Immunohistochemical characteristics of melanoma

Managing malignant melanoma

The incidence of melanoma is increasing worldwide. Melanomas represent 3 percent of all skin cancers but 65 percent of skin cancer deaths. Melanoma is now the fifth most common cancer diagnosed in the United States. Excisional biopsy should be performed for lesions suspicious for melanoma. The pathologist's report provides essential information for surgical treatment; the most important information is the Breslow depth of the lesion. In addition to wide surgical excision of the primary lesion, sentinel lymph node biopsy is the standard of care for early identification of regional metastasis. Nodal metastasis found in the sentinel lymph node biopsy should be followed with a complete lymph node dissection. Although surgery remains the primary treatment of melanoma, recent advances in chemotherapy may offer further survival benefits to patients with metastatic disease.

Marginal and joint distributions of S100, HMB-45, and Melan-A across a large series of cutaneous melanomas

CONTEXT

The distribution of the standard melanoma antibodies S100, HMB-45, and Melan-A has been extensively studied. Yet, the overlap in their expression is less well characterized.

OBJECTIVES

To determine the joint distributions of the classic melanoma markers and to determine if classification according to joint antigen expression has prognostic relevance.

DESIGN

S100, HMB-45, and Melan-A were assayed by immunofluorescence-based immunohistochemistry on a large tissue microarray of 212 cutaneous melanoma primary tumors and 341 metastases. Positive expression for each antigen required display of immunoreactivity for at least 25% of melanoma cells. Marginal and joint distributions were determined across all markers. Bivariate associations with established clinicopathologic covariates and melanoma-specific survival analyses were conducted.

RESULTS

Of 322 assayable melanomas, 295 (91.6%), 203 (63.0%), and 236 (73.3%) stained with S100, HMB-45, and Melan-A, respectively. Twenty-seven melanomas, representing a diverse set of histopathologic profiles, were S100 negative. Coexpression of all 3 antibodies was observed in 160 melanomas (49.7%). Intensity of endogenous melanin pigment did not confound immunolabeling. Among primary tumors, associations with clinicopathologic parameters revealed a significant relationship only between HMB-45 and microsatellitosis (P = .02). No significant differences among clinicopathologic criteria were observed across the HMB-45/Melan-A joint distribution categories. Neither marginal HMB-45 (P = .56) nor Melan-A (P = .81), or their joint distributions (P = .88), was associated with melanoma-specific survival.

CONCLUSIONS

Comprehensive characterization of the marginal and joint distributions for S100, HMB-45, and Melan-A across a large series of cutaneous melanomas revealed diversity of expression across this group of antigens. However, these immunohistochemically defined subclasses of melanomas do not significantly differ according to clinicopathologic correlates or outcome.

Canine olfactory detection of malignant melanoma

Our patient is a 75-year-old man who presented after his pet dog licked persistently at an asymptomatic lesion behind his right ear. Examination revealed a nodular lesion in the postauricular sulcus. Histology confirmed malignant melanoma, which was subsequently excised. Canine olfactory detection of human malignancy is a well-documented phenomenon. Advanced olfaction is hypothesised to explain canine detection of bladder, breast, colorectal, lung, ovarian, prostate and skin cancers. Further research in this area may facilitate the development of a highly accurate aid to diagnosis for many malignancies, including melanoma.

Cell migration or cytokinesis and proliferation?--revisiting the "go or grow" hypothesis in cancer cells in vitro

The mortality of patients with solid tumors is mostly due to metastasis that relies on the interplay between migration and proliferation. The "go or grow" hypothesis postulates that migration and proliferation spatiotemporally excludes each other. We evaluated this hypothesis on 35 cell lines (12 mesothelioma, 13 melanoma and 10 lung cancer) on both the individual cell and population levels. Following three-day-long videomicroscopy, migration, proliferation and cytokinesis-length were quantified. We found a significantly higher migration in mesothelioma cells compared to melanoma and lung cancer while tumor types did not differ in mean proliferation or duration of cytokinesis. Strikingly, we found in melanoma and lung cancer a significant positive correlation between mean proliferation and migration. Furthermore, non-dividing melanoma and lung cancer cells displayed slower migration. In contrast, in mesothelioma there were no such correlations. Interestingly, negative correlation was found between cytokinesis-length and migration in melanoma. FAK activation was higher in melanoma cells with high motility. We demonstrate that the cancer cells studied do not defer proliferation for migration. Of note, tumor cells from various organ systems may differently regulate migration and proliferation. Furthermore, our data is in line with the observation of pathologists that highly proliferative tumors are often highly invasive.

Differences in tumor thickness between hematoxylin and eosin and Melan-A immunohistochemically stained primary cutaneous melanomas

Tumor thickness (Breslow thickness) represents the main prognostic factor in primary melanoma. Potential differences in melanoma tumor thickness measurements between conventional hematoxylin and eosin (H&E) and Melan-A immunohistochemical staining were evaluated. Ninety-nine excisional biopsies were included in the study. From each sample, 2 consecutive histological sections were stained with H&E and Melan-A, respectively. Tumor thickness was measured from both sections by 2 independent observers. In 59 biopsy specimens (59.6%), higher tumor thickness measurements were recorded in Melan-A-stained than in H&E-stained sections. In 42.4% of such cases (25 biopsies), the observed differences were ≥0.2 mm. After Melan-A evaluation, 33% of in situ melanoma cases were reclassified as invasive melanoma, with thickness measurements ranging from 0.15 to 0.35 mm. In 23 biopsies, identical values were recorded with both techniques, whereas in 17 cases, measurements obtained with H&E staining were slightly higher (from 0.01 to 0.18 mm) than those obtained with Melan-A staining. A high rate of interobserver agreement was noted, and significant intertechnique measurement differences were detected. Significant discrepancies (≥0.2 mm) in thickness measurements between the 2 techniques were mainly attributed to the presence of individual or small clusters of melanocytic cells in the papillary dermis. These melanocytic cells could be easily overlooked in H&E-stained sections, especially in sections showing dense lymphohistiocytic inflammatory infiltrates, numerous melanin-containing histiocytic cells in the upper dermis, or extensive fibrotic changes or regression phenomena. This study confirms the practical interest of immunohistochemical staining with Melan-A in evaluating primary melanoma and, specifically, in situ melanoma cases.

A Melanoma Brain Metastasis with a Donor-Patient Hybrid Genome following Bone Marrow Transplantation: First Evidence for Fusion in Human Cancer

Background

Tumor cell fusion with motile bone marrow-derived cells (BMDCs) has long been posited as a mechanism for cancer metastasis. While there is much support for this from cell culture and animal studies, it has yet to be confirmed in human cancer, as tumor and marrow-derived cells from the same patient cannot be easily distinguished genetically.

Methods

We carried out genotyping of a metastatic melanoma to the brain that arose following allogeneic bone-marrow transplantation (BMT), using forensic short tandem repeat (STR) length-polymorphisms to distinguish donor and patient genomes. Tumor cells were isolated free of leucocytes by laser microdissection, and tumor and pre-transplant blood lymphocyte DNAs were analyzed for donor and patient alleles at 14 autosomal STR loci and the sex chromosomes.

Results

All alleles in the donor and patient pre-BMT lymphocytes were found in tumor cells. The alleles showed disproportionate relative abundances in similar patterns throughout the tumor, indicating the tumor was initiated by a clonal fusion event.

Conclusions

Our results strongly support fusion between a BMDC and a tumor cell playing a role in the origin of this metastasis. Depending on the frequency of such events, the findings could have important implications for understanding the generation of metastases, including the origins of tumor initiating cells and the cancer epigenome.

Neuropathology of brain metastases

Metastatic tumors are the most common neoplasms encountered in the central nervous system (CNS), and continue to be major cause for mortality and morbidity. Macroscopic features and corresponding radiological findings can be diagnostic in majority of the cases, however, microscopic evaluation would be necessary when the differential diagnosis includes a primary CNS tumor, unknown primary tumor site, and when the resection of the tumor is either considered therapeutic or palliative. The first step in the diagnosis of a metastatic brain lesion is to exclude a primary CNS tumor, followed by verification or identification of the primary tumor and the site. Although general approach to a metastatic lesion from an unknown primary tumor is the same everywhere else, there are slight variations for the metastatic lesions in the CNS versus other regions. When morphological features are not enough to establish a definitive diagnosis, additional studies including immunohistochemical stains are applied. With the expending immunohistochemical armamentarium for pathologists, more accurate assessments are possible even in cases of unknown primary tumor. This review summarizes the diagnostic approach to CNS metastases, immunohistochemical assessment of neoplasm of unknown primary, and primary CNS lesions entering in the differential diagnosis of metastases.

Rapidly progressive and fatal neurocutaneous melanosis presenting as recurrent headache

Neurocutaneous melanosis is an extremely rare disease characterized by large or multiple congenital melanocytic nevi and benign or malignant proliferation of melanocytes in the central nervous system. Neurological manifestations usually develop during the first three years of life and the prognosis of patients with NCM who manifest neurological symptoms is very poor. Here we describe a 9-year-old girl who manifested neurological symptoms caused by communicating hydrocephalus and died of proliferation of melanocytes in the central nervous system 11 months after the initial symptoms. Serum and cerebrospinal fluid 5-S-CD levels could be a useful marker of disease progression, even in patients with NCM without apparent malignant findings at initial biopsy.

Immunotherapy in the management of melanoma: current status

As the rate of melanoma continues to increase, so does the need for more effective and durable therapies. Despite considerable research, the management of advanced disease remains challenging. Numerous therapies are being investigated, many of which aim at upregulating the immune system’s innate ability to attack the tumor. Cytotoxic T lymphocyte antigen 4 antibodies are immune stimulants that act as negative regulators of the immune system by modifying an antitumor T-cell response. Ipilimumab, one such cytotoxic T lymphocyte antigen 4 antibody, and vemurafenib, a BRAF competitive inhibitor, were approved as first-line therapies in 2011 due to improved survival rates versus standard chemotherapy. Allovectin-7 is a lipid plasmid that encodes for major histone compatibility complex DNA sequences. It has led to increases in cytotoxic T-cell production, which subsequently attacks the tumor. OncoVEX, an oncolytic herpes virus, and PV-10, a chemoablative agent, have yielded promising results in metastatic lesions and have demonstrated a unique “bystander” phenomenon. In this paper we review the basics of melanoma from the pathophysiology, risk factors, signs, diagnostic approaches, and current status of immunologic management of melanoma.

F-18 fluorodeoxyglucose PET/CT and post hoc PET/MRI in a case of primary meningeal melanomatosis

Primary meningeal melanomatosis is a rare, aggressive variant of primary malignant melanoma of the central nervous system, which arises from melanocytes within the leptomeninges and carries a poor prognosis. We report a case of primary meningeal melanomatosis in a 17-year-old man, which was diagnosed with (18)F-fluorodeoxyglucose (F-18 FDG) PET/CT, and post hoc F-18 FDG PET/MRI fusion images. Whole-body F-18 FDG PET/CT was helpful in ruling out the extracranial origin of melanoma lesions, and in assessing the therapeutic response. Post hoc PET/MRI fusion images facilitated the correlation between PET and MRI images and demonstrated the hypermetabolic lesions more accurately than the unenhanced PET/CT images. Whole body F-18 FDG PET/CT and post hoc PET/MRI images might help clinicians determine the best therapeutic strategy for patients with primary meningeal melanomatosis.

Immunohistochemical Expression of Melanocytic Antigen PNL2, Melan A, S100, and PGP 9.5 in Equine Melanocytic Neoplasms

The immunoreactivity of PNL2, Melan A, and protein gene product (PGP) 9.5 was compared with that of S100 protein in 50 formalin-fixed, paraffin-embedded equine melanocytic neoplasms. PNL2, PGP 9.5, and S100 protein were detected in all 50 neoplasms; none expressed Melan A. PNL2 was not expressed in 62 nonmelanocytic tumors (equine sarcoids, schwannomas, carcinomas, sarcomas, endocrine tumors, sex-cord stromal tumors, germ cell tumors, and leukocytic tumors) or in normal tissues other than epidermis. In summary, antibody PNL2 is a sensitive marker of equine melanocytic neoplasms and is more specific than S100 protein or PGP 9.5. In contrast, the monoclonal antibody to Melan A did not react with any of the equine melanomas.

Immunohistochemical features of multifocal melanoacanthoma in the hard palate: a case report

BACKGROUND

Melanoacanthoma (MA) has been described in the oral mucosa as a solitary lesion or, occasionally, as multiple lesions. MA mainly affects dark skinned patients and grows rapidly, showing a plane or slightly raised appearance and a brown to black color. The differential diagnosis includes oral nevi, amalgam tattoos, and melanomas. We report here the case of a 58-year-old black woman who presented multiple pigmented lesions on the hard palate.

CASE PRESENTATION

Based on the differential diagnosis of melanoma, a punch biopsy (4 mm in diameter) was performed. The material was fixed in 10% formalin, embedded in paraffin, and stained with hematoxylin-eosin or submitted to immunohistochemical analysis. Immunohistochemistry using antibodies against protein S-100, melan-A, HMB-45, MCM-2, MCM-5, Ki-67 and geminin was performed. Immunohistochemical analysis revealed strong cytoplasmic immunoreactivity of dendritic melanocytes for proteinS-100, HMB-45 and melan-A.Positive staining for proliferative markers (MCM-2, MCM-5, Ki-67) was only observed in basal and suprabasal epithelial cells, confirming the reactive etiology of the lesion. The diagnosis was oral Melanoacanthoma (MA).

CONCLUSION

The patient has been followed up for 30 months and shows no clinical alterations. MA should be included in the differential diagnosis of pigmented lesions of the oral cavity.

Diagnostic utility of neural stem and progenitor cell markers nestin and SOX2 in distinguishing nodal melanocytic nevi from metastatic melanomas

Sentinel lymph node evaluation is a critical component of melanoma staging, and lymph node status provides one of the most powerful predictors of melanoma recurrence and survival. One of the well-known diagnostic pitfalls in melanoma sentinel lymph node evaluation is the presence of nodal melanocytic nevi, which has been demonstrated in up to 26% of lymphadenectomy specimens and specifically in melanoma patients. Melanocytic markers enhance the sensitivity of melanoma detection in sentinel lymph nodes. However, established markers such as anti-melan-A/MART1, S100 protein and SOX10 antibodies cannot discriminate melanoma metastasis from nodal nevi. Recent studies have demonstrated strong expression of neural stem/progenitor cell markers nestin and SOX2 in melanoma. In this study, we tested the diagnostic utility of nestin and SOX2 in differentiating metastatic melanomas from nodal nevi. Twenty-three lymph nodes with metastatic melanomas and 17 with nodal nevi were examined. Of the 23 metastatic melanomas, 18 showed diffuse and strong (3+) nestin, 4 showed rare cells with strong (3+) nestin, and one showed diffuse but faint (1+) nestin staining. Nuclear SOX2 was positive in 13 metastatic melanomas. In contrast, 15 nodal nevi showed no nestin, and 2 showed rare cells with very faint (<1+) nestin staining. SOX2 was negative in 13 nodal nevi. Overall, nestin was strongly expressed in metastatic melanomas (n=22/23; 96%), but not in nodal melanocytic nevi (n=15/17; 88%; P<0.0001). SOX2 was also expressed in metastatic melanomas (n=13/23; 57%) but not in the majority of nodal melanocytic nevi (n=13/16; 81%; P=0.02). In one lymph node harboring metastatic melan-A-negative desmoplastic melanoma, nestin and SOX2 strongly highlighted the infiltrating tumor cells, suggesting the potential clinical value of these two markers in desmoplastic melanoma lymph node biopsies. This study provides evidence that nestin and SOX2 can effectively differentiate nodal melanocytic nevi from metastatic melanomas and serve as powerful diagnostic adjuncts in melanoma staging.

Metastatic Melanoma Presenting as an Isolated Breast Tumor: A Study of 20 Cases With Emphasis on Several Primary Mimickers

Context.—The mammary gland can be a site of metastasis in patients with malignant melanoma, which is easily recognized microscopically if clinical information is available. Nonetheless, metastatic melanoma presenting as an isolated mammary tumor can be more challenging to diagnose because it can simulate a primary breast carcinoma clinically and morphologically.

Objective.—To review metastatic melanoma to the breast, presenting as primary breast carcinomas clinically and morphologically.

Design.—The authors report 20 cases of metastatic melanoma clinically presenting as breast tumors. Cases with widespread metastatic presentation were excluded.

Results.—Epithelioid and spindle cell tumors predominated, suggesting mammary ductal, papillary, or sarcomatoid carcinoma. Most cases (16 of 20) were submitted for consultation or second opinion owing to their unusual presentation in the breast, or to perform predictive/prognostic immunohistochemical assays. Seven cases had a remarkable phenotypic spectrum expanding the differential diagnosis to large cell lymphoma, leiomyosarcoma, medullary carcinoma, malignant schwannoma, and liposarcoma. Tumor cells were negative for cytokeratin stains and positive for S100 protein, HMB-45, and Melan-A. Negative staining was also observed for epithelial membrane antigen, CD45, desmin, estrogen and progesterone receptors, and human epidermal growth factor receptor 2.

Conclusions.—Metastatic melanoma may simulate a broad spectrum of primary breast malignancies. Although the application of a simple panel of antibodies assists in rendering the correct interpretation, lesions presenting as isolated breast tumors may introduce a significant diagnostic difficulty, especially when there is inadequate patient history and/or limited biopsy material. Further challenges are introduced by the extraordinary phenotypic plasticity of metastatic melanoma. Awareness of this pattern variance is essential to avoid inappropriate treatment, especially in cases simulating a “triple negative,” poorly differentiated carcinoma of the breast.

Collagen XVII is expressed in malignant but not in benign melanocytic tumors and it can mediate antibody induced melanoma apoptosis

The 180 kDa transmembrane collagen XVII is known to anchor undifferentiated keratinocytes to the basement membrane in hemidesmosomes while constitutively shedding a 120 kDa ectodomain. Inherited mutations or auto-antibodies targeting collagen XVII cause blistering skin disease. Collagen XVII is down-regulated in mature keratinocytes but re-expressed in skin cancer. By recently detecting collagen XVII in melanocyte hyperplasia, here we tested its expression in benign and malignant melanocytic tumors using endodomain and ectodomain selective antibodies. We found the full-length collagen XVII protein in proliferating tissue melanocytes, basal keratinocytes and squamous cell carcinoma whereas resting melanocytes were negative. Furthermore, the cell-residual 60 kDa endodomain was exclusively detected in 62/79 primary and 15/18 metastatic melanomas, 8/9 melanoma cell lines, HT199 metastatic melanoma xenografts and atypical nests in 8/63 dysplastic nevi. The rest of 19 nevi including common, blue and Spitz subtypes were also negative. In line with the defective ectodomain, sequencing of COL17A1 gene revealed aberrations in the ectodomain coding region including point mutations. Collagen XVII immunoreaction-stained spindle cell melanomas, showed partly overlapping profiles with those of S100B, Melan A and HMB45. It was concentrated at vertical melanoma fronts and statistically associated with invasive phenotype. Antibody targeting the extracellular aa507-529 terminus of collagen XVII endodomain promoted apoptosis and cell adhesion, while inhibiting proliferation in HT199 cells. These results suggest that the accumulation of collagen XVII endodomain in melanocytic tumors is associated with malignant transformation to be a potential marker of malignancy and a target for antibody-induced melanoma apoptosis.

Novel multiple markers to distinguish melanoma from dysplastic nevi

Background

Distinguishing melanoma from dysplastic nevi can be challenging.

Objective

To assess which putative molecular biomarkers can be optimally combined to aid in the clinical diagnosis of melanoma from dysplastic nevi.

Methods

Immunohistochemical expressions of 12 promising biomarkers (pAkt, Bim, BRG1, BRMS1, CTHRC1, Cul1, ING4, MCL1, NQO1, SKP2, SNF5 and SOX4) were studied in 122 melanomas and 33 dysplastic nevi on tissue microarrays. The expression difference between melanoma and dysplastic nevi was performed by univariate and multiple logistic regression analysis, diagnostic accuracy of single marker and optimal combinations were performed by receiver operating characteristic (ROC) curve and artificial neural network (ANN) analysis. Classification and regression tree (CART) was used to examine markers simultaneous optimizing the accuracy of melanoma. Ten-fold cross-validation was analyzed for estimating generalization error for classification.

Results

Four (Bim, BRG1, Cul1 and ING4) of 12 markers were significantly differentially expressed in melanoma compared with dysplastic nevi by both univariate and multiple logistic regression analysis (p < 0.01). These four combined markers achieved 94.3% sensitivity, 81.8% specificity and attained 84.3% area under the ROC curve (AUC) and the ANN classified accuracy with training of 83.2% and testing of 81.2% for distinguishing melanoma from dysplastic nevi. The classification trees identified ING4, Cul1 and BRG1 were the most important classification parameters in ranking top-performing biomarkers with cross-validation error of 0.03.

Conclusions

The multiple biomarkers ING4, Cul1, BRG1 and Bim described here can aid in the discrimination of melanoma from dysplastic nevi and provide a new insight to help clinicians recognize melanoma.

MDM4 is a key therapeutic target in cutaneous melanoma

The inactivation of the p53 tumor suppressor pathway, which often occurs through mutations in TP53 (encoding tumor protein 53) is a common step in human cancer. However, in melanoma-a highly chemotherapy-resistant disease-TP53 mutations are rare, raising the possibility that this cancer uses alternative ways to overcome p53-mediated tumor suppression. Here we show that Mdm4 p53 binding protein homolog (MDM4), a negative regulator of p53, is upregulated in a substantial proportion (∼65%) of stage I-IV human melanomas and that melanocyte-specific Mdm4 overexpression enhanced tumorigenesis in a mouse model of melanoma induced by the oncogene Nras. MDM4 promotes the survival of human metastatic melanoma by antagonizing p53 proapoptotic function. Notably, inhibition of the MDM4-p53 interaction restored p53 function in melanoma cells, resulting in increased sensitivity to cytotoxic chemotherapy and to inhibitors of the BRAF (V600E) oncogene. Our results identify MDM4 as a key determinant of impaired p53 function in human melanoma and designate MDM4 as a promising target for antimelanoma combination therapy.

Malignant melanoma and its stromal nonimmune microecosystem

In recent years, rapid advances were reached in the understanding of a series of biologic signals influencing cutaneous malignant melanoma (CMM) cells. CMM is in close contact with a peculiar dermal extracellular matrix (ECM). Stromal cells store and release various structural ECM components. The impact on CMM growth and progression is mediated through strong and long-lasting effects of ECM products. This paper summarizes some peculiar aspects of the peri-CMM stroma showing intracytoplasmic loads in Factor XIIIa, CD34, versican, and α (IV) collagen chains. The restricted peri-CMM skin territory exhibiting such changes corresponds to the area showing neoangiogenesis and extravascular unicellular metastatic spread. The latter inconspicuous migratory CMM cells possibly correspond to CMM stem cells or to CMM cells with aberrant HOX gene expression. Their presence is associated with an increased risk for metastases in the regional sentinel lymph nodes. In conclusion, the CMM-stroma connection appears crucial to the growth regulation, invasiveness and initial metastatic spread of CMM cells. Although much remains to be learned in this field, the active intervention of the peri-CMM stroma is likely involved in the inconspicuous early metastatic migration of CMM cells.

The pathology of melanoma

Although melanoma represents only 10% of all skin cancer diagnoses, it accounts for at least 65% of all skin cancer-related deaths. The number of new cutaneous melanoma cases projected during 2010 was 68,000-a 23% increase from the 2004 prediction of 55,100 cases. In 2015, the lifetime risk of developing melanoma is estimated to increase to 1 in 50. As the incidence of melanoma continues to rise, now more than ever, clinicians and histopathologists must have familiarity with the various clinical and pathologic features of cutaneous melanoma.

Automated Quantification of MART1-Verified Ki67 Indices by Digital Image Analysis in Melanocytic Lesions

Context.—The proliferation marker Ki67 is an important diagnostic and prognostic aid in surgical pathology. However, manual quantification in a counting frame to accurately establish the proliferation rate (Ki67 index) is cumbersome and time-consuming. Instead, digital image analysis of Ki67/MART1 double stains may provide fast and novel index computations for entire tumor sections.

Objectives.—To design and compare image analysis protocols that compute Ki67 indices of Ki67/MART1 double stains, to compare automated indices with previously published manual indices, and to compare the total number of proliferating cells (mimicking a Ki67 single stain) with the number of MART1-verified proliferating cells.

Design.—Whole slide images were captured from 48 melanomas and 77 nevi stained with an immunohistochemical cocktail against Ki67 and MART1. Ki67 indices were determined by digital image analysis and different equations based on number or area.

Results.—The differences between mean indices of melanomas and nevi were significant (P &lt; .001) in all index computations. Number-based image analysis of lesions with more than 250 melanocytic cells misclassified 1 of 42 melanomas and 4 of 53 nevi, numbers comparable with manual counting. Automated indices were significantly higher than manual indices, as were indices of mimicked Ki67 single stains compared with MART1-verified Ki67 indices (P &lt; .001).

Conclusions.—Ki67 indices established by digital image analysis of Ki67/MART1 double stains demonstrated excellent abilities to discriminate melanomas from nevi with diagnostic performances equal to manually performed indices. Testing different definitions of the automated MART1-verified Ki67 index, no single definition stood out; thus, a variety of definitions may be used.

Primary oral melanoma: a histopathological and immunohistochemical study of 22 cases of Latin America

OBJECTIVE

The aim of this study was to analyze the histopathological and immunohistochemical characteristics of 22 cases of primary oral melanomas (OM).

STUDY DESIGN

Twenty two cases of primary oral melanoma were analyzed by description of their histopathological features and immunohistochemical study using the antibodies S-100, HMB-45, Melan-A and Ki-67.

RESULTS

The mean age was 58 years and 14 cases were female. The main affected sites were the hard palate, followed by the upper gingiva. Microscopically, 15 cases presented level III of invasion, 2 cases were amelanotic and 13 showed a mixed epithelioid and plasmacytoid or spindle cells composition. Some cases showed necrosis, perivascular and perineural invasion. S-100 and HMB-45 were positive in all cases, but 3 cases were negative for Melan-A. The proliferative index with Ki-67 was high, with labeling index ranging from 15.51% to 63% of positive cells.

CONCLUSION

S-100 and HMB-45 are more frequently expressed than Melan-A in primary oral melanomas and these markers are helpful to confirm the diagnosis.

Melanoma amelanótico em cães: estudo retrospectivo de 35 casos (2004-2010) e caracterização imuno-histoquímica

Melanomas são tumores agressivos de melanócitos que ocorrem principalmente na cavidade oral, nas junções mucocutâneas e na pele de cães. Este tipo de neoplasma pode apresentar diversos graus de pigmentação melânica, incluindo total ausência (melanomas amelanóticos [MA]). Os arquivos de biópsia do SPV-UFRGS, que compreendem o período de 2004 a 2010, foram revisados e levantados os casos de neoplasias melanocíticas em cães. Realizou-se estudo retrospectivo de 35 casos de MA e caracterização pela imuno-histoquímica (IHQ). As principais raças acometidas foram o Poodle, Dachshund e Cocker Spaniel, mas o maior número de casos foi observado em cães sem raça definida (SRD). A idade média desses cães foi de 10,7 anos (variação de 5 a 18 anos) e não houve predileção por sexo. As principais localizações incluíram cavidade oral (57,1%) e dígitos (17,1%). Histologicamente, 40% dos MA foram classificados como epitelioides, 34,3% como mistos e 25,7% como fusiformes. Na avaliação IHQ, 86,6% dos casos foram positivos para a vimentina, 70% para a proteína S-100 e 56,6% para o melan-A. Os resultados obtidos neste trabalho possibilitam concluir que os cães com MA caracterizavam-se por serem velhos. A forma celular mais observada foi a epitelioide. Devido a pouca diferenciação desses tumores, ressalta-se a importância da realização do painel imuno-histoquímico, sobretudo da proteína S-100, que apresentou melhor marcação que o melan-A.

Primary nasal mucosal melanoma in Brazil: clinicopathologic and immunohistochemical study of 12 patients

Primary nasal melanoma is a rare tumor of unknown etiopathogenesis that occurs in adult and elderly patients usually diagnosed at advanced stages. The aim of this study was to analyze the clinicopathologic and immunohistochemical characteristics of 12 cases of primary nasal melanomas in Brazil. Twelve cases of primary nasal melanoma were analyzed histologically and by immunohistochemistry using the antibodies S-100 protein, HMB-45, Melan-A, CD63 (NKI/C3), CD68/KP1, fatty acid synthase (FASN), and Ki-67. The mean age of the patients was 60 years, and 7 of 12 patients were men. Microscopically, 10 cases presented level III of invasion; 4 were amelanotic; and in 7, cells were epithelioid. S-100 protein and FASN were positive in all cases, whereas 9, 8, 7, and 6 cases were positive for HMB-45, Melan-A, CD63 (NKI/C3), and CD68/KP1, respectively. Ki-67 labeling index ranged from 11.45% to 28.5% of positive cells. S-100 protein is more frequently expressed in nasal melanomas than in HMB-45, Melan-A, CD63 (NKI/C3), and CD68/KP1. FASN seems to be involved in the pathogenesis of nasal melanomas, and also, it can be helpful to confirm the diagnosis.

Host-derived pericytes and Sca-1+ cells predominate in the MART-1- stroma fraction of experimentally induced melanoma

Identification of cell types in tumor-associated stroma that are involved in the development of melanoma is hampered by their heterogeneity. The authors used flow cytometry and immunohistochemistry to demonstrate that anti-MART-1 antibodies can discriminate between melanoma and stroma cells. They investigated the cellular composition of the MART-1-, non-hematopoietic melanoma-associated stroma, finding it consisted mainly of Sca-1+ and CD146+ cells. These cell types were also observed in the skin and muscle adjacent to developing melanomas. The Sca-1+ cell population was observed distributed in the epidermis, hair follicle bulges, and tumor capsule. The CD146+ population was found distributed within the tumor, mainly associated with blood vessels in a perivascular location. In addition to a perivascular distribution, CD146+ cells expressed α-smooth muscle actin, lacked expression of endothelial markers CD31 and CD34, and were therefore identified as pericytes. Pericytes were found to be associated with CD31+ endothelial cells; however, some pericytes were also observed associated with CD31-, MART-1+ B16 melanoma cells that appeared to form blood vessel structures. Furthermore, the authors observed extensive nuclear expression of HIF-1α in melanoma and stroma cells, suggesting hypoxia is an important factor associated with the melanoma microenvironment and vascularization. The results suggest that pericytes and Sca-1+ stroma cells are important contributors to melanoma development.

Tissue microarray analysis of ezrin, KBA.62, CD166, nestin, and p-Akt in melanoma versus banal and atypical nevi, and nonmelanocytic lesions

Multiple melanocytic markers are useful for differentiating between melanoma and nonmelanocytic lesions but generally do not distinguish melanoma from nevi and atypical melanocytic lesions. We sought to determine if several immunohistochemical markers recently described in the literature, including ezrin, KBA.62, p-Akt, CD166, and nestin, may be helpful in distinguishing these lesions. One hundred ten tissue microarray samples were scored for nestin and CD166 and 220 samples for ezrin, KBA.62, and p-Akt. We found that putative stem cell markers nestin and CD166 were both expressed in most melanomas (86% and 65% of samples, respectively), including desmoplastic melanoma, but were also expressed at similar levels in nevi (79% and 74%, respectively). In addition, these markers were not specific for melanocytic lesions. Ezrin was also expressed in both nevi and melanoma (81% each), including desmoplastic melanoma (75%), and in neural tumors. KBA.62 stained more cases of nevi versus melanoma (93% and 65%, respectively) and was positive in 53% of desmoplastic melanoma. However, it was also positive in several nonmelanocytic tumors. P-Akt expression was generally weak but was increased in nevi (75%) versus melanoma (43%), and was lost in desmoplastic melanomas (5%). Overall, only KBA.62 and p-Akt expression differed between melanoma and nevi, and none of these markers were completely specific for melanocytic tumors versus nonmelanocytic lesions.

Cell proliferation in cutaneous malignant melanoma: relationship with neoplastic progression

The establishment of the diagnosis of cutaneous malignant melanoma (CMM) always calls for histopathological confirmation. Further to the recognition of the CMM aspects, immunohistochemistry is helpful, in particular, in determining the size of the replicative compartment and the activity in each of the cell cycle phases (G(1), S, G(2), M). The involvement of cancer stem cells and transient amplifier cells in CMM genesis is beyond doubt. The proliferation activity is indicative of the neoplastic progression and is often related to the clinical growth rate of the neoplasm. It allows to distinguish high-risk CMM commonly showing a high growth rate, from those CMMs of lower malignancy associated with a more limited growth rate. The recruitment and progression of CMM cells in the cell cycle of proliferation depend on mitogen-activated protein kinase (MAPK) pathway and result from a loss of control normally involving a series of key regulatory cyclins. In addition, the apoptotic pathways potentially counteracting any excess in proliferative activity are out of the dependency of specific regulatory molecular mechanisms. Key molecular components involved in the deregulation of the growth fraction, the cell cycle phases of proliferation, and apoptosis are presently described in CMM.

Thigmotropism of malignant melanoma cells

During malignant melanoma (MM) progression including incipient metastasis, neoplastic cells follow some specific migration paths inside the skin. In particular, they progress along the dermoepidermal basement membrane, the hair follicles, the sweat gland apparatus, nerves, and the near perivascular space. These features evoke the thigmotropism phenomenon defined as a contact-sensing growth of cells. This process is likely connected to modulation in cell tensegrity (control of the cell shape). These specifically located paucicellular aggregates of MM cells do not appear to be involved in the tumorigenic growth phase, but rather they participate in the so-called "accretive" growth model. These MM cell collections are often part of the primary neoplasm, but they may, however, correspond to MM micrometastases and predict further local overt metastasis spread.

Primary cilium depletion typifies cutaneous melanoma in situ and malignant melanoma

Cutaneous melanoma is a lethal malignancy that arises spontaneously or via in situ precursor neoplasms. While melanoma in situ and locally invasive malignant melanoma can be cured surgically, these lesions can sometimes be difficult to distinguish from melanocytic nevi. Thus, the identification of histolopathologic or molecular features that distinguish these biologically distinct lesions would represent an important advance. To this end, we determined the abundance of melanocytic primary cilia in a series of 62 cases composed of typical cutaneous melanocytic nevi, melanoma in situ, invasive melanoma, and metastatic melanoma. Primary cilia are sensory organelles that modulate developmental and adaptive signaling and notably, are substantially depleted from the neoplastic epithelium of pancreatic carcinoma at a stage equivalent to melanoma in situ. In this series, we find that while nearly all melanocytes in 22 melanocytic nevi possessed a primary cilium, a near-complete loss of this organelle was observed in 16 cases of melanoma in situ, in 16 unequivocal primary invasive melanomas, and in 8 metastatic tumors, each associated with a cutaneous primary lesion. These findings suggest that the primary cilium may be used to segregate cutaneous invasive melanoma and melanoma in situ from melanocytic nevi. Moreover, they place the loss of an organelle known to regulate oncogenic signaling at an early stage of melanoma development.

Differential expression patterns of capping protein, protein phosphatase 1, and casein kinase 1 may serve as diagnostic markers for malignant melanoma

Early and accurate diagnosis of malignant melanoma is critical for patient survival. However, currently used diagnostic markers are insufficiently specific, which limits their utility. We aimed to identify molecular markers that are more specific to malignant melanoma, thereby aiding in melanoma diagnosis and treatment. A PCR-based suppression subtractive hybridization was used to identify capping protein Z-line α1, protein phosphatase 1 catalytic subunit β isoform (PP1CB), and casein kinase 1 α1 (CSNK1A1) as being differentially expressed between melanoma cells and normal melanocytes. Quantitative reverse transcription-PCR and western blot analysis confirmed that these genes were overexpressed in melanoma cells. In addition, immunohistochemical assays revealed that the expression of PP1CB and CSNK1A1 was significantly greater in human melanoma specimens than nevi (P<0.0001). Combined application of PP1CB and CSNK1A showed high sensitivity and specificity for melanoma. Thus, our data suggest that PP1CB and CSNK1A1 are potential biomarkers for distinguishing malignant melanoma from other melanocytic lesions. In addition, because capping protein Z-line α1, PP1CB, and CSNK1A1 are involved in cell motility, which underlies invasion and metastasis of human cancer; they may be novel targets for antimetastatic therapies as well.

Identification of nodal metastases in melanoma using sox-10

The presence of S100-positive dendritic cells hinders the identification of isolated melanoma tumor cells and micrometastases in sentinel lymph nodes. Sox-10, a transcription factor that plays an important role in schwannian and melanocytic cell development, is not expressed in dendritic cells. We investigated the diagnostic utility of Sox-10 in the identification of metastases in sentinel and nonsentinel lymph nodes for melanoma. We examined the expression pattern of Sox-10, as compared with S100, Melan-A, and HMB-45 in 93 lymph nodes (40 originally reported as positive and 53 originally reported as negative for metastasis) from 33 sentinel lymph node biopsies and regional lymphadenectomies. Sox-10 and S100 both highlighted metastases in 43 of 43 (100%) positive lymph nodes identified in this study; however, Sox-10 immunohistochemical staining significantly improved the detection of nodal metastases. The nuclear staining of Sox-10 promoted improved distinction between heavily pigmented melanophages and melanocytic metastases in 3 positive lymph nodes. In 2 lymph nodes, Sox-10 was critical in distinguishing S100-positive atypical nodal dendritic cells from tumor cells. Also, Sox-10 significantly improved the identification of micrometastases and isolated tumor cells as compared with S100 in 10 positive lymph nodes. Most importantly, Sox-10 identified micrometastases in 2 lymph nodes, originally reported as negative on S100, Melan-A, and HMB-45 immunostains. Therefore, Sox-10 is a comparable marker to S100 in identifying nodal metastases in melanoma and is especially useful in the setting of lymph nodes with heavily pigmented metastases, numerous S100-positive nodal dendritic cells, micrometastases, and isolated tumor cells.

Molecular dermatopathology in malignant melanoma

At present, immunohistochemistry is taken for granted in the establishment of malignant melanoma (MM) diagnosis. In recent years, molecular diagnosis in dermatopathology has benefited from a vast array of advances in the fields of genomics and proteomics. Sensitive techniques are available for detecting specific DNA and RNA sequences by molecular hybridization. This paper intends to update methods of molecular cytogenetics available as diagnostic adjuncts in the field of MM. Cytogenetics has highlighted the pathogenesis of atypical melanocytic neoplasms with emphasis on the activation of the mitogen-activated protein kinase (MAPK) signalling pathway during the initiation step of the neoplasms. 20 to 40% of MM families have mutations in the tumour suppressor gene p16 or CDKN2A. In addition, somatic mutations in p16, p53, BRAF, and cKIT are present in MM. Genome-wide scan analyses on MM indicate positive associations for genes involved in melanocytic naevi, but MM is likely caused by a variety of common low-penetrance genes. Molecular dermatopathology is expanding, and its use in the assessment of melanocytic neoplasms appears to be promising in the fields of research and diagnosis. Molecular dermatopathology will probably make its way to an increased number of diagnostic laboratories. The expected benefit should improve the patient management. This evolution points to a need for evolution in the training requirements and role of dermatopathologists.

Metastatic melanoma with striking adenocarcinomatous differentiation illustrating phenotypic plasticity in melanoma

We report on the highly unusual case of a 75-year-old woman who developed a biphasic right axillary mass of apparent melanoma and adenocarcinoma 13 years after a diagnosis of primary melanoma on her right upper back. The differential diagnosis included a collision tumor and metastatic melanoma with adenocarcinomatous transdifferentiation. We utilized immunohistochemical staining, DNA sequencing, and comparative genomic hybridization (CGH) to characterize this unusual tumor. By immunohistochemistry, the melanomatous component was positive for S100 and Melan-A, and had patchy positivity for cytokeratin. The adenocarcinomatous component was negative for melanoma markers, but was strongly positive for cytokeratin. In addition, the glandular component was positive for CDX-2 and Ber-EP4, giving the distinct histologic and immunohistochemical impression of a gastrointestinal metastasis nested within a deposit of metastatic melanoma. Clinical and radiologic workup failed to reveal a primary gastrointestinal malignancy. Molecular genetic analysis, including DNA sequencing and CGH, revealed that both areas contained an identical NRAS Q61K mutation and had highly similar CGH profiles, including gains of chromosome 1q and losses of 1p, 4, 9, and 10, which are archetypical of melanoma. The NRAS mutation was also identified in a deposit of metastatic melanoma resected 12 years earlier, but was not seen in the patient's nontumorous tissue, indicating that it was somatically acquired. Genetic analyses demonstrate that 2 morphologically distinct tumors arose from a common ancestor melanoma cell that harbored an NRAS mutation and subsequently divergently evolved by the acquisition of additional genomic alterations. Our findings illustrate the ability of molecular analyses to resolve lineage in complex neoplasms and illustrate the phenotypic plasticity of cancer cells.

Melanoma update: diagnostic and prognostic factors that can effectively shape and personalize management

Routine light microscopy remains a powerful tool to diagnose, stage and prognose melanoma. Although it is very economical and efficient, it requires a significant level of expertise and, in difficult cases the final diagnosis is affected by subjective interpretation. Fortunately, new insights into the genomic aberrations characteristic of melanoma, coupled with ancillary studies, are further refining evaluation and management allowing for more confident diagnosis, more accurate staging and the selection of targeted therapy. In this article, we review the standard of care and new updates including four probe FISH, the 2009 American Joint Commission on Cancer staging of melanoma and mutant testing of melanoma, which will be crucial for targeted therapy of metastatic melanoma.

Immunohistochemical double stains against Ki67/MART1 and HMB45/MITF: promising diagnostic tools in melanocytic lesions

Distinction between benign and malignant melanocytic lesions may be difficult by today's methods, even for highly skilled dermatopathologists, emphasizing the need for improved diagnostic tools. We have studied the discriminative abilities of immunohistochemical (IHC) double stains using the IHC markers Ki67 combined with MART1, and HMB45 combined with MITF. Paraffin-embedded tissue sections from 50 melanomas and 78 benign nevi were stained using a simple simultaneous IHC double staining technique. Both simple semiquantitative estimates of the immunopositivity in the deepest third of the lesions and full-scale quantitative measurements of the Ki67 and HMB45 indices were performed, and scores for melanomas and nevi were compared. The differences between melanomas and nevi were significant (P < 0.0001) using either analysis or stain. The misclassification rates for melanomas and nevi were generally lower for Ki67/MART1 stains than for HMB45/MITF stains. In the simple semiquantitative Ki67/MART1 analysis, the misclassification rates were 6% (2%-17%) for melanomas and 12% (6%-21%) for nevi. In full-scale quantitative analysis the corresponding rates were 4% (1%-14%) and 8% (4%-16%), and by combining Ki67 and HMB45 indices, the misclassification rates were 0% (0%-7%) for melanomas and 13% (7%-22%) for nevi. We conclude that both semiscale and fullscale quantitative analyses of Ki67/MART1 stains are valuable diagnostic tools to distinguish melanomas and nevi with a large degree of certainty. The HMB45/MITF stains may serve as adjuncts to predict malignancy and the diagnostic potential of combining the HMB45 and Ki67 indices are promising. The IHC double stains may potentially reduce misinterpretations of melanomas in histopathology.

Melanophoromas and iridophoromas in reptiles

Chromatophoromas are tumours of pigment-producing cells of the skin and are rarely reported in reptiles. These tumours are subclassified on the basis of the type of pigment. The present study characterizes chromatophoromas arising in 26 reptiles, including six snakes, 19 lizards and a tortoise. These include the first reports of melanophoromas in a yellow anaconda (Eunectes notaeus), pigmy rattlesnake (Sistrurus spp.), southern water snake (Nerodia fasciata), veiled chameleon (Chamaeleo calyptratus) and leopard gecko (Eublepharis macularius); the first reports of benign iridophoromas in a savannah monitor (Varanus exanthematicus), veiled chameleon and bearded dragon (Pogona vitticeps); and the first description of a malignant iridophoroma in a bearded dragon. Additionally, in three bearded dragons a 'mucinous' type of melanophoroma is described for the first time. Chromatophoromas generally arose from the skin of the body and head and ranged in size from 0.2 to 2.0cm in diameter. In six cases the animals were humanely destroyed immediately after diagnosis. Three further animals were humanely destroyed following recurrence of their tumour. Six of these nine reptiles had visceral metastases. Grossly, melanophoromas (n=20) were grey or black, while iridophoromas (n=6) were white in colour. Microscopically, most of the tumours were composed of spindle cells with varying pigmentation and 0-2 mitoses per 10 high power fields. Six of the 20 melanophoromas were classified as malignant due to the presence of intravascular tumour cells, visceral metastases, high pleomorphism and/or mitotic figures. Five of the six iridophoromas were classified as benign and the one malignant tumour was defined by the presence of intravascular tumour cells and visceral metastases. Immunohistochemically, melan A and S100 were coexpressed by all of the chromatophoromas.

Evaluation of multiple serum markers in advanced melanoma

The aim of this retrospective study was to analyse in advanced melanoma the potential tumor markers S-100B, melanoma inhibiting activity protein (MIA) and YKL-40 compared to LDH. Serum levels of S-100B, MIA, LDH and YKL-40 were measured in 110 patients with advanced melanoma (36 in stage IIIB/C and 74 in stage IV), in 66 disease-free patients and in 65 healthy controls. Results show that S-100B, MIA and LDH levels were significantly higher in patients with advanced melanoma than in disease-free patients or healthy controls. The combination of S-100B plus MIA had the best diagnostic sensitivity, and the addition of LDH did not further increase this sensitivity. MIA was an independent prognostic factor of overall survival. Patients with both S-100B and MIA elevated had a significant shorter survival than those with both S-100B and MIA under the cut-off. YKL-40 levels did not differentiate patients with advanced melanoma from controls. We concluded that the combination of MIA plus S-100B showed a better prognostic value in advanced melanoma compared to LDH.