The dermal-based borderline melanocytic tumor: A categorical approach

PRAME and Historical Immunohistochemical Antibodies Ki-67, P16, and HMB-45 in Ambiguous Melanocytic Tumors

ABSTRACT

Ambiguous melanocytic lesions/tumors (AMLs) can be simply described as melanocytic neoplasms that cannot be differentiated as either a melanoma or a nevus. Preferentially expressed antigen in melanoma (PRAME) is a novel antibody that can help differentiate between nevi and melanomas. However, its usefulness remains controversial in AMLs. The aim of this study was to demonstrate the importance of PRAME and diagnostic auxiliary antibodies (Ki-67, p16, HMB-45) in the diagnosis of melanocytic lesions, especially in AMLs. This study included 52 ambiguous melanocytic lesions, 40 nevi, and 40 melanomas. All immunohistochemical studies were performed automatically using the Universal Alkaline Phosphatase Red Detection Kit. Different analytic approaches were used for each antibody based on the literature. Statistically, the multinomial forward stepwise elimination logistic regression analysis was used to create a statistical model to predict the diagnosis of melanocytic lesions based on clinical, morphological, and immunohistochemical data. PRAME positivity was very strong and diffuse in the melanoma group and statistically significantly higher than that of the AML and nevus groups. There was no statistically significant difference between the nevus and AML groups. The Ki-67 proliferation index and HMB-45 staining pattern provided valuable indications for distinguishing between these 3 groups. The P16 antibody was limited in supporting the differential diagnosis. Our statistical model showed that a high mitosis count, central pagetoid spread, and PRAME positivity increased the probability of melanoma against an AML diagnosis. This study showed the advantages of evaluating the PRAME antibody together with morphological features and other immunohistochemical markers (Ki-67 and HMB-45) in the differential diagnosis of melanocytic lesions.

PRKC Fusion Melanocytic Tumors, a Subgroup of Melanocytic Tumors More Closely Aligned to Blue Nevi Than to PRKAR1A-inactivated Pigmented Epithelioid Melanocytomas

Tumors morphologically classified as pigmented epithelioid melanocytomas (PEMs) are genomically diverse, with the 2 most common genomic subtypes being PRKC fusions or PRKAR1A inactivating mutations. PRKC fusions activate the Gαq/11 pathway similar to blue nevi. Conversely, inactivating mutations in PRKAR1A activate the Gαs pathway. We hypothesize that PRKC fusions have greater genomic overlap with blue nevi compared with PRKAR1A-inactivated PEMs. We characterized the clinical and morphologic features of 21 PRKC and PRKACB fusion melanocytic tumors and compared this to PRKAR1A mutated PEMs. To test our hypothesis regarding greater genomic overlap between PRKC fusions and blue nevi relative to PRKAR1A mutated PEMs, we performed a principal component analysis (PCA) using mRNA expression data. Lastly, we performed a meta-analysis focusing on the outcome data of PRKC fusions. PRKC fusions occur at a younger median age than PRKAR1A mutated PEMs (16 vs. 27). Histologically, PRKC fusions have solid aggregates of epithelioid melanocytes not typical of PRKAR1A mutated PEMs. The PCA plot showed no overlap between the PRKC fusion group and the PRKAR1A-mutated PEMs. There was a significant overlap between PRKC fusions and blue nevi. A meta-analysis of PRKC fusion cases in the literature suggests melanoma is uncommon, but the loss of BAP-1 nuclear expression may be associated with an adverse prognosis as in tumors from the blue nevus family. PRKC fusion melanocytic tumors have greater genomic overlap with blue nevi compared with PRKAR1A mutated PEMs. We recommend categorizing benign PRKC fusion melanocytic tumors as blue fusion nevi/tumors.

A clinical impact study of dermatologists' use of diagnostic gene expression profile testing to guide patient management

Aim: Cutaneous melanocytic neoplasms with diagnostic and/or clinical ambiguity pose patient management challenges. Methods: Six randomized case scenarios with diagnostic/clinical uncertainty were described with/without a benign or malignant diagnostic gene expression profile (GEP) result. Results: Clinical impact was assessed by reporting the mean increase/decrease of management changes normalized to baseline (n = 32 dermatologists). Benign GEP results prompted clinicians to decrease surgical margins (84.2%). Malignant GEP results escalated surgical excision recommendations (100%). A majority (72.2%) reduced and nearly all (98.9%) increased follow-up frequency for benign or malignant GEP results, respectively. There was an overall increase in management plan confidence with GEP results. Conclusion: Diagnostic GEP tests help guide clinical decision-making in a variety of diagnostically ambiguous or clinicopathologically discordant scenarios.

Conventional and Atypical Deep Penetrating Nevus, Deep Penetrating Nevus-like Melanoma, and Related Variants

Simple Summary

Atypical deep penetrating nevus (DPN) is a unique skin tumor with an uncertain biologic/metastatic potential that may be difficult to distinguish from DPN (an indolent lesion) and DPN-like melanoma (an aggressive lesion) based on the results of histomorphologic analysis and commonly employed molecular studies such as fluorescence in situ hybridization and comparative genomic hybridization alone. Herein, we review the clinical, histomorphological, immunohistochemical, molecular, and cytogenetic characteristics of the DPN spectrum of lesions to try to better understand the prognosis of these lesions and possible treatment approaches.

Abstract

Deep penetrating nevus (DPN) is an uncommon acquired melanocytic lesion with a distinct histopathological appearance that typically behaves in an indolent manner. The lesion is characterized by a symmetrical proliferation of epithelioid to spindled melanocytes associated with abundant melanophages and wedge-shaped extension to the deep reticular dermis and subcutis. Pronounced cytologic atypia and mitotic figures are usually absent, which helps distinguish DPN from melanoma with a deep penetrating growth pattern. Recently, the concept of atypical DPN has been proposed for lesions that demonstrate borderline histomorphologic features and may be associated with lymph node deposits but lack the copy number aberrations typical of melanoma by either fluorescence in situ hybridization or comparative genomic hybridization. While most of these lesions have a favorable clinical course, rare lesions may progress to melanoma. In this review, we summarize the current literature on atypical DPNs with uncertain behavior/metastatic potential and outline the characteristics that distinguish these lesions from conventional DPN and melanoma with DPN-like features.

Characterization of multiple diagnostic terms in melanocytic skin lesion pathology reports

BACKGROUND

Histopathologically ambiguous melanocytic lesions lead some pathologists to list multiple diagnostic considerations in the pathology report. The frequency and circumstance of multiple diagnostic considerations remain poorly characterized.

METHODS

Two hundred and forty skin biopsy samples were interpreted by 187 pathologists (8976 independent diagnoses) and classified according to a diagnostic/treatment stratification (MPATH-Dx).

RESULTS

Multiple diagnoses in different MPATH-Dx classes were used in n = 1320 (14.7%) interpretations, with 97% of pathologists and 91% of cases having at least one such interpretation. Multiple diagnoses were more common for intermediate risk lesions and are associated with greater subjective difficulty and lower confidence. We estimate that 6% of pathology reports for melanocytic lesions in the United States contain two diagnoses of different MPATH-Dx prognostic classes, and 2% of cases are given two diagnoses with significant treatment implications.

CONCLUSIONS

Difficult melanocytic diagnoses in skin may necessitate multiple diagnostic considerations; however, as patients increasingly access their health records and retrieve pathology reports (as mandated by US law), uncertainty should be expressed unambiguously.

Interpretation of the Complex Melanoma Pathology Report

An ambiguous pathologic report can present a clinical dilemma to the treating surgeon. We describe lesions ranging from the potentially benign to the likely malignant. Correctly identifying features associated with higher-risk lesions has proven challenging given the overall good prognosis and low rate of events. An appropriate treatment plan generally requires discussion between the surgeon and an experienced dermatopathologist. When clinically indicated, additional testing may be used to further support or refute a diagnosis of melanoma. The indications for these techniques, the data to support their use, and the strengths and weakness of each are reviewed.

Diagnosis of melanoma by imaging mass spectrometry: Development and validation of a melanoma prediction model

BACKGROUND

The definitive diagnosis of melanocytic neoplasia using solely histopathologic evaluation can be challenging. Novel techniques that objectively confirm diagnoses are needed. This study details the development and validation of a melanoma prediction model from spatially resolved multivariate protein expression profiles generated by imaging mass spectrometry (IMS).

METHODS

Three board-certified dermatopathologists blindly evaluated 333 samples. Samples with triply concordant diagnoses were included in this study, divided into a training set (n = 241) and a test set (n = 92). Both the training and test sets included various representative subclasses of unambiguous nevi and melanomas. A prediction model was developed from the training set using a linear support vector machine classification model.

RESULTS

We validated the prediction model on the independent test set of 92 specimens (75 classified correctly, 2 misclassified, and 15 indeterminate). IMS detects melanoma with a sensitivity of 97.6% and a specificity of 96.4% when evaluating each unique spot. IMS predicts melanoma at the sample level with a sensitivity of 97.3% and a specificity of 97.5%. Indeterminate results were excluded from sensitivity and specificity calculations.

CONCLUSION

This study provides evidence that IMS-based proteomics results are highly concordant to diagnostic results obtained by careful histopathologic evaluation from a panel of expert dermatopathologists.

Deep Penetrating Nevus and Borderline-Deep Penetrating Nevus: A Literature Review

Deep penetrating nevi (DPN) are rare melanocytic nevi, which can exhibit atypical histological features hampering the differentiation from malignant melanoma. DPN are considered benign melanocytic lesions, but rare spread to lymph nodes and unfavorable clinical outcomes associated with borderline/atypical DPN (B-DPN) has been reported. Since no guidelines are available for DPN and B-DPN, we aimed to review the literature on DPN and B-DPN to assess the management and prognosis. We screened 3,513 references from EMBASE, Scopus and Medline databases, and included 15 studies with a total of 355 DPN patients and 48 B-DPN patients. Therapeutic interventions ranged from simple excision to wide excisions and sentinel lymph node biopsy (SLNB), with block lymph node dissection in some positive SLNB cases. Follow-up periods ranged from 3 months to 23 years during which a total of five recurrences, two in DPN and three in B-DPN group, and three metastases, in B-DPN group, were reported. While some of the included studies comprised clinical and histopathological correlation, few included genetic assessment. The present review highlights the need for prospective cohort studies applying composite measures to identify effective regimens of diagnostic workup and treatment in DPN and B-DPN.

Atypical Melanocytic Proliferations: A Review of the Literature

BACKGROUND

Ambiguous histopathologic diagnoses represent a challenge for clinicians because of a lack of definitive diagnosis and related uncertainty about management.

OBJECTIVE

To review the literature on atypical melanocytic proliferations and detail synonymous terms, epidemiology, diagnostic work-up, histopathology, treatment, and prognosis.

METHODS

Databases from PubMed and Web of Science were searched for articles related to atypical melanocytic proliferations.

RESULTS

Intraepidermal melanocytic proliferations with features worrisome for possible melanoma in situ (MIS) are generally excised as for MIS. Reported rates of upstaging of such cases to invasive melanoma on review of the excision are very low. Because invasion, lymph node spread, and metastasis can occur in atypical melanocytic lesions with a thick intradermal component, these are often treated as for malignant melanoma.

CONCLUSION

Because the diagnosis dictates treatment, it is incumbent to establish a diagnosis as definitive as possible, obtaining second or third opinions and using ancillary studies when appropriate. When the diagnosis remains uncertain, it is difficult to provide guidelines for treatment. Clinical care decisions for patients with an uncertain diagnosis are best done on a case-by-case basis weighing probabilities of adverse outcomes against potential benefits and risks from various treatment options.

The correlation of the standard 5 probe FISH assay with melanocytic tumors of uncertain malignant potential

BACKGROUND

FISH has recently emerged as a technique to better assess the malignant potential of histologically ambiguous melanocytic lesions. However, the usefulness of FISH has not been conclusively established. The purpose of this study was to further explore the diagnostic value of FISH in distinguishing the borderline melanocytic tumor (BMT) from melanoma.

METHOD

73 cases with BMT were analyzed retrospectively from a dermatopathology database between 2010-2015. FISH studies were conducted in each case using probes targeting 5 loci including CCND1 on 11q13, RREB1 on 6p25, MYB on 6q23, CDKN2A on 9p21, and CEP 6 control probe for chromosome 6.

RESULTS

The study was composed of 50 females and 23 males with an age range of 1-73 and a mean age of 35years. Of the 6 cases in the superficial atypical Spitz tumor (AST) category, 2 had indeterminate results due to polyploidy. In the conventional atypical Spitz tumor cases, FISH was positive in 3 of 15 cases. Of the 27 cases in the borderline nevoid tumor (BNM) category, 3 showed positive FISH and 3 were equivocal due to the possibility of polyploidy. 3 of 13 cases of the borderline tumor of deep penetrating nevus variant (B-DPN) were positive for FISH. Neither of the 2 pigmented epithelioid melanocytoma (PEM) cases had positive FISH result. Of the 4 cases in the superficial atypical dermoepidermal nevomelanocytic proliferation group, only 1 met the FISH diagnostic criteria for melanoma. None of the 6 borderline tumors with overlapping features met FISH criteria diagnostic of melanoma. Clinical follow up was available on 55 patients. None of the patients had recurrence nor died of the disease. Lymph node biopsy was performed on five patients without evidence of metastasis.

CONCLUSION

Despite the benefits of FISH, it is limited by the fact that melanomas are not genetically identical whereby certain genetic abnormalities are only seen in specific subtypes. Additionally, FISH only targets specific chromosomes resulting in limitations in sensitivity and specificity. Although FISH has proven to be highly sensitive and specific in distinguishing unequivocally benign from malignant lesions, in cases of histopathological ambiguity, these parameters cannot be assessed with great confidence because the histopathological diagnosis (gold standard) is not without uncertainty. The 4-probe set (excluding 9p21) consistently showed chromosomal aberrations throughout all groups, but only 10 of the 73 total cases (13%) met the diagnostic criteria for melanoma. Moreover, it would be wise to establish new cytogenetic reference values that incorporate these borderline lesions in an effort to better assess the possibility of malignant behavior and or define a cytogenetic profile supportive of its categorization as an indeterminate proliferation. Polyploidy is another inherent limitation, which leads to false positives due to the absolute signal counts incorrectly reflecting relative imbalances in the tumor genome.

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 deep penetrating nevus

The deep penetrating nevus (DPN), also known as the plexiform spindle cell nevus, is a pigmented lesion that commonly arises on the head and neck in the first few decades of life. Histopathologically, the DPN is wedge-shaped and contains melanocytes that exhibit deep infiltration into the dermis. Given these features, DPN may clinically and histopathologically mimic malignant melanoma, sparking confusion about the appropriate evaluation and management of these lesions. The goal of this review is to summarize the clinical and histopathological features of DPN and to discuss diagnostic and treatment strategies for dermatologists.

Atypical Spitz tumours and sentinel lymph node biopsy: a systematic review

Sentinel lymph node biopsy has been proposed as a diagnostic method for estimation of the malignant potential of atypical Spitz tumours. However, although cell deposits are commonly detected in the sentinel lymph nodes of patients with atypical Spitz tumours, their prognosis is substantially better than that of patients with melanoma and positive sentinel lymph node biopsies. We did a systematic review of published reports to assess the role of sentinel lymph node biopsy as a prognostic method in the management of atypical Spitz tumours. The results of our analysis did not show any prognostic benefit of sentinel lymph node biopsy; having a positive sentinel lymph node does not seem to predict a poorer outcome for patients with atypical Spitz tumours. These findings indicate that, especially in the paediatric population, it might be prudent initially to use complete excision with clear margins and careful clinical follow-up in patients with atypical Spitz tumours.

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.

Identification of HRAS mutations and absence of GNAQ or GNA11 mutations in deep penetrating nevi

HRAS is mutated in ∼15% of Spitz nevi, and GNAQ or GNA11 is mutated in blue nevi (46-83% and ∼7% respectively). Epithelioid blue nevi and deep penetrating nevi show features of both blue nevi (intradermal location, pigmentation) and Spitz nevi (epithelioid morphology). Epithelioid blue nevi and deep penetrating nevi can also show overlapping features with melanoma, posing a diagnostic challenge. Although epithelioid blue nevi are considered blue nevic variants, no GNAQ or GNA11 mutations have been reported. Classification of deep penetrating nevi as blue nevic variants has also been proposed, however, no GNAQ or GNA11 mutations have been reported and none have been tested for HRAS mutations. To better characterize these tumors, we performed mutational analysis for GNAQ, GNA11, and HRAS, with blue nevi and Spitz nevi as controls. Within deep penetrating nevi, none demonstrated GNAQ or GNA11 mutations (0/38). However, 6% revealed HRAS mutation (2/32). Twenty percent of epithelioid blue nevi contained a GNAQ mutation (2/10), while none displayed GNA11 or HRAS mutation. Eighty-seven percent of blue nevi contained a GNAQ mutation (26/30), 4% a GNA11 mutation (1/28), and none an HRAS mutation. Within Spitz nevi, none demonstrated GNAQ or GNA11 mutations (0/30). Seventeen percent contained an HRAS mutation (5/30). All GNAQ and GNA11 mutations were p.Q209L (c.626A>T) point mutations, except 2 GNAQ mutations, which contained novel c.625_626CA>TT double mutations. Four HRAS mutations were in exon 2, and three in exon 3. This is the first study to identify HRAS mutations in deep penetrating nevi. The presence of HRAS mutations and absence of GNAQ or GNA11 mutations in deep penetrating nevi suggests classification of these unusual nevi within the Spitz nevus category of melanocytic tumors, rather than the blue nevus category.

Lymphatic invasion predicts aggressive behavior in melanocytic tumors of uncertain malignant potential (MELTUMP)

Lymphatic invasion (LI) identified by immunohistochemical (IHC) staining is common in primary cutaneous melanoma, and LI has been shown to be an independent prognostic factor in melanoma. Its prognostic significance in melanocytic tumors of uncertain malignant potential (MELTUMPs) has not been well characterized. This study included 32 patients with provisional diagnoses of MELTUMP. Lesions were evaluated for tumor thickness, the presence of ulceration, mitotic figures, mitotic figures at the base, tumor infiltrating lymphocytes, as well as peritumoral and intratumoral lymphatic density. Dual IHC staining was used to microscopically detect lymphatic endothelium (podoplanin) containing melanoma cells (S100), with the aid of multispectral imaging in select cases. Univariate analysis was performed to identify associations between clinical and pathologic variables and melanoma-related events. The 32 patients had a median follow-up of 111 months. Two patients subsequently died of melanoma-related disease, 1 died of unknown causes, 5 developed nodal metastases, and the remainder showed no evidence of progressive disease. LI was identified in 8/32 patients (25%) by dual IHC staining, which included the 2 patients who died of melanoma-related disease, 1 patient with bulky nodal metastasis, 1/4 patients with microscopic nodal metastases, and 4 patients who showed no evidence of progressive disease. The presence of LI was associated with melanoma metastases or melanoma-related death (P=0.05). The presence of LI by dual IHC in MELTUMPs is associated with a poorer prognosis, specifically with melanoma metastasis, and may therefore serve as a useful prognostic factor for risk stratification of patients with these diagnostically challenging lesions.

Main clues in the pathologic diagnosis of melanoma: is molecular genetics helping?

Although conventional histopathologic examination is still the undisputable mainstay for the diagnosis of melanocytic skin neoplasms, application of molecular testing has experienced tremendous growth and will continue to expand in the future as the need for more specific diagnoses and new targeted therapies evolve. Ancillary molecular methods, including comparative genomic hybridization and fluorescence in situ hybridization, have the potential to provide important new information to challenging cases, and will help improve diagnostic accuracy, particularly in cases in which morphology is not conclusive. Pathologists are increasingly involved in the prospective genotyping of melanoma, which leads to patient stratification in light of the novel personalized therapeutic approaches in the advanced setting.

Sentinel lymph node biopsy in nonmelanoma skin cancer patients

The management of lymph nodes in nonmelanoma skin cancer patients is currently still debated. Merkel cell carcinoma (MCC), squamous cell carcinoma (SCC), pigmented epithelioid melanocytoma (PEM), and other rare skin neoplasms have a well-known risk to spread to regional lymph nodes. The use of sentinel lymph node biopsy (SLNB) could be a promising procedure to assess this risk in clinically N0 patients. Metastatic SNs have been observed in 4.5-28% SCC (according to risk factors), in 9-42% MCC, and in 14-57% PEM. We observed overall 30.8% positive SNs in 13 consecutive patients operated for high-risk nonmelanoma skin cancer between 2002 and 2011 in our institution. These high rates support recommendation to implement SLNB for nonmelanoma skin cancer especially for SCC patients. Completion lymph node dissection following positive SNs is also a matter of discussion especially in PEM. It must be remembered that a definitive survival benefit of SLNB in melanoma patients has not been proven yet. However, because of its low morbidity when compared to empiric elective lymph node dissection or radiation therapy of lymphatic basins, SLNB has allowed sparing a lot of morbidity and could therefore be used in nonmelanoma skin cancer patients, even though a significant impact on survival has not been demonstrated.

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.

Spitz nevi and other Spitzoid lesions part II. Natural history and management

For dermatologists, evidence-based management guidelines for Spitz tumors have not been established. Despite the lack of a standardized approach, most dermatologists recommend the excision of Spitz tumors occurring in adults and adopt more conservative measures towards pediatric cases. The histopathologic attributes and the clinical scenario are factored into management in each case. While the metastatic behavior of certain Spitz tumors is well known, the malignant potential of these lesions remains unclear because they only rarely result in negative outcomes. The risks and benefits of adjunctive measures, such as sentinel lymph node biopsy and interferon use, remain untested and are subjects of ongoing controversy. (In part II of this continuing medical education article, we will continue to use the terminology defined in part I for purposes of continuity. "Spitz tumor" is used as the umbrella term for the entire category of lesions, "common Spitz nevi" refers to only the most typical lesions seen in pediatric cases, and "atypical Spitz tumors" encompass the "all other" category, which continues to cause debate.).

Soluble adenylyl cyclase antibody profile as a diagnostic adjunct in the assessment of pigmented lesions

OBJECTIVE

To investigate the usefulness of a novel marker for melanocytic proliferations.

DESIGN

Using a novel monoclonal antibody against soluble adenylyl cyclase (sAC), various benign and malignant melanocytic proliferations were immunostained.

SETTING

Weill Medical College of Cornell University dermatopathology laboratory.

MAIN OUTCOME MEASURES

The results were qualitative, not quantifiable.

RESULTS

The sAC immunostaining produced distinctive patterns that paralleled melanomagenesis. At one pole of the spectrum were benign nevi, including atypical nevi of special sites and recurrent nevi showing a distinct pattern of dotlike Golgi staining, while at the opposite pole was melanoma, in which many cells demonstrated an intense pannuclear expression pattern, often accompanied by loss of the Golgi expression pattern. Melanomas of lentigo maligna and acral lentiginous subtypes exhibited the most striking pannuclear expression, while nodular melanomas showed the least, although with supervening enhanced diffuse cytoplasmic expression. Loss of the Golgi expression pattern was a feature of malignant melanoma.

CONCLUSION

The sAC expression pattern is complex but seems discriminatory, with distinctive and variable staining patterns according to the nature of the lesion biopsied.

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.

Animal-type melanoma - tumor cell invasion of dermal lymphatics and molecular identification of lymph node metastasis

Animal-type melanoma (ATM) represents a rare subtype within the wide spectrum of melanocytic tumors. Clinically, ATM lesions appear as sharply demarcated, brown, black and dark blue pigmented nodules, which show grey-white surface elements on dermatoscopy. The tumor is restricted to the dermis and arranged in irregular fascicles, which are composed of spindle-shaped and epithelioid melanocytes. Moderate tumor cell pleomorphism, mitoses and apoptotic cells all suggest a malignant process. Abundant, finely dispersed melanin pigment within tumor cells as well as numerous melanophages are strongly suggestive of ATM. Even though locoregional lymph node metastases are frequently found at diagnosis, the course of ATM is generally benign. Specific molecular changes may be detected in melanocytes from lesions and lymph nodes on fluorescence in situ hybridization (FISH). Such findings strongly indicate the malignant potential of ATM. The peculiar biology of ATM, as a moderately malignant tumor, is reflected in a new histopathological classification within the spectrum of dermal borderline melanocytic tumors (BMT).