to have a role for in situ, early-stage, or localized disease, but adjuvant therapy may have a role in improving the prognosis of patients with positive sentinel lymph node biopsy (SLNB), spread beyond the regional lymph node basin, metastatic disease, or recurrent disease. Medical treatment options include immunotherapies, particularly checkpoint inhibitors, and targeted therapies, which have provided improved toxicity profiles compared with traditional chemotherapy regimens in the setting of advanced disease. There is a growing body of pediatric-specific data relevant to the use of adjuvant therapies for advanced melanoma in children.

Expression of p15 in a spectrum of spitzoid melanocytic neoplasms

BACKGROUND

Accurate classification of spitzoid melanocytic lesions is difficult due to overlapping clinical and histopathologic features between Spitz nevi, atypical Spitz tumors (ASTs), and spitzoid melanomas. Expression of p16 (CDKN2A) has been used as a marker of spitzoid lesions. However, its expression may be variable. p15 is a tumor suppressor encoded by CDKN2B, loss of which has been recently shown to promote transition from nevus to melanoma. We sought to determine whether p15 is a useful immunohistochemical marker to distinguish Spitz nevi from spitzoid melanomas and to compare p15 and p16 staining in this population.

METHODS

Immunohistochemistry for p15 and p16 was performed on Spitz nevi (n = 19), ASTs (n = 41), and spitzoid melanomas (n = 17). Immunoexpression was categorized by a four-tiered system: 0 (negative), 1+ (weak), 2+ (moderate), 3+ (strong).

RESULTS

3+/strong p15 staining was observed in 68.4% of Spitz nevi, 34.2% of ASTs, and 17.7% of spitzoid melanomas. By contrast, we observed 3+ p16 staining in roughly equivalent percentages of Spitz nevi (57.9%), ASTs (56.1%), and spitzoid melanomas (58.8%).

CONCLUSION

These data illustrate that p15 may be more useful than p16 as a biomarker to help distinguish benign from malignant spitzoid lesions.

A Practical Approach to the Diagnosis of Melanocytic Lesions

CONTEXT.—

Melanocytic lesions are common in routine surgical pathology. Although the majority of these lesions can be confidently diagnosed using well-established morphologic criteria, there is a significant subset of lesions that can be diagnostically difficult. These can be a source of anxiety for patients, clinicians, and pathologists, and the potential consequences of a missed diagnosis of melanoma are serious.

OBJECTIVE.—

To provide a practical approach to the diagnosis of melanocytic lesions, including classic problem areas as well as suggestions for common challenges and appropriate incorporation of ancillary molecular techniques.

DATA SOURCES.—

Literature search using PubMed and Google Scholar, incorporating numerous search terms relevant to the particular section, combined with contemporaneous texts and lessons from personal experience.

CONCLUSIONS.—

Although a subset of melanocytic lesions can be diagnostically challenging, the combination of a methodical approach to histologic assessment, knowledge of potential diagnostic pitfalls, opinions from trusted colleagues, and judicious use of ancillary techniques can help the pathologist navigate this difficult area.

Pathology and genomics of pediatric melanoma: A critical reexamination and new insights

The clinicopathologic features of pediatric melanoma are distinct from those of the adult counterpart. For example, most childhood melanomas exhibit a uniquely favorable biologic behavior, save for those arising in large/giant congenital nevi. Recent studies suggest that the characteristically favorable biologic behavior of childhood melanoma may be related to extreme telomere shortening and dysfunction in the cancer cells. Herein, we review the genomic profiles that have been defined for the different subtypes of pediatric melanoma and particularly emphasize the potential prognostic value of telomerase reverse transcriptase alterations for these tumors.

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.

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.

Spitz Nevi and Other Spitzoid Neoplasms in Children: Overview of Incidence Data and Diagnostic Criteria

Spitz nevi are benign melanocytic neoplasms characterized by epithelioid or spindle melanocytes or both. In some rare cases their presentation overlaps with the clinical and histopathologic features of malignant melanoma, so a differential diagnosis can be difficult to make. Intermediate forms between Spitz nevi and malignant melanoma, with unpredictable behavior, have been called atypical Spitz tumors. A literature search was performed to review the clinical, dermoscopic, genetic, and histopathologic aspects of spitzoid tumors. Spitz nevi mainly occur in children, with no predilection for sex, and in young women. Common sites are the head and lower arms, where Spitz nevi present as pink nodules or hyperpigmented plaques. Spitzoid lesions may have diverse dermoscopic patterns: vascular, starburst, globular, atypical, reticular, negative homogeneous, or targetoid. The management of spitzoid lesions can be invasive or conservative; surgical excision is usually reserved for those with doubtful features, whereas clinical and dermoscopic follow-up is preferred for typical pediatric Spitz nevi. The role of sentinel lymph node biopsy in atypical Spitz tumors is debated. Immunohistochemistry and new molecular techniques such as comparative genomic hybridization, polymerase chain reaction, and fluorescence in situ hybridization offer new diagnostic perspectives, investigating genetic alterations that are specific for malignant melanoma or for Spitz nevi.

A diagnostic algorithm for atypical spitzoid tumors: guidelines for immunohistochemical and molecular assessment

Atypical spitzoid tumors are a morphologically diverse group of rare melanocytic lesions most frequently seen in children and young adults. As atypical spitzoid tumors bear striking resemblance to Spitz nevus and spitzoid melanomas clinically and histopathologically, it is crucial to determine its malignant potential and predict its clinical behavior. To date, many researchers have attempted to differentiate atypical spitzoid tumors from unequivocal melanomas based on morphological, immonohistochemical, and molecular diagnostic differences. A diagnostic algorithm is proposed here to assess the malignant potential of atypical spitzoid tumors by using a combination of immunohistochemical and cytogenetic/molecular tests. Together with classical morphological evaluation, this algorithm includes a set of immunohistochemistry assays (p16(Ink4a), a dual-color Ki67/MART-1, and HMB45), fluorescence in situ hybridization (FISH) with five probes (6p25, 8q24, 11q13, CEN9, and 9p21), and an array-based comparative genomic hybridization. This review discusses details of the algorithm, the rationale of each test used in the algorithm, and utility of this algorithm in routine dermatopathology practice. This algorithmic approach will provide a comprehensive diagnostic tool that complements conventional histological criteria and will significantly contribute to improve the diagnosis and prediction of the clinical behavior of atypical spitzoid tumors.

Time to reconsider Spitzoid neoplasms?

Background:

Spitzoid neoplasms may pose significant diagnostic problems because in a fraction of them it is quite difficult or impossible to establish if they are benign or malignant lesions. An extraordinarily large number of studies have been made in attempts to solve this problem; regrettably, the histological criteria proposed and the various special sophisticated techniques employed have proven to be ineffective in making this distinction with confidence.

Objectives:

To explore the possible causes for this diagnostic failure and an attempt to identify the source of this problem.

Method:

A historical and technical analysis of the specialized literature is performed, critically evaluating the main points of this controversial topic.

Results:

The reasons for the diagnostic failure in Spitzoid neoplasms are not clear but could be the result of inappropriate conceptual representation. The analysis of available data and a rational review of old and new assumptions and concepts may suggest a different representation for Spitzoid neoplasms: Spitz nevus, atypical Spitz tumor and Spitzoid melanoma, rather than being three different tumors that are difficult or impossible to distinguish with assurance, could be viewed as one unique entity, Spitz tumor (ST). This tumor is a low-grade malignant neoplasm, in which the amount of intrinsic risk is variable, ranging from very low to high (ST1, ST2, ST3), and malignant potential could be estimated.

Conclusions:

The proposed alternative representation of Spitzoid neoplasms as a unique tumor may help in overcoming the difficulty in diagnosis of these tumors.

The landscape of fusion transcripts in spitzoid melanoma and biologically indeterminate spitzoid tumors by RNA sequencing

Kinase activation by chromosomal translocations is a common mechanism that drives tumorigenesis in spitzoid neoplasms. To explore the landscape of fusion transcripts in these tumors, we performed whole-transcriptome sequencing using formalin-fixed, paraffin-embedded (FFPE) tissues in malignant or biologically indeterminate spitzoid tumors from 7 patients (age 2-14 years). RNA sequence libraries enriched for coding regions were prepared and the sequencing was analyzed by a novel assembly-based algorithm designed for detecting complex fusions. In addition, tumor samples were screened for hotspot TERT promoter mutations, and telomerase expression was assessed by TERT mRNA in situ hybridization (ISH). Two patients had widespread metastasis and subsequently died of disease, and 5 patients had a benign clinical course on limited follow-up (mean: 30 months). RNA sequencing and TERT mRNA ISH were successful in six tumors and unsuccessful in one disseminating tumor because of low RNA quality. RNA sequencing identified a kinase fusion in five of the six sequenced tumors: TPM3-NTRK1 (2 tumors), complex rearrangements involving TPM3, ALK, and IL6R (1 tumor), BAIAP2L1-BRAF (1 tumor), and EML4-BRAF (1 disseminating tumor). All predicted chimeric transcripts were expressed at high levels and contained the intact kinase domain. In addition, two tumors each contained a second fusion gene, ARID1B-SNX9 or PTPRZ1-NFAM1. The detected chimeric genes were validated by home-brew break-apart or fusion fluorescence in situ hybridization (FISH). The two disseminating tumors each harbored the TERT promoter -124C>T (Chr 5:1,295,228 hg19 coordinate) mutation, whereas the remaining five tumors retained the wild-type gene. The presence of the -124C>T mutation correlated with telomerase expression by TERT mRNA ISH. In summary, we demonstrated complex fusion transcripts and novel partner genes for BRAF by RNA sequencing of FFPE samples. The diversity of gene fusions demonstrated by RNA sequencing defines the molecular heterogeneity of spitzoid neoplasms.

Single institution experience of paediatric melanoma in Victoria, Australia

BACKGROUND/OBJECTIVES

Paediatric melanoma is an uncommon presentation of melanoma that accounts for 3% of all paediatric cancers. The objective was to describe a series of paediatric melanoma cases presenting to a state-wide tertiary referral service over the past 19 years.

METHODS

A search of the Victorian Melanoma Service database was performed to identify all patients under the age of 20 years diagnosed with melanoma from 1994 to 2013. Histological, demographic and phenotypical information for each patient was collected. Patients were matched against the Victorian Death Registry to identify those who had died. Fisher's exact test was used to examine associations. Melanoma-specific survival was estimated using the Kaplan-Meier method.

RESULTS

A total of 65 paediatric melanoma patients were included for analysis, in whom 72.3% of melanomas were diagnosed when they were 16-19 years of age with a mean age at diagnosis of 16 years. The mean Breslow thickness was 1.4 mm. It was greatest (3.4 mm) in the youngest age group (< 12 years of age). Ten patients developed nodal metastatic disease, eight of which progressed to visceral metastatic disease. The 5-year melanoma-specific survival rate was 96.8%.

CONCLUSION

This is the first descriptive epidemiological study of paediatric melanoma in Victoria. Further large, population-based, multi-institutional studies of paediatric melanoma are warranted to provide a clearer understanding of this group of melanoma patients.

Atypical Spitz Tumors: A Diagnostic Challenge

Spitzoid melanocytic lesions encompass a spectrum from benign Spitz nevi to malignant spitzoid melanomas. Spitzoid melanocytic neoplasms have significant morphologic and molecular differences from conventional melanocytic lesions, and prediction of biologic behavior and metastatic risk may be difficult. Most challenging is the atypical Spitz tumor, a borderline spitzoid melanocytic lesion of uncertain malignant potential that has overlapping histologic features with conventional Spitz nevus and spitzoid melanoma. Atypical Spitz tumors involve the sentinel lymph nodes at a greater frequency than conventional melanoma and frequently harbor chromosomal copy number changes, yet most cases follow an indolent course. Herein we review the clinical, microscopic, and molecular features of atypical Spitz tumors, including recent molecular advances, including the potential prognostic significance of chromosomal abnormalities, such as homozygous CDKN2A loss.

A p16-Ki-67-HMB45 immunohistochemistry scoring system as an ancillary diagnostic tool in the diagnosis of melanoma

BACKGROUND

Melanoma is a skin cancer which treatment requires early diagnosis and large surgical removal. The histopathological diagnosis of a melanocytic tumour is sometimes difficult between a benign nevus and a malignant melanoma. We built an immunomarker-based score to differentiate nevi from melanomas.

METHODS

Two independent sets of 308 (first set) and 62 (validation set) formalin-fixed and paraffin embedded tumour samples were studied using p16-Ki-67 and HMB45-MelanA dual-staining immunohistochemistry.

RESULTS

In the first set of tumours, high Ki-67 index, low to null p16 immunohistochemistry and absence of HMB45 immunohistochemistry gradient were more frequent in melanomas (156 primary tumours and 78 metastases) than in nevi (74 tumours). Nevertheless, none of these single parameters was able to differentiate all primary melanomas from all nevi. We built a scoring system based on the addition of semi-quantitative scorings of Ki-67 (0: <2%; 1:2-5%; 2:6-10%, 3:11-20%; 4:>20%) and p16 (0:>50% stained cells; 1:11-50%; 2:1-10%; 3:0%) and HMB45 staining (0: gradient present; 1: doubtful/inconclusive gradient; 2: gradient absent). A p16-Ki-67-HMB45 total score from 0 to 9 permitted to classify nevi (score <4) and primary melanomas (score ≥4) with a sensitivity of 97.4% and a specificity of 97.3% in the first set of tumours. Sensibility and specificity of 100 % were obtained in a second set (validation set) of 62 tumours (46 melanomas and 16 nevi). The total scoring also allowed analyzing 11 difficult or initially misdiagnosed tumours in our files.

CONCLUSIONS

We propose a valuable triple p16-Ki-67-HMB45 immunohistochemistry scoring system to help pathologists in the differential diagnosis of melanomas and nevi.

TERT Promoter Mutations Are Predictive of Aggressive Clinical Behavior in Patients with Spitzoid Melanocytic Neoplasms

Spitzoid neoplasms constitute a morphologically distinct category of melanocytic tumors, encompassing Spitz nevus (benign), atypical Spitz tumor (intermediate malignant potential), and spitzoid melanoma (fully malignant). Currently, no reliable histopathological criteria or molecular marker is known to distinguish borderline from overtly malignant neoplasms. Because TERT promoter (TERT-p) mutations are common in inherently aggressive cutaneous conventional melanoma, we sought to evaluate their prognostic significance in spitzoid neoplasms. We analyzed tumors labeled as atypical Spitz tumor or spitzoid melanoma from 56 patients with available follow-up data for the association of TERT-p mutations, biallelic CDKN2A deletion, biallelic PTEN deletion, kinase fusions, BRAF/NRAS mutations, nodal status, and histopathological parameters with risk of hematogenous metastasis. Four patients died of disseminated disease and 52 patients were alive and disease free without extranodal metastasis (median follow-up, 32.5 months). We found TERT-p mutations in samples from the 4 patients who developed hematogenous metastasis but in none of tumors from patients who had favorable outcomes. Presence of TERT-p mutations was the most significant predictor of haematogenous dissemination (P < 0.0001) among variables analyzed. We conclude that TERT-p mutations identify a clinically high-risk subset of patients with spitzoid tumors. Application of TERT-p mutational assays for risk stratification in the clinic requires large-scale validation.

Clinical characteristics associated with Spitz nevi and Spitzoid malignant melanomas: the Yale University Spitzoid Neoplasm Repository experience, 1991 to 2008

BACKGROUND

Spitz nevi and Spitzoid malignant melanomas are uncommon and may be difficult to distinguish histopathologically. Identification of clinical features associated with these lesions may aid in diagnosis.

OBJECTIVE

We sought to identify clinical characteristics associated with Spitz nevi and Spitzoid malignant melanomas.

METHODS

We conducted a retrospective cohort study of Spitz nevi and Spitzoid malignant melanomas from the Yale University Spitzoid Neoplasm Repository diagnosed from years 1991 through 2008. Descriptive statistics and multivariate logistic regression were used to compare select patient- and tumor-level factors associated with each lesion.

RESULTS

Our cohort included 484 Spitz nevi and 54 Spitzoid malignant melanomas. Spitz nevi were more common (P = .03) in females (65%; n = 316) compared with Spitzoid malignant melanomas (50%; n = 27), occurred more frequently in younger patients (mean age at diagnosis 22 vs 55 years; P < .001), and more likely presented as smaller lesions (diameter 7.6 vs 10.5 mm; P < .001). Increasing age (odds ratio 1.16, 95% CI [1.09, 1.14]; P< .001) and male gender (odds ratio 2.77, 95% CI [1.17, 6.55]; P< .02) predicted Spitzoid malignant melanoma diagnosis.

LIMITATIONS

Small sample size, unmeasured confounding, and restriction to a single institution may limit the accuracy and generalizability of our findings.

CONCLUSIONS

Age and gender help predict diagnosis of Spitz nevi and Spitzoid malignant melanomas.

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.

The genomic landscape of childhood and adolescent melanoma

Despite remarkable advances in the genomic characterization of adult melanoma, the molecular pathogenesis of pediatric melanoma remains largely unknown. We analyzed 15 conventional melanomas (CMs), 3 melanomas arising in congenital nevi (CNMs), and 5 spitzoid melanomas (SMs), using various platforms, including whole genome or exome sequencing, the molecular inversion probe assay, and/or targeted sequencing. CMs demonstrated a high burden of somatic single-nucleotide variations (SNVs), with each case containing a TERT promoter (TERT-p) mutation, 13/15 containing an activating BRAF V600 mutation, and >80% of the identified SNVs consistent with UV damage. In contrast, the three CNMs contained an activating NRAS Q61 mutation and no TERT-p mutations. SMs were characterized by chromosomal rearrangements resulting in activated kinase signaling in 40%, and an absence of TERT-p mutations, except for the one SM that succumbed to hematogenous metastasis. We conclude that pediatric CM has a very similar UV-induced mutational spectrum to that found in the adult counterpart, emphasizing the need to promote sun protection practices in early life and to improve access to therapeutic agents being explored in adults in young patients. In contrast, the pathogenesis of CNM appears to be distinct. TERT-p mutations may identify the rare subset of spitzoid melanocytic lesions prone to disseminate.

Non-pigmented melanoma with nodal metastases masquerading as pyogenic granuloma in a 1-year old

Malignant melanomas are the most common skin cancer in the pediatric population. Melanoma incidence is extremely low in infants, and metastatic disease is even less common. We present the case of an 11-month-old girl who presented with a non-pigmented lesion that progressed to an ulcerated lesion. Pathology was found to be Spitzoid melanoma of 7.6-mm thickness. Micrometastases were found on examination of the sentinel lymph node. The family chose expectant observation following the excision procedure. A pediatric melanoma registry may be helpful in developing future analyses of incidence in survival in this specialized population.

Spitzoid melanoma in a child with Li-Fraumeni syndrome

Spitzoid melanoma of childhood is a rare malignancy. The histological features are at the upper end of a range encompassing Spitz nevus and atypical Spitz tumor, the unifying features including large oval, fusiform or polygonal melanocytes with abundant homogeneous-appearing cytoplasma and large vesicular nuclei. The presence of a "bottom-heavy" pattern, strikingly enlarged nuclei and nucleoli in both the upper and lower portions of the lesion, and deep mitotic figures are among the findings that distinguish most of the Spitzoid melanomas from Spitz nevi and atypical Spitz tumors. There are no syndromic associations reported for this malignancy. We report the occurrence of choroid plexus carcinoma, Spitzoid melanoma, and myelodysplasia in a child who was found to carry a germline mutation for TP53. While choroid plexus carcinoma and myelodysplasia have relatively frequently been described, melanomas have been very rarely described in Li-Fraumeni syndrome. The association of Spitzoid melanoma with Li-Fraumeni syndrome, especially in a pediatric patient, has not been reported before.

Role of lymphoscintigraphy and sentinel lymph node biopsy in the management of pediatric melanoma and sarcoma

PURPOSE

The purpose of this study was to describe the use of lymphoscintigraphy and sentinel lymph-node biopsy (SLNB) for the management of children with melanoma and sarcomas. We report the experience of two children's hospitals that utilize this technique to identify sentinel lymph nodes for lymph-node biopsy and dissection.

METHODS

We identified 56 patients (median age 10.8 years) who underwent 58 lymphoscintigraphy procedures. There were 33 patients with melanoma and melanocytic lesions, and 23 with sarcomas.

RESULTS

Of 58 lymphoscintigraphy procedures, sentinel lymph nodes were identified in 52 (90% success rate). Using the combination of intraoperative blue dye injection and lymphoscintigraphy, the success rate was 95% (55/58). Metastatic disease was found in 14 sentinel lymph nodes (13 patients with melanoma and melanocytic lesions, and 1 patient with rhabdomyosarcoma).

CONCLUSION

We have found that lymphoscintigraphy with SLNB is an effective method to identify patients who may benefit from more extensive lymph-node dissection and to identify those patients who are unlikely to benefit from further lymph-node exploration.

A case of spitzoid melanoma with lymph node metastasis in a child

The distinction of a spitz nevus from a melanoma can be difficult and in some cases, impossible. A misdiagnosed spitz nevus can metastasize and lead to fatal outcomes, especially in children. A 5-yr-old girl presented with a 1-yr history of a solitary pinkish nodule on her left hand. On physical examination, she had a palpable left axillary lymph node. We performed biopsy and checked 3 sentinel lymph nodes (SLN) on her axillary area. The biopsy specimen showed multiple variably sized and shaped nests with large spindle or polygonal cells and SLN biopsy showed 3 of 3 lymph nodes that were metastasized. Under the diagnosis of spitzoid melanoma, she was treated with excision biopsy and complete left axillary lymph nodes were dissected. She received interferon-α2b subcutaneously at a dose of 8 MIU per day, 3 times weekly for 12 months, and shows no recurrence.

Melanoma pathology: important issues for clinicians involved in the multidisciplinary care of melanoma patients

Histologic analysis remains the gold standard for diagnosis of melanoma. The pathology report should document those histologic features important for guiding patient management, including those characteristics on which the diagnosis was based and also prognostic factors. Pathologic examination of sentinel lymph nodes provides very important prognostic information. New techniques, such as comparative genomic hybridization and fluorescence in situ hybridization are currently being studied to determine their usefulness in the diagnosis of melanocytic lesions. Recent molecular studies have opened new avenues for the treatment of patients with metastatic melanoma (ie, targeted therapies) and molecular pathology is likely to play an important role in the emerging area of personalized melanoma therapy.

Nevus/Melanocytoma/Melanoma: an emerging paradigm for classification of melanocytic neoplasms?

CONTEXT

Until recently, the prevailing paradigm in classification and clinical management of melanocytic proliferations mandated dichotomous classification of all melanocytic lesions as either entirely benign (nevus) or entirely malignant (melanoma). However, some diagnostically challenging lesions cannot be unequivocally classified as nevus or melanoma by histologic evaluation of the primary tumor. Such lesions have been referred to as borderline or melanocytic tumors of uncertain malignant potential.

OBJECTIVE

To review and update the problem of diagnostically difficult melanocytic proliferations and recent concepts regarding borderline melanocytic tumors.

DATA SOURCES

Published literature and personal experience of the authors.

CONCLUSIONS

Preliminary evidence indicates that it may be appropriate to expand the classification scheme of melanocytic neoplasms to include a third diagnostic category of melanocytic lesions of intermediate malignant potential that are capable of metastasis to regional lymph nodes but have limited potential for distant spread. We propose the term melanocytoma for this group of lesions. We believe that a nevus/melanocytoma/melanoma paradigm may provide a useful intellectual framework to understand, research, and clinically manage borderline melanocytic tumors.

Melanoma in children

CONTEXT

Cutaneous melanoma in childhood (CMC) is rare; therefore, its prognostic factors and biologic behavior, and the effectiveness of adjuvant techniques for CMC remain mostly unknown.

OBJECTIVE

To review the most useful, evidence-based practice criteria for establishing the diagnosis of CMC, for which universally accepted criteria are lacking, in order to facilitate the interpretation and comparison of the results from different institutions, and to perform systematic reviews and meta-analysis.

DATA SOURCES

A comprehensive review of the most relevant previous single-institution series reported in the literature since 1990, including our cumulative experience of 137 cases of primary cutaneous and mucosal melanoma in patients younger than 18 years. Special characteristics of melanoma in children are discussed, regarding clinical settings and risk factors, helpful histologic features, and immunohistochemical patterns for diagnosis and prognosis.

CONCLUSIONS

Careful analysis of histologic features as well as the additional information provided by immunohistochemistry should allow for a correct diagnosis in most cases of melanoma in children. Although it seems that pediatric patients with melanoma have higher survival probability than adults, still a number of children will develop metastasis and die of their disease, particularly when melanoma is diagnosed after puberty. Until further studies more accurately determine the prognosis, a prudent approach to CMC diagnosis and therapy seems to follow the same principles as those established for adult melanoma.

Cutaneous Spitzoid melanoma in a very young girl of Asian descent

Cutaneous melanoma is extremely uncommon in children. Further, Asian-Americans appear to be at decreased risk for cutaneous melanoma. The authors present the case of a prepubescent Asian girl who presents with the rare spitzoid variant of cutaneous melanoma. The patient is a 4-year-old girl of Chinese descent who presented with a red, raised nodule, which increased in size over a 3-month period. She underwent wide local excision with sentinel lymph node dissection. On histopathologic analysis, she was found to have Spitzoid melanoma of childhood/adolescence. Spitzoid melanoma in children is rare and incompletely understood. A recent systematic review was only able to identify 82 such cases published over a 57-year period. To our knowledge, this is the first report of Spitzoid melanoma in a paediatric age patient of Asian descent. While this clearly is an uncommon demographic, it seeks to highlight important differences in racial predilection for Spitzoid melanoma.

Prognostic factors for melanoma in children and adolescents: a clinicopathologic, single-center study of 137 Patients

BACKGROUND

Cutaneous melanoma in childhood is rare; therefore, its prognostic factors and biologic behavior and the effectiveness of adjuvant diagnostic techniques in this group remain mostly unknown.

METHODS

The authors conducted a retrospective, observational study on the prognostic significance of clinical and pathologic findings from 137 cutaneous and mucosal melanomas in patients aged <18 years that were reviewed by the pathology department of a large cancer center during the period from 1992 to 2006.

RESULTS

Univariate analysis indicated that there was a significantly greater risk of metastases for patients who had previous nonmelanocytic malignancies, nodular histologic type, fusiform or spitzoid cytology, high Breslow thickness, vertical growth phase, high dermal mitotic activity, ulceration, and vascular invasion. Adjacent nevus and radial growth phase were associated with a better prognosis. Twelve patients (10.3%) died during follow-up. Decreased overall survival was related significantly to age >10 years, previous nonmelanocytic malignancy, high Breslow thickness, high Clark level, and the presence of metastases at diagnosis. All patients who died were aged ≥ 11 years, and 8 of those patients had metastases at diagnosis. In multivariate analysis, higher Breslow thickness predicted an increased risk of metastases, whereas age >10 years and the presence of metastases at diagnosis were associated with decreased survival.

CONCLUSIONS

Similar to adults, the detection of metastases at diagnosis in children with melanoma was 1 of the main factors that influenced overall survival. Melanomas that were detected in children aged <11 years appeared to have a less aggressive behavior than those detected in adults.

Spindle cell melanocytic lesions--part I: an approach to compound naevoidal pattern lesions with spindle cell morphology and Spitzoid pattern lesions

Melanocytic lesions show great morphological diversity in their architecture and the cytomorphological appearance of their composite cells. Whereas functional melanocytes reveal a dendritic cytomorphology and territorial isolation, lesional naevomelanocytes and melanoma cells typically show epithelioid, spindled or mixed cytomorphologies and a range of architectural arrangements. Spindling is common to melanocytic lesions, and may be either a characteristic feature or a divergent appearance. The presence of spindle cells may mask the melanocytic nature of a lesion, and is often disconcerting, either because of its infrequent appearance in a particular lesion or its interpretation as a dedifferentiated phenotype. Spindle cell melanocytic lesions follow the full spectrum of potential biological outcomes, and difficulty may be experienced judging the nature of a lesion because of a lack of consistently reliable features to predict biological behaviour. Over time, recognition of numerous histomorphological features that may portend a more aggressive lesion have been identified. However, the translation of these features into a diagnostic entity requires a gestalt approach. Although most spindle cell melanocytic lesions can reliably be resolved with this standard approach, problem areas do exist and cause no end of grief to the surgical pathologist or dermatopathologist. In this review, the authors present their algorithmic approach to spindle cell melanocytic lesions and discuss each entity in turn, in order to (1) model a systematic approach to such lesions, and (2) provide familiarity with those melanocytic lesions that either typically or occasionally display a spindled cytomorphology.