Are all melanomas the same?

Giant lung metastasis of NRAS-mutant melanoma in a 24-year-old patient with a history of BRAF-mutant conventional melanoma harboring Spitzoid morphology: a case report

BACKGROUND

Spitzoid melanocytic lesions represent a heterogeneous group of proliferations with ambiguous and overlapping terminology. The exact distinction of a Spitz nevus from a Spitzoid melanoma can be very difficult or, in some cases, impossible. Among the Spitzoid lesions, there is a lesion termed an atypical Spitz tumour (AST) that has intermediate histopathologic features between those of a Spitz nevus and a Spitzoid melanoma and thus uncertain malignant potential. There are several rare cases of patients with a Spitzoid melanoma initially misdiagnosed as a Spitz nevus or an AST with fatal consequences. It is, therefore, advised to perform a molecular characterization in cases where uncertain skin lesions are presented, as it may provide extended set of information with a possible impact on the treatment options. Furthermore, preventive measures, such as regular physical and skin examinations, as well as thorough scheduling of individual follow-up visits, are essential in patients with potentially malignant skin nevi.

CASE REPORT

We report a case of a young adult female with a history of AST excision with a negative sentinel lymph node biopsy (SLNB) and insufficient follow-up. Four years after the primary dermatological diagnosis, she presented with a giant tumour in the right hemithorax. Radical en bloc resection of the tumour with right pneumonectomy and resection of the pericardium with reconstruction of the pericardium using mesh was performed. A definitive histopathological examination revealed a metastatic melanoma. The association of the previously diagnosed AST and subsequent appearance of melanoma metastases led to a retrospective re-evaluation of the initial lesion. The suspected diagnosis of Spitzoid melanoma, however, was not confirmed. Moreover, the molecular examination revealed a major discordance between the initial lesion and the lung tumour, which most likely excluded the possible association of the lung metastasis with the initial skin lesion. The initial skin lesion was a BRAF-mutant melanoma with Spitzoid features and termed as AST, while the giant lung metastasis was NRAS-mutant melanoma. The subsequent postoperative course was complicated by the appearance of brain metastases that were stereotactically irradiated. Nevertheless, despite complex specialised medical care, the patient's clinical condition rapidly deteriorated. By this time, no active oncological treatment was possible. The patient was delegated to local hospice for palliative care six months after the surgery and died three weeks later.

CONCLUSIONS

Our patient was surgically treated at the age of 20 for AST and died four years later of metastatic NRAS-mutant melanoma most likely of different occult origin. Molecular characterization, as well as the close clinical follow-up should be always precisely performed in patients with uncertain skin lesions, such as AST.

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.

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.

Spitz nevus, Spitz tumor, and spitzoid melanoma: a comprehensive clinicopathologic overview

Spitz nevus can clinically present either in the classical (reddish pink) or the pigmented (brownish black) variant. Dermoscopy demonstrates that the pigmented variant is much more common than the classical variant; however, none of these show dermoscopic patterns clearly distinguishable from melanoma. Even histopathologically, a clear-cut differentiation between benign and malignant spitzoid neoplasms is often difficult, so that intermediate diagnostic categories (atypical Spitz nevus and Spitz tumor) are admitted. Because of these difficulties in clinical and histopathologic evaluation, surgical excision is recommended for clinically atypical spitzoid lesions of childhood and for all spitzoid lesions of adulthood.

Clinicopathologic features and survival in Spitzoid malignant melanoma and conventional malignant melanoma

BACKGROUND

Although recent advances in genetics have revealed distinct mutational profiles and molecular signaling pathways associated with Spitzoid malignant melanoma (SMM), less is known about the clinicopathologic characteristics and behavior of SMM compared with conventional melanoma.

OBJECTIVE

We sought to determine the clinicopathologic characteristics and mortality risk associated with SMM and conventional malignant melanoma.

METHODS

We conducted a retrospective study of 30 patients with SMM and 30 patients with conventional melanoma. The two groups were matched by age, gender, and depth of tumor invasion. Additional patient- and tumor-level characteristics were compared between groups and regression modeling was used to assess relative mortality risk.

RESULTS

Unadjusted analyses of SMM and conventional malignant melanoma revealed no significant differences in clinical impression, anatomic location, mitotic rate, and presence of ulceration. Sentinel lymph node biopsy, completion lymphadenectomy, and visceral metastases did not differ between groups. Cox proportional hazards regression showed no differences in mortality between Spitzoid and conventional melanoma.

LIMITATIONS

Small sample size, short follow-up duration, and residual confounding may limit the accuracy and generalizability of our results.

CONCLUSIONS

SMM and conventional malignant melanoma differ in some clinicopathologic features. We did not find a statistically significant difference in mortality between the two.

Cutaneous malignant melanoma: update on diagnostic and prognostic biomarkers

The incidence of cutaneous malignant melanoma has rapidly increased in recent years in all parts of the world, and melanoma is a leading cause of cancer death. As even relatively small melanomas may have metastatic potential, accurate assessment of progression is critical. Although diagnosis of cutaneous malignant melanoma is usually based on histopathologic criteria, these criteria may at times be inadequate in differentiating melanoma from certain types of benign nevi. As for prognosis, tumor (Breslow) thickness, mitotic rate, and ulceration have been considered the most important prognostic indicators among histopathologic criteria. However, there are cases of thin primary melanomas that have ultimately developed metastases despite complete excision. Given this, an accurate assessment of melanoma progression is critical, and development of molecular biomarkers that identify high-risk melanoma in its early phase is urgently needed. Large-scale genomic profiling has identified considerable heterogeneity in melanoma and suggests subgrouping of tumors by patterns of gene expression and mutation will ultimately be essential to accurate staging. This subgrouping in turn may allow for more targeted therapy. In this review, we aim to provide an update on the most promising new biomarkers that may help in the identification and prognostication of melanoma.

Imaging mass spectrometry--a new and promising method to differentiate Spitz nevi from Spitzoid malignant melanomas

BACKGROUND

Differentiating Spitz nevus (SN) from Spitzoid malignant melanoma (SMM) is one the most difficult problems in dermatopathology.

SPECIFIC AIM

To identify differences on proteomic level between SN and SMM.

METHODS

We performed Imaging Mass Spectrometry analysis on formalin-fixed, paraffin-embedded tissue samples to identify differences on proteomic level between SN and SMM. The diagnosis of SN and SMM was based on histopathologic criteria, clinical features, and follow-up data, which confirmed that none of the lesions diagnosed as SN recurred or metastasized. The melanocytic component (tumor) and tumor microenvironment (dermis) from 114 cases of SN and SMM from the Yale Spitzoid Neoplasm Repository were analyzed. After obtaining mass spectra from each sample, classification models were built using a training set of biopsies from 26 SN and 25 SMM separately for tumor and for dermis. The classification algorithms developed on the training data set were validated on another set of 30 samples from SN and 33 from SMM.

RESULTS

We found proteomic differences between the melanocytic components of SN and SMM and identified 5 peptides that were differentially expressed in the 2 groups. From these data, 29 of 30 SN and 26 of 29 SMM were recognized correctly based on tumor analysis in the validation set. This method correctly classified SN with 97% sensitivity and 90% specificity in the validation cohort.

CONCLUSIONS

Imaging Mass Spectrometry analysis can reliably differentiate SN from SMM in formalin-fixed, paraffin-embedded tissue based on proteomic differences.

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.

Genetic alterations in childhood melanoma

Melanoma is rare in children. However, the clinical features of the disease in this population have been well-documented through single-institution experiences and population-based analyses. Still, our understanding of the etiologic factors in children remains unclear and diagnosis of melanoma remains challenging in certain cases. This article reviews emerging evidence indicating that molecular characterization of these lesions in children may be of diagnostic and therapeutic value.

Atypical Spitzoid melanocytic tumors: a morphological, mutational, and FISH analysis

BACKGROUND

Identification of the clinical behavior of atypical Spitzoid tumors with conflicting histopathologic features remains controversial.

OBJECTIVE

We sought to assess whether molecular findings may be helpful in the diagnostic and prognostic assessment of atypical Spitzoid tumors.

METHODS

A total of 38 controversial, atypical Spitzoid lesions (≥ 1 mm in thickness) were analyzed for clinicopathological features, chromosomal alterations by fluorescence in situ hybridization (FISH) analysis (RREB1/MYB/CCND1/CEP6), BRAF(V600E) mutation by allele-specific real-time polymerase chain reaction confirmed by sequencing, and H-RAS gene mutation by direct sequencing.

RESULTS

Atypical Spitzoid lesions developed in 21 female and 17 male patients (mean age 22 years). Nine patients underwent sentinel lymph node biopsy and a sentinel lymph node micrometastasis was detected in 4 of these 9 cases. Four additional patients, who did not receive a sentinel lymph node biopsy, experienced bulky lymph node metastases and one experienced visceral metastases and death. Lesions from patients with lymph node involvement showed more deep mitoses (P < .01), less inflammation (P = .05), and more plasma cells (P = .04). FISH analysis demonstrated the presence of chromosomal alterations in 6 of 25 cases. Correlation with follow-up data showed that the only case with fatal outcome showed multiple chromosomal alterations by FISH analysis. BRAF(V600E) mutation was detected in 12 of 16 cases (75%) and H-RAS mutation on exon 3 was found in 3 of 11 cases (27%).

LIMITATIONS

Our results require validation in a larger series with longer follow-up information.

CONCLUSIONS

FISH assay may be of help in the prognostic evaluation of atypical Spitzoid tumors. Diagnostic significance of BRAF(V600E) and H-RAS mutations in this setting remains unclear.

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.

Frequencies of BRAF and NRAS mutations are different in histological types and sites of origin of cutaneous melanoma: a meta-analysis

BACKGROUND

There have been conflicting data regarding the prevalence and clinicopathological characteristics of BRAF and NRAS mutations in primary cutaneous melanoma.

OBJECTIVES

To solve this controversy, this study used a meta-analysis to evaluate the frequencies of BRAF and NRAS mutations, and the relationship between these mutations and clinicopathological parameters of cutaneous melanoma.

METHODS

Data from studies published between 1989 and 2010 were combined. The BRAF and NRAS mutations were reported in 36 and 31 studies involving 2521 and 1972 patients, respectively. The effect sizes of outcome parameters were calculated by odds ratios (OR).

RESULTS

BRAF and NRAS mutations were reported in 41% and 18% of cutaneous melanomas, respectively. The mutations were associated with histological subtype and tumour site, but not with age and sex. The BRAF mutation was frequently detected in patients with superficial spreading melanoma (OR=2·021; P<0·001) and in melanomas arising in nonchronic sun-damaged skin (OR=2·043; P=0·001). In contrast, the NRAS mutation was frequently evident in patients with nodular melanoma (OR=1·894; P<0·001) and in melanomas arising in chronic sun-damaged skin (OR=1·887; P=0·018).

CONCLUSIONS

This pooled analysis shows that the incidences of BRAF and NRAS mutations in cutaneous melanomas differ according to histological type and tumour location based on the degree of sun exposure.

The classification of cutaneous melanoma

Forty years ago, a clinical and histological classification scheme and prognostic factors were described for cutaneous melanoma. This scheme included the subtypes superficial spreading, nodular and lentigo maligna, and prognostic factors including tumor thickness, ulceration, and mitotic activity. There have been some tweaks to the classification scheme, but these basic findings form the foundation for melanoma diagnosis and staging today. Currently, no molecular marker or target has proved reliably useful in the staging or treatment of melanoma. Measurement with a simple ruler serves as the basis for the staging of primary cutaneous melanoma, while the recognition of primary tumor mitotic activity and ulceration also remain significant factors. Recently, mutational analysis has revealed a correlation of activating mutations with the morphological descriptors from decades ago. Future classification schemes may have more power in predicting response to therapy by integrating specific genomic and intra-tumoral expression profiles with histologic findings.

BRAF, NRAS and HRAS mutations in spitzoid tumours and their possible pathogenetic significance

BACKGROUND

The relationships between so-called spitzoid tumours have proven difficult to understand.

OBJECTIVES

To address three questions: does spitzoid tumour morphological similarity reflect molecular similarity? Does Spitz naevus progress into spitzoid melanoma? Are ambiguous spitzoid tumours genuine entities?

METHODS

BRAF, NRAS and HRAS mutations were analysed using single-strand conformational polymorphism analysis and sequencing.

RESULTS

Both Spitz naevi and spitzoid melanoma had a lower combined BRAF and NRAS mutation frequency compared with common acquired naevi (P = 0.0001) and common forms of melanoma (P = 0.0072), respectively. To look for evidence of progression from Spitz naevi to spitzoid melanoma, HRAS was analysed in 21 spitzoid melanomas, with no mutations identified. The binomial probability of this was 0.03 based on an assumption of a 15% mutation frequency in Spitz naevi with unbiased progression. Under these assumptions, HRAS mutations must be rare/absent in spitzoid melanoma. Thus, Spitz naevi seem unlikely to progress into spitzoid melanoma, implying that ambiguous spitzoid tumours cannot be intermediate degrees of progression. In addition, the data suggest that HRAS mutation is a potential marker of benign behaviour, in support of which none of three HRAS mutant spitzoid cases metastasized.

CONCLUSIONS

First, the morphological similarity of spitzoid tumours reflects an underlying molecular similarity, namely a relative lack of dependence on BRAF/NRAS mutations. Second, Spitz naevi do not appear to progress into spitzoid melanoma, and consequently ambiguous spitzoid tumours are likely to be unclassifiable Spitz naevi or spitzoid melanoma rather than genuine entities. Third, HRAS mutation may be a marker of Spitz naevus, raising the possibility that other molecular markers for discriminating Spitz naevi from spitzoid melanoma can be discovered.

Cutaneous melanoma subtypes show different BRAF and NRAS mutation frequencies

PURPOSE

BRAF mutations are present in two thirds of cutaneous melanomas and many of the rest have NRAS mutations. However, cutaneous melanoma is a heterogeneous disease with many clinicopathologic subtypes. Of these, the majority fits into four categories: superficial spreading, nodular, lentigo maligna, and acral lentiginous melanoma (ALM). Thus far, there is very limited data combining BRAF and NRAS mutation analysis to explore differences between cutaneous melanoma subtypes. The aim of this study was to address this issue.

EXPERIMENTAL DESIGN

The frequency of BRAF and NRAS hotspot mutations, in exons 15 and 2, respectively, was assessed in 59 cutaneous melanomas comprising superficial spreading, nodular, lentigo maligna, and ALM using single-strand conformational polymorphism and RFLP-PCR analysis.

RESULTS

Only 2 of 21 (9.5%) ALM showed BRAF exon 15 mutation compared with 9 of 14 (64.3%) superficial spreading malignant melanomas, 4 of 11 (36.4%) nodular melanomas, and 7 of 13 (53.4%) lentigo maligna melanomas (P < 0.01). However, our key finding is that the combined analysis of BRAF exon 15 and NRAS exon 2 showed that there were no significant differences in the overall mutation frequency between subtypes. In particular, 9 of 19 (47.4%) ALM without BRAF exon 15 mutation had an NRAS exon 2 mutation.

CONCLUSIONS

We show that the overall BRAF/NRAS frequency in mutation hotspots is not significantly different among cutaneous melanoma subtypes. These data show that mitogen-activated protein kinase pathway activation may be important in all major subtypes of cutaneous melanoma, although the mechanism by which this is achieved varies.

Understanding spitzoid tumours: new insights from molecular pathology

Spitzoid tumours are a morphologically diverse group of lesions that share histological similarity to the Spitz naevus, a benign melanocytic skin tumour. Distinguishing classic Spitz naevi from cutaneous malignant melanoma is usually achievable on standard histology sections, but occasionally equivocal lesions are encountered that show features intermediate between these two entities and consequently generate considerable clinical and histopathological concern. The nomenclature and diagnostic criteria for spitzoid lesions are not standardized and this article begins by considering the adverse effect this has on our understanding of spitzoid tumour biology. Investigations of some of the hallmark features of cancer and neoplasia in spitzoid tumours are described, and the contribution of these studies to our understanding of spitzoid tumour biology is considered, along with their potential diagnostic utility. These studies compare spitzoid tumours with better-characterized melanocytic lesions, and from such comparisons assumptions concerning the biological nature of different spitzoid tumours can be made. In contrast, investigations of the mitogen-activated protein kinase (MAPK) pathway and DNA gains and losses have suggested that Spitz naevi may be genetically distinct from other melanocytic tumours. The studies that led to this conclusion are reviewed, as well as subsequent work examining whether the same applies to all spitzoid tumours. Possible explanations for the considerable inconsistencies within some of these data are explored. Finally, potential pathways of tumour progression within spitzoid lesions are considered, with an emphasis placed upon insights gained from investigations of MAPK genes and DNA gains and losses.

Genetic and epigenetic alterations in the differential diagnosis of malignant melanoma and spitzoid lesion

BACKGROUND

The histopathological differentiation of malignant melanoma and Spitz naevus often presents diagnostic problems.

OBJECTIVES

We aimed to find out applicable diagnostic parameters other than routine pathology.

METHODS

The cases included conventional melanomas and Spitz naevi as well as atypical spitzoid lesions that had posed diagnostic difficulties. We examined hotspots of mutation in the BRAF, NRAS and HRAS genes by polymerase chain reaction-based direct sequencing. We also analysed DNA copy number aberrations and the methylation of CpG sequences in several cancer-related genes by utilizing a novel methylation-specific multiplex ligation-dependent probe amplification method.

RESULTS

Twenty three of 24 conventional melanomas showed at least one of the genetic and epigenetic alterations examined, although one acral melanoma did not show any alteration. By sharp contrast, 12 Spitz naevi with an unambiguous histopathology showed no or few chromosomal aberrations, no oncogene mutations and no methylation of CpG sequences. Of the 16 ambiguous spitzoid lesions, most of which were designated atypical Spitz tumour by one of the authors, all but one showed no mutations, no methylations and few copy number aberrations. However, three tumours showed copy number loss of the cyclin-dependent kinase inhibitor 2A gene (CDKN2A), an alteration observed frequently in melanomas but not found in conventional Spitz naevi. These results show that, although most atypical Spitz tumours do not differ from conventional Spitz naevi showing virtually no genetic and epigenetic aberrations, some cases may have chromosomal aberrations that include copy number loss of the CDKN2A gene.

CONCLUSIONS

Genetic and epigenetic analyses may be useful as an additional diagnostic tool to distinguish between melanoma and Spitz naevus, and may help to define subgroups in atypical Spitz tumours.

Influence of age on survival in childhood spitzoid melanomas

BACKGROUND

Melanoma occurring during childhood and adolescence is rare. Although a few limited studies suggest that the prognosis of childhood melanomas is similar to those in adults, and is dependent on the initial stage of the tumor, there is controversy with respect to the biologic behavior of childhood melanomas. Spitzoid melanoma is a subtype of melanoma with distinct clinical and histopathologic features. The prognosis of spitzoid melanoma in children, despite metastasis, has been suggested to be better than that observed in adults; however, this assertion remains controversial. Whereas a number of spitzoid melanomas with regional lymph node metastasis with no further progression have been reported, cases leading to widespread metastasis and fatal outcomes are also well documented.

METHODS

A retrospective review of the literature was conducted between 1949 and 2006. A total of 82 cases of spitzoid melanoma with regional and/or widespread metastasis that occurred in children, 17 years of age and under, were selected for the analysis.

RESULTS

The 5-year survival rate in children diagnosed with metastatic spitzoid melanomas between 0 and 10 years of age was 88% compared with 49% in those between 11 and 17 years of age.

CONCLUSIONS

The findings support the notion that younger age (< or =10) may be associated with longer survival in children with metastatic spitzoid melanomas.