Immunohistochemistry in melanocytic proliferative lesions

Automated diagnosis of 7 canine skin tumors using machine learning on H&E-stained whole slide images

Microscopic evaluation of hematoxylin and eosin-stained slides is still the diagnostic gold standard for a variety of diseases, including neoplasms. Nevertheless, intra- and interrater variability are well documented among pathologists. So far, computer assistance via automated image analysis has shown potential to support pathologists in improving accuracy and reproducibility of quantitative tasks. In this proof of principle study, we describe a machine-learning-based algorithm for the automated diagnosis of 7 of the most common canine skin tumors: trichoblastoma, squamous cell carcinoma, peripheral nerve sheath tumor, melanoma, histiocytoma, mast cell tumor, and plasmacytoma. We selected, digitized, and annotated 350 hematoxylin and eosin-stained slides (50 per tumor type) to create a database divided into training, n = 245 whole-slide images (WSIs), validation (n = 35 WSIs), and test sets (n = 70 WSIs). Full annotations included the 7 tumor classes and 6 normal skin structures. The data set was used to train a convolutional neural network (CNN) for the automatic segmentation of tumor and nontumor classes. Subsequently, the detected tumor regions were classified patch-wise into 1 of the 7 tumor classes. A majority of patches-approach led to a tumor classification accuracy of the network on the slide-level of 95% (133/140 WSIs), with a patch-level precision of 85%. The same 140 WSIs were provided to 6 experienced pathologists for diagnosis, who achieved a similar slide-level accuracy of 98% (137/140 correct majority votes). Our results highlight the feasibility of artificial intelligence-based methods as a support tool in diagnostic oncologic pathology with future applications in other species and tumor types.

ROS Pleiotropy in Melanoma and Local Therapy with Physical Modalities

Metabolic energy production naturally generates unwanted products such as reactive oxygen species (ROS), causing oxidative damage. Oxidative damage has been linked to several pathologies, including diabetes, premature aging, neurodegenerative diseases, and cancer. ROS were therefore originally anticipated as an imperative evil, a product of an imperfect system. More recently, however, the role of ROS in signaling and tumor treatment is increasingly acknowledged. This review addresses the main types, sources, and pathways of ROS in melanoma by linking their pleiotropic roles in antioxidant and oxidant regulation, hypoxia, metabolism, and cell death. In addition, the implications of ROS in various physical therapy modalities targeting melanoma, such as radiotherapy, electrochemotherapy, hyperthermia, photodynamic therapy, and medical gas plasma, are also discussed. By including ROS in the main picture of melanoma skin cancer and as an integral part of cancer therapies, a greater understanding of melanoma cell biology is presented, which ultimately may elucidate additional clues on targeting therapy resistance of this most deadly form of skin cancer.

KIT Expression Is Regulated by DNA Methylation in Uveal Melanoma Tumors

Uveal melanoma (UM) is an ocular tumor with a dismal prognosis. Despite the availability of precise molecular and cytogenetic techniques, clinicopathologic features with limited accuracy are widely used to predict metastatic potential. In 51 UM tissues, we assessed a correlation between the expression of nine proteins evaluated by immunohistochemistry (IHC) (Melan-A, S100, HMB45, Cyclin D1, Ki-67, p53, KIT, BCL2, and AIFM1) and the presence of UM-specific chromosomal rearrangements measured by multiplex ligation-dependent probe amplification (MLPA), to find IHC markers with increased prognostic information. Furthermore, mRNA expression and DNA methylation values were extracted from the whole-genome data, achieved by analyzing 22 fresh frozen UM tissues. KIT positivity was associated with monosomy 3, increasing the risk of poor prognosis more than 17-fold (95% CI 1.53–198.69, p = 0.021). A strong negative correlation was identified between mRNA expression and DNA methylation values for 12 of 20 analyzed positions, five located in regulatory regions of the KIT gene (r = −0.658, p = 0.001; r = −0.662, p = 0.001; r = −0.816; p < 0.001; r = −0.689, p = 0.001; r = −0.809, p < 0.001, respectively). DNA methylation β values were also inversely associated with KIT protein expression (p = 0.001; p = 0.001; p = 0.015; p = 0.025; p = 0.002). Our findings, showing epigenetic deregulation of KIT expression, may contribute to understanding the past failure to therapeutically target KIT in UM.

Micro-environmental cross-talk in an organotypic human melanoma-in-skin model directs M2-like monocyte differentiation via IL-10

Preclinical assessment of novel therapies to fight cancer requires models that reflect the human physiology and immune response. Here, we established an in vitro three-dimensional (3D) reconstructed organotypic human melanoma-in-skin (Mel-RhS) model to investigate cellular and molecular features of tumor formation over a period of 6 weeks. Tumor nests developed over time at the epidermal-dermal junction and spread towards the dermis, in places disrupting the basement membrane. This coincided with secretion of matrix metalloproteinase 9 (MMP-9) by melanoma cells. These features resemble the initial stages of invasive melanoma. Interestingly, while the SK-MEL-28 cell line did not secrete detectable levels of interleukin-10 (IL-10) in traditional two-dimensional monolayers, it did express IL-10 in the 3D Mel-RhS, as did the surrounding keratinocytes and fibroblasts. This cellular cross-talk-induced secretion of IL-10 in the Mel-RhS indicated the generation of an immune suppressive microenvironment. Culture supernatants from Mel-RhS interfered with monocyte-to-dendritic-cell differentiation, leading to the development of M2-like macrophages, which was in part prevented by antibody-mediated IL-10 blockade. Indeed, high-dimensional single-cell analysis revealed a shift within the monocyte population away from a CD163+PD-L1+ M2-like phenotype upon IL-10 blockade. Thus, the 3D configuration of the Mel-RhS model revealed a role for IL-10 in immune escape through misdirected myeloid differentiation, which would have been missed in classical monolayer cultures.

The color of skin: black diseases of the skin, nails, and mucosa

Gradations in skin color are a consequence of differing amounts of melanin and their varying distribution. Although many darkly pigmented skin lesions are melanocytic and can be attributed to melanin content, the color of a black lesion can also be due to blood, necrotic tissue, or exogenous pigment. The source, pattern, and distribution of the color in black lesions usually offer important insight into its etiology. This contribution reviews conditions that can take on a black color, discussing the cause of the hue and any additional impact sun exposure may have.

Identification of melanoma cells and lymphocyte subpopulations in lymph node metastases by FTIR imaging histopathology

While early stages of melanoma are usually cured by surgery, metastatic melanomas are difficult to treat because the widely available options have low response rates. Careful and precise diagnosis and staging are essential to determine patient's risk and to select appropriate treatments. Fortunately, the recent progress in immunotherapy is very encouraging. In this context, it is important to characterize the intratumoral infiltration of immune cells in each patient, which is however not done routinely due to the lack of standardized methods. In this study, we used Fourier transform infrared (FTIR) imaging combined with multivariate statistical analyses to investigate non-metastatic and metastatic lymph nodes from melanoma patients. Our results show that the different cell types have different infrared spectral features allowing automated identification of these cell types. High recognition rates were obtained using a supervised partial least square discriminant analysis (PLS-DA) model. Melanoma cells were recognized with 87.1% sensitivity and 85.7% specificity, showing that FTIR spectroscopy has similar detection power as immunohistochemistry. Besides, FTIR imaging could also distinguish lymphocyte subpopulations (B and T cells). Finally, we investigated the changes in lymphocytes due to the presence of metastases. Interestingly, specific features of spectra of lymphocytes present in metastatic or tumor-free lymph nodes could be evidenced by PCA. A PLS-DA model was capable of predicting whether lymphocytes originated from invaded or non-invaded lymph nodes. These data demonstrate that FTIR imaging is capable to distinguish known and also novel biological features in human tissues, with potential practical relevance for histopathological diagnosis and biomarker assessment.

Acral, Superficial Spreading Melanoma Arising on Melanocytic Nevus in a Pregnant Woman: A Case Report with Review

We are reporting a case of superficial spreading melanoma (SSM) on left palm of a 37-year-old pregnant housewife. She had a small acquired melanocytic nevus on her left palm since childhood, which changed its consistency and color in the last 4 months. Dermoscopy of the lesion indicated malignant changes. The lesion was managed surgically using split-thickness skin graft. The histopathology report was suggestive of SSM with positive HMB-45 cells. SSM is very rare on the acral site, and it is very difficult to differentiate it from acral lentiginous melanoma. The rarity of the site (acral nonchronic sun damage) with evolution during pregnancy and importance of management approach are reasons for publishing this case.

Expression and prognostic value of putative cancer stem cell markers CD117 and CD15 in choroidal and ciliary body melanoma

AIMS

The aim of the present study was to immunohistochemically investigate the expression and prognostic significance of putative cancer stem cell markers CD117 (c-kit), CD34, CD20 and CD15 in a cohort of patients with primary choroidal and ciliary body melanoma.

METHODS

The immunohistochemical expression of these markers was evaluated using 3,3'-diaminobenzidine tetrahydrochloride (DAB) and 3-amino-9-ethylcarbazole (AEC) chromogens on paraffin-embedded tissue samples from 40 patients who underwent enucleation in the period from 1985 through 2000. Thirty-one patients had adequate tissue specimens for the analysis.

RESULTS

CD117 overexpression was observed in 12 of the 31 samples (39%) when AEC chromogen was used and in 14 of 26 (54%) samples when DAB was used. CD15 positivity was seen in three out of 30 (10%) samples with AEC and in six out of 26 (23%) samples with DAB. CD20 and CD34 exhibited no positivity in the tested samples. During the average follow-up time of 8.7 years (range 0.5-22 years), 17 patients (55%) died due to metastatic disease. The Kaplan-Meier plots showed a significantly shorter overall and disease-free survival in CD117-positive patients when the AEC chromogen was used. CD15 expression was not associated with patients' survival. In multivariate analysis, patients expressing the CD117 AEC had 4.13 times higher risk of lethal outcome in comparison with CD117 AEC negative patients.

CONCLUSIONS

Our retrospective cohort study has for the first time demonstrated a small proportion of CD15-positive uveal melanomas. CD117 AEC overexpression was associated with a worse outcome in patients with choroidal and ciliary body melanoma. Further studies should confirm the validity of these observations and their potential for targeted treatment modalities.

Value of dopachrome tautomerase detection in the assessment of melanocytic tumors

Dopachrome tautomerase (DCT) and tyrosinase (Tyr) are melanogenic enzymes and structurally related melanosomal proteins. The present study investigates DCT expression comparatively with Tyr, the most tested melanoma biomarker, aiming to evaluate DCT potential in the assessment of melanocytic tumors and gain insights into the molecular and pathological characterization of DCT-phenotype in tumor progression. DCT and Tyr are simultaneously analyzed in melanoma cell lines by semiquantitative RT-PCR, western blot, and N-glycan analysis, and in cell populations of melanocytic tumors by immunohistofluorescence using a novel anti-hDCT antibody against an extended sequence within DCT luminal domain. DCT, unlike Tyr, is fully processed along the secretory pathway in both pigmented and amelanotic melanoma cells. In 53 nevi and 116 primary malignant melanomas, 81% and 52%, respectively, are DCT+/Tyr+, showing that DCT is a stable antigen, retained by most tumors and partially expressed in Tyr-negative cell populations. The DCT/Tyr disjunction is a process correlated with melanocyte neoplastic transformation and malignant progression. A tumor architecture--DCT-phenotype-containing DCT+/Tyr- cell populations selected into the innermost dermis from double-positive cells is detected in 35% of DCT+/Tyr+ specimens. The DCT-phenotype is associated with enhanced neurotization in benign nevi and with ulceration in thin malignant melanomas. The intradermal DCT+/Tyr- clones in superficial melanomas acquire the expression and specific subcellular distribution of unfavorable prognostic markers. DCT assessment shows specific antigen patterns with potential significance in the outcome of melanocytic lesions, connecting DCT, a mediator of a melanoma stress-resistant pathway, and an antiapoptotic molecule to DCT- phenotypes that are possibly more stable and stress resistant.

Immunolabeling for p16, WT1, and Fli-1 in the assignment of growth phase for cutaneous melanomas

Distinction between radial growth phase (RGP) and vertical growth phase (VGP) in cutaneous melanomas is prognostically significant. Despite established morphological criteria, molecular markers to separate RGP and VGP have not been well established. The goal of this study was to investigate associations of p16, WT1, and Fli-1 with RGP-to-VGP progression, by immunohistochemistry. The p16 is a tumor suppressor, whereas WT1 and Fli-1 are transcriptional activators. The authors hypothesized that entry into VGP would be associated with decreased p16 and increased WT1 and Fli-1. Paraffin sections from 18 RGP and 15 VGP melanomas were immunostained with well-characterized antibodies to p16, WT1, and Fli-1. Melanoma growth phases were determined using precodified morphological attributes. In RGP melanomas, p16 was expressed in 15 of 18 (83%), WT1 in 17 of 17 (100%), and Fli-1 at least focally in 6 of 18 (33%). The deep dermal component of VGP melanomas stained positively for Fli-1 in 9 of 14 (64%), strongly for WT1 in 10 of 14 (71%), and strongly for p16 in only 2 of 15 (13%). Observed patterns of WT1 immunopositivity did not support the authors' hypothesis; it is not likely to be a good indicator of VGP. On the other hand, Fli-1 staining trended toward more positive deep tumor compartment staining and p16 to weaker staining in the deep compartment. At present, application of histological criteria remains the best method for assignment of growth phase in melanomas; however, p16 and possibly Fli-1 immunostains may serve as useful adjuncts in morphologically indeterminate cases.

How our practice of histopathology, especially tumour pathology has changed in the last two decades: reflections from a major referral center in Pakistan

Continued advances in the field of histo-pathology (and cyto-pathology) over the past two decades have resulted in dramatic changes in the manner in which these disciplines are now practiced. This is especially true in the setting of a large university hospital where the role of pathologists as clinicians (diagnosticians), undergraduate and postgraduate educators, and researchers has evolved considerably. The world around us has changed significantly during this period bringing about a considerable change in our lifestyles and the way we live. This is the world of the internet and the world-wide web, the world of Google and Wikipedia, of Youtube and Facebook where anyone can obtain any information one desires at the push of a button. The practice of histo (and cyto) pathology has also evolved in line with these changes. For those practicing this discipline in a poor, developing country these changes have been breathtaking. This is an attempt to document these changes as experienced by histo (and cyto) pathologists practicing in the biggest center for Histopathology in Pakistan, a developing country in South Asia with a large (180 million) and ever growing population. The Section of Histopathology, Department of Pathology and Microbiology at the Aga Khan University Hospital (AKUH) in Karachi, Pakistan's largest city has since its inception in the mid-1980s transformed the way histopathology is practiced in Pakistan by incorporating modern methods and rescuing histopathology in Pakistan from the primitive and outdated groove in which it was stuck for decades. It set histopathology in Pakistan firmly on the path of modernity and change which are essential for better patient management and care through accurate and complete diagnosis and more recently prognostic and predictive information as well.

Ultrasonographic staging of cutaneous malignant tumors: an ultrasonographic depth index

The objective of this paper is to assess the role of conventional and high-frequency ultrasound in the evaluation of the depth of cutaneous skin cancer. The study was performed on 46 subjects, divided into 3 categories, according to their skin pathology [basal cell carcinoma (BCC), 18 subjects; superficial spreading melanoma (SSM), 8 subjects; nodular melanoma (NM), 20 subjects]. Conventional and high-frequency ultrasonographic measurements were performed in order to assess the thickness of the tumors and the vascularization degree. We compared the mean values of the tumoral thickness obtained by using ultrasound (ultrasonographic depth index) with the histological depth index, obtained after performing histological sections stained with hematoxylin-eosin, and specific monoclonal antibodies in case of pigmented tumors. We established a correlation index between the histological and ultrasonographic values of the tumoral thickness. We found a strong correlation between the ultrasonographic index (measured by high-frequency sonography) and the histological index for nodular BCC (correlation of 98.4 %), NM subjects (correlation of 98.4 %), and SSM subjects (correlation of 99.4 %). An increase of the blood supply was noticed in nodular lesions only. Ultrasonography allows a very accurate assessment of skin cancer. The ultrasonographic depth index can be considered an objective, non-invasive marker for cutaneous tumors, comparable to the histological one, with a very good sensitivity (98-99 %).

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.

Multivalent Interactions: Synthesis and Evaluation of Melanotropin Multimers - Tools for Melanoma Targeting

In order to develop agents for early detection and selective treatment of melanomas, high affinity and high specificity molecular tools are required. Enhanced specificity may be obtained by simultaneously binding to multiple cell surface targets via the use of multimeric analogs of naturally occurring ligands. Trimers targeting overexpressed melanocortin receptors have been found to be potential candidates for this purpose. In the present letter, we describe the synthesis and study of multimers based on a dendrimer-like scaffold. The binding affinity and activity results revealed that dendrimers promote multivalent interactions via statistical and/or cooperative effects on binding. Moreover, viability studies showed no significant toxicity at micromolar concentrations, which will allow these molecular complexes to be used in vivo. Finally, imaging studies showed effective internalization for all the molecules confirming their potential as delivery agents.

Modifying effect of gender on the prognostic value of clinicopathological factors and Ki67 expression in melanoma: a population-based cohort study

Background

Malignant melanoma is the most deadly form of skin cancer. Female sex is known to have a protective effect on incidence, tumour characteristics, and mortality from melanoma. However, the potentially modifying effect of sex on the prognostic significance of clinicopathological and investigative factors is generally not taken into consideration in biomarker studies. In this study, we compared the sex-specific distribution and prognostic value of established tumour characteristics and Ki67 expression in 255 cases of incident primary melanoma in a prospective, population-based cohort study.

Methods

The study included 255 incident cases of melanoma, 132 females and 123 males, in the Malmö Diet and Cancer Study. Tumours from 226 (88.6%) cases had been assembled in tissue microarrays. Clinicopathological factors and immunohistochemical Ki67 expression were assessed and correlated with disease-free survival (DFS) and overall survival (OS) using Kaplan-Meier analysis, log rank test and univariable and multivariable Cox regression analyses, stratified for gender. Effect of gender on melanoma-specific survival (MSS) after first recurrence was also analysed.

Results

Women were significantly younger at diagnosis than men (p = 0.012). The most common tumour sites were the legs in women (37.5%) and the dorsal trunk in men (37.8%). Kaplan-Meier analysis revealed that tumour location had no prognostic impact in women, but in men, location to the frontal trunk was significantly associated with a reduced DFS compared with all other locations combined and location to the dorsal trunk was significantly associated with a prolonged OS. High Ki67 expression was significantly associated with a reduced DFS and OS in men but not in women, also when adjusted for other factors. In men, but not in women, ulceration was an independent prognostic factor for both DFS and OS. MSS after first local, regional or distant recurrence was significantly shorter for men than for women.

Conclusions

The results from this study demonstrate that the prognostic value of tumour location, Ki67 expression and ulceration in melanoma differs according to gender. These findings need to be validated in future studies, as they may help improve prognostication in patients with melanoma. Moreover, our findings demonstrate that sex-stratified analyses add valuable information to biomarker studies.

Methods of detection of circulating melanoma cells: a comparative overview

Disease dissemination is the major cause of melanoma-related death. A crucial step in the metastatic process is the intravascular invasion and circulation of melanoma cells in the bloodstream with subsequent development of distant micrometastases that is initially clinically undetectable and will eventually progress into clinically apparent metastasis. Therefore, the use of molecular methods to detect circulating melanoma cells may be of value in risk stratification and clinical management of such patients. Herein, we review the currently applied techniques for the detection, isolation, enrichment and further characterization of circulating melanoma cells from peripheral blood samples in melanoma patients. Furthermore, we provide a brief overview of the various molecular markers currently being evaluated as prognostic indicators of melanoma progression.

The immunohistochemistry of invasive and proliferative phenotype switching in melanoma: a case report

To date there is no effective therapy for metastatic melanoma and at the molecular level the disease progression is poorly understood. A recent study by our group led to the development of a novel phenotype switching model for melanoma progression, wherein cells transition back-and-forth between states of proliferation and invasion to drive disease progression. To explore the model's clinical relevance we interrogated phenotype-specific expression patterns in human melanoma patient material. A matched primary/metastasis pair from a human melanoma patient was obtained and immunohistochemically stained for proliferative and invasive phenotype markers. These were also stained for hypoxia and blood vessel markers. Proliferative phenotype markers Melan-A and Mitf showed consistent anti-correlation with invasive phenotype marker Wnt5A and hypoxia marker Glut-1. These also correlated with observed intra-tumoural vascularization patterns. Similar pattern distributions were present in both primary and metastasis samples. Strikingly, we observed that late phase metastatic melanoma cells adopt morphologies and behaviours identical to very early phase cells. The expression patterns observed closely matched expectations derived from previous in vitro and xenografting experiments. These results highlight the likelihood that disease progression involves melanoma cells retaining the capacity to regulate the expression of metastatic potential critical factors according to changing microenvironmental conditions.

Use of immunohistochemistry in the diagnosis of melanocytic lesions: applications and pitfalls

The accurate diagnosis of melanocytic lesions is essential for the adequate clinical management of the patients. Besides the histopathologic examination, immunohistochemical studies are often used as an adjunct in distinguishing melanocytic lesions from tumors with different origin or between benign and malignant melanocytic lesions. In the first part of this article, we analyze data on currently used immunohistochemical markers, with special emphasis on their applicability to clinical practice, and underline their potential pitfalls. The pathogenesis of malignant transformation of melanocytes is not completely understood. Recent studies report that various melanoma progression markers are preferentially expressed in benign or malignant melanocytic lesions or show different expression in subsequent stages of tumor development. Furthermore, in recent years, emerging genetic studies suggest that there are distinctive patterns of chromosomal aberrations in different subtypes of melanoma that can be altered by newly developed targeted therapies. In the second part of our article, we will discuss the most significant progression markers in melanoma that can be detected by immunohistochemistry and their potential usefulness for diagnosis, prognosis, staging or as therapeutic targets.

Immunohistochemical Identification of Canine Melanocytic Neoplasms With Antibodies to Melanocytic Antigen PNL2 and Tyrosinase

The immunoreactivity of PNL2 and antityrosinase in formalin-fixed, paraffin-embedded canine melanocytic neoplasms ( n = 101) was compared with that of Melan A. Of the 113 samples overall, 106 were positive for PNL2, 101 for Melan A, and 90 for tyrosinase. Six melanomas that were positive for PNL2 were negative for Melan A; 1 melanoma that was negative for PNL2 was positive for Melan A. Eighty tumors were positive for all 3 markers; 111 reacted with at least 1 the 3 antibodies. Decalcification with formic acid for up to 1 week did not affect immunoreactivity of any of the markers; however, decalcification with HCl for 1 day or 1 week notably decreased or completely abrogated immunoreactivity for Melan A and PNL2. There was only minor loss of immunoreactivity for tyrosinase in tissues decalcified with HCl for 1 week. Prolonged fixation (up to 2 months) did not affect PNL2 or tyrosinase immunoreactivity; however, Melan A immunoreactivity was reduced after 1 month of fixation. PNL2 was not expressed in 120 nonmelanocytic tumors (carcinomas, sarcomas, steroid-producing tumors, and leukocytic tumors). In summary, antibody PNL2 is slightly more sensitive than Melan A and more sensitive than tyrosinase in the identification of canine melanocytic neoplasms. Furthermore, PNL2 does not appear to cross-react with nonmelanocytic neoplasms. PNL2 is resistant to prolonged fixation but sensitive to strong decalcification. Results indicate that PNL2 is an excellent marker in the identification of canine melanomas and that the sensitivity is close to 100% when used in conjunction with Melan A and tyrosinase.

Quantitative measurements of formalin-induced fluorescence for differential diagnostics of melanomas and lesions of human skin

The usefulness of formaldehyde-induced fluorescence (FIF) for detection of melanoma cells has been suggested by several investigators during the last 40 years. FIF can be easily excited and observed in microscopic sections of formalin-fixed paraffin-embedded skin samples. However, such an approach has never been widely used in melanoma diagnostics for reasons including lack of clear diagnostic criteria, considerable inconsistencies in both the protocols used and qualitatively analysed results reported by different groups. This study aimed at determination of the spectral bands optimum for detecting melanoma cells. The study involved three sets of the excitation and emission bands: gammaex=366 nm, gammaem>425 nm; gammaex=450-480 nm, gammaem>515 nm; gammaex=450-480 nm, gammaem=510-550 nm. Microscopic digital imaging was used to quantitatively determine the fluorescence intensity of 53 primary melanomas and 32 benign lesions. Best classification of melanomas with algorithm based on fluorescence intensity threshold was obtained for gammaex=450-480 nm, gammaem=510-550 nm. Receiver operating characteristics (ROC) analysis of the algorithm yielded area under the curve=0.84 +/- 0.05 for melanocytic cells present in the stratum corneum. Our results clearly indicate that the FIF emitting molecules (most probably 5-S-cysteinyldopa) are present in melanomas at the concentration significantly higher than in benign lesions. In terms of the ROC analysis, the diagnostic performance of the test based on the FIF intensity is as good as of many other commonly used diagnostic tests.

The utility of PU.1 as an immunohistochemical marker for histiocytic and dendritic lesions of the skin

PU.1 is a transcription factor restricted to the hematopoietic system. It is expressed in myeloid lineage and B lymphocytes but is absent in mature T cells and nonhematopoietic cells. Among myeloid lineage-derived cells, PU.1 is overexpressed in monocytes, histiocytes, and dendritic cells. We evaluated PU.1 expression in 78 cases of primary skin neoplasms, including 9 reticulohistiocytomas, 9 Langerhans cell histiocytoses, 7 juvenile xanthogranulomas, 9 fibrous papules, 8 dermatofibromas, 12 dermatofibrosarcoma protuberans, 9 Spitz nevi, and 15 malignant melanomas. Strong nuclear staining for PU.1 was seen in all cases of histiocyte and dendritic cell origin, including 9/9 reticulohistiocytomas, 9/9 Langerhans cell histiocytoses, and 7/7 juvenile xanthogranulomas. No staining for PU.1 was seen in any studied cases of fibrous papules, dermatofibrosarcoma protuberans, dermatofibromas, Spitz nevi, or malignant melanomas. This study indicates that PU.1 is a valuable immunohistochemical marker for identifying cutaneous histiocyte- and dendritic cell-derived lesions. PU.1 staining is easily interpreted due to the sharp nuclear staining as compared with the irregular and often variable cytoplasmic staining seen with CD68.

Tissue biomarkers for prognosis in cutaneous melanoma: a systematic review and meta-analysis

In the clinical management of early-stage cutaneous melanoma, it is critical to determine which patients are cured by surgery alone and which should be treated with adjuvant therapy. To assist in this decision, many groups have made an effort to use molecular information. However, although there are hundreds of studies that have sought to assess the potential prognostic value of molecular markers in predicting the course of cutaneous melanoma, at this time, no molecular method to improve risk stratification is part of recommended clinical practice. To help understand this disconnect, we conducted a systematic review and meta-analysis of the published literature that reported immunohistochemistry-based protein biomarkers of melanoma outcome. Three parallel search strategies were applied to the PubMed database through January 15, 2008, to identify cohort studies that reported associations between immunohistochemical expression and survival outcomes in melanoma that conformed to the REMARK criteria. Of the 102 cohort studies, we identified only 37 manuscripts, collectively describing 87 assays on 62 distinct proteins, which met all inclusion criteria. Promising markers that emerged included melanoma cell adhesion molecule (MCAM)/MUC18 (all-cause mortality [ACM] hazard ratio [HR] = 16.34; 95% confidence interval [CI] = 3.80 to 70.28), matrix metalloproteinase-2 (melanoma-specific mortality [MSM] HR = 2.6; 95% CI = 1.32 to 5.07), Ki-67 (combined ACM HR = 2.66; 95% CI = 1.41 to 5.01), proliferating cell nuclear antigen (ACM HR = 2.27; 95% CI = 1.56 to 3.31), and p16/INK4A (ACM HR = 0.29; 95% CI = 0.10 to 0.83, MSM HR = 0.4; 95% CI = 0.24 to 0.67). We further noted incomplete adherence to the REMARK guidelines: 14 of 27 cohort studies that failed to adequately report their methods and nine studies that failed to either perform multivariable analyses or report their risk estimates were published since 2005.

Immunohistochemical characteristics of melanoma

Melanoma has a wide spectrum of histologic features which mimic epithelial, hematologic, mesenchymal, and neural tumors. Immunohistochemistry has been the primary tool to distinguish melanomas from these other tumors; it has also been studied for use as an adjunct to distinguish benign and malignant melanocytic tumors and to elucidate prognosis. Furthermore, there has been extensive effort to find a suitable marker to differentiate spindle cell and desmoplastic melanoma from other tumors. We have reviewed the literature investigating melanocytic differentiation markers, proliferation markers, immunomodulatory markers, signaling molecules, and nerve growth factors and receptors. Despite the proliferation of immunohistochemical markers, S-100 remains the most sensitive marker for melanocytic lesions, while markers such as HMB-45, MART-1/Melan-A, tyrosinase, and MITF demonstrate relatively good specificity but not as good sensitivity as S-100. No marker has proven useful in distinguishing spindle cell and desmoplastic melanomas from other tumors. Ki67 remains the most useful adjunct in distinguishing benign from malignant melanocytic tumors. None of the markers reviewed has been shown conclusively to have prognostic value for melanocytic neoplasms.

Cyclooxygenase-2 (COX-2): first immunohistochemical marker distinguishing early cutaneous melanomas from benign melanocytic skin tumours

We have reported recently that changes in expression level of COX-2 are correlated with development and progression of human melanoma. In this study, we investigated whether the COX-2 expression level might be a useful immunohistochemical marker for distinguishing cutaneous melanomas from benign melanocytic lesions. Up to now, immunohistochemical markers have not ensured satisfactory sensitivity and specificity of differential pathologic diagnosis of melanoma. The expression of COX-2 was determined immunohistochemically in formalin-fixed, paraffin-embedded specimens of 33 early Clark I/II melanomas and 58 naevi. Mean COX-2 expression in melanomas was significantly stronger than in naevi (P approximately 10(-13)). A simple diagnostic algorithm using threshold values of the COX-2 expression level allows for differentiation between early melanomas and naevi with high sensitivity (Se) and specificity (Sp) (for Se between 91 and 100%, Sp values change between 96.5 and 51.7%). Areas under the receiver operating characteristic curves were, respectively, 0.97+/-0.02 and 0.86+/-0.04 for the COX-2 expression in central and border regions of the lesions. For all the melanomas (not only the early ones),the respective areas under the ROC curve values were 0.98+/-0.01 and 0.97+/-0.02. In conclusion, COX-2 is the first immunohistochemical marker that allows the distinguishing of early melanomas from benign melanocytic lesions with both high sensitivity and specificity.

Cyclin-dependent kinase 2 expression in human melanomas and benign melanocytic skin lesions

Cyclin-dependent kinase 2 (CDK-2) is strongly involved in regulating the progression of the cell cycle through G1/S checkpoint and S phase. Numerous studies demonstrated increased levels of CDK-2 (and also of its regulatory cyclins E and/or A) in different types of human tumours. Correlations found between the expression of those cell cycle regulators and progression and/or invasiveness of some tumours indicated the importance of CDK-2 as a potential prognostic marker. At the same time, in vitro studies of melanoma cell lines revealed melanocyte-specific regulation of CDK-2. The present study was aimed at examining levels of CDK-2 in human melanomas and benign pigmented lesions to evaluate whether it might be considered a potential molecular marker of melanoma progression. Expression of CDK-2 was determined immunohistochemically in formalin-fixed paraffin-embedded specimens comprising 76 lesions including 41 primary cutaneous melanomas, 15 lymph node melanoma metastases (in eight cases correlated with primary tumours), three melanoma recurrences (two cases correlated with both primary and metastatic melanomas) and 17 nevi. Our results demonstrate that development and progression of melanoma are associated with changes in CDK-2 expression level. Statistical significance of the observed correlations indicates that CDK-2 may be a suitable prognostic marker for melanoma and perhaps also a target for chemotherapeutic drugs.

Pathologic Reporting and Special Diagnostic Techniques for Melanoma

Pathologists play a central role in the management of cutaneous melanoma in determining that a tumor is a melanoma, whether or not it is primary or metastatic, and whether or not the margins of excision are tumor free and in evaluating prognostic indicators from examination of the primary tumor and, where appropriate, lymph nodes, including the sentinel nodes.

Biologic and prognostic significance of dermal Ki67 expression, mitoses, and tumorigenicity in thin invasive cutaneous melanoma

PURPOSE

Tumor cell proliferation is a central feature of melanoma progression. In this study, we characterized three biomarkers of proliferation (Ki67 expression, dermal mitotic rate [MR], and tumorigenicity) in thin (< or = 1.00 mm) primary cutaneous melanomas and examined their association with prognosis.

PATIENTS AND METHODS

We used immunohistochemistry to determine Ki67 expression using the monoclonal antibody MIB-1 in lesions from a prospective cohort that included 396 patients with thin invasive primary melanomas seen between 1972 and 1991. A multivariate Cox proportional hazards model was used to define independent prognostic factors, and recursive partitioning was used to develop a prognostic tree identifying risk groups.

RESULTS

Dermal Ki67 expression was lower than epidermal Ki67 expression in radial growth phase (RGP) melanomas (n = 171), and dermal Ki67 expression and MR were higher in tumorigenic vertical growth phase (VGP) melanomas (n = 193) compared with RGP and nontumorigenic VGP melanomas (n = 42). Dermal Ki67 expression, MR greater than 0, growth phase, thickness, ulceration, tumor-infiltrating lymphocytes, and sex were associated with metastasis at 10 years, however, only dermal Ki67 expression, MR greater than 0, and sex were independent prognostic factors. Two high-risk groups were identified: men and women with dermal MR greater than 0 and dermal Ki67 expression > or = 20% in tumor cells and men with MR greater than 0 and Ki67 expression less than 20%, with 10-year metastasis rates of 39% and 20%, respectively.

CONCLUSION

Proliferation slows as melanoma cells enter the dermis and then increases with the onset of tumorigenic VGP. Ki67 expression and dermal MR provide independent prognostic information that can potentially be used in risk-based management of patients.