Proliferation assessment in breast carcinomas using digital image analysis based on virtual Ki67/cytokeratin double staining.

Manual estimation of Ki67 Proliferation Index (PI) in breast carcinoma classification is labor intensive and prone to intra- and interobserver variation. Standard Digital Image Analysis (DIA) has limitations due to issues with tumor cell identification. Recently, a computer algorithm, DIA based on Virtual Double Staining (VDS), segmenting Ki67-positive and -negative tumor cells using digitally fused parallel cytokeratin (CK) and Ki67-stained slides has been introduced. In this study, we compare VDS with manual stereological counting of Ki67-positive and -negative cells and examine the impact of the physical distance of the parallel slides on the alignment of slides. TMAs, containing 140 cores of consecutively obtained breast carcinomas, were stained for CK and Ki67 using optimized staining protocols. By means of stereological principles, Ki67-positive and -negative cell profiles were counted in sampled areas and used for the estimation of PIs of the whole tissue core. The VDS principle was applied to both the same sampled areas and the whole tissue core. Additionally, five neighboring slides were stained for CK in order to examine the alignment algorithm. Correlation between manual counting and VDS in both sampled areas and whole core was almost perfect (correlation coefficients above 0.97). Bland-Altman plots did not reveal any skewness in any data ranges. There was a good agreement in alignment (>85 %) in neighboring slides, whereas agreement decreased in non-neighboring slides. VDS gave similar results compared with manual counting using stereological principles. Introduction of this method in clinical and research practice may improve accuracy and reproducibility of Ki67 PI.

Tumour-associated mast cells in classical Hodgkin's lymphoma: correlation with histological subtype, other tumour-infiltrating inflammatory cell subsets and outcome.

The tumour microenvironment in classical Hodgkin's lymphoma (cHL) is characterised by a minor population of neoplastic Hodgkin and Reed-Sternberg cells within a heterogeneous background of non-neoplastic bystanders cells, including mast cells. The number of infiltrating mast cells in cHL has been reported to correlate with poor prognosis. We used immunohistochemistry to assess the degree of tumour-infiltrating mast cells in cHL tissue microarrays and correlated this with clinico-pathological features and prognosis in a cohort of homogeneously treated patients with Hodgkin's disease. A high degree of tumour mast cells was associated with nodular sclerosis (NS) subtype histology (P = 0.0002). Moreover, the number of mast cells was inversely correlated with the numbers of CD68+ and CD163+ macrophages (P = 0.0001 and P = 0.003, respectively) and with the number of granzyme+ cytotoxic cells (P = 0.004). The degree of mast cell infiltration was not a prognostic factor in cHL of nodular sclerosis subtype. In contrast, in mixed cellularity cHL a high number of intratumoral mast cells correlated with significantly poorer outcome both in terms of overall (P = 0.03) and event-free survival (P = 0.01). Further studies are warranted into the biological mechanisms underlying this adverse outcome and their possible therapeutic implications.

Proliferation indices of phosphohistone H3 and Ki67: strong prognostic markers in a consecutive cohort with stage I/II melanoma.

Cellular proliferation is correlated with the progression of melanoma. Accordingly, the proliferation index of H&E-stained thin melanomas was recently included in the staging system of the American Joint Committee on Cancer. Yet, the immunohistochemical markers of proliferation phosphohistone H3 and Ki67 may improve such indices. To accurately quantify these markers, they should be combined with a melanocytic marker, for example, MART1 in an immunohistochemical double stain; also enabling automated quantification by image analysis. The aim of the study was to compare the prognostic impact of phosphohistone H3/MART1, Ki67/MART1, and H&E stains in primary cutaneous melanoma, and to determine the difference between indices established in hot spots and the global tumor areas. The study included 153 consecutive stage I/II melanoma-patients. The follow-up time was 8-14 years for event-free melanoma. Recurrent disease occurred in 43 patients; 37 died of melanoma. Both events occurred in only three thin melanomas. Their paraffin-embedded tissue was stained for phosphohistone H3/MART1, Ki67/MART1, and with H&E. And proliferation indices were established in 1-mm(2) hot spots and in the global tumor areas. In multivariate Cox analyses, only hot spot indices of phosphohistone H3/MART1 and Ki67/MART1 were independent prognostic markers. Phosphohistone H3/MART1 tended to be better than Ki67/MART1 with adjusted hazard ratios of 3.66 (95% CI, 1.40-9.55; P=0.008) for progression-free survival and 3.42 (95% CI, 1.29-9.04; P=0.013) for melanoma-specific death. In all stains, prognostic performance was substantially improved by using hot spots instead of the global tumor areas. In conclusion, phosphohistone H3/MART1 and Ki67/MART1 were superior to H&E stains, and hot spots superior to the global tumor areas. Given the potential for automated analysis, these double stains seem to be robust alternatives to conventional mitotic detection by H&E in stage I/II melanomas in general. This was particularly true for thick melanomas whereas no specific analyses for thin melanomas only could be performed.

A Rare Case of Prurigo Pigmentosa in a Danish Sibling Couple.

Prurigo pigmentosa (PP) is probably underdiagnosed due to lack of awareness. Previously, it was assumed that PP primarily affected Japanese females; however, more cases are reported worldwide, and the pathogenesis is still not completely understood. In this case report, we present two healthy Danish siblings, who developed PP approximately 2 weeks after starting a ketogenic diet, suggesting that both increased levels of ketone bodies in the blood together with a genetic predisposition might play a role in the development of PP.

Automated digital volume measurement of melanoma metastases in sentinel nodes predicts disease recurrence and survival.

AIMS: Total metastatic volume (TMV) is an important prognostic factor in melanoma sentinel lymph nodes (SLNs) that avoids both the interobserver variation and unidirectional upstaging seen when using semi-quantitative size estimates. However, it is somewhat laborious for routine application. Our aim was to investigate whether digital image analysis can estimate TMV accurately in melanoma SLNs. METHODS AND RESULTS: TMV was measured in 147 SLNs from 95 patients both manually and by automated digital image analysis. The results were compared by Bland-Altman plots (numerical data) and kappa statistics (categorical data). In addition, disease-free and melanoma-specific survivals were calculated. Mean metastatic volume per patient was 10.6 mm(3) (median 0.05 mm(3); range 0.0001-621.3 mm(3)) and 9.62 mm(3) (median 0.05 mm(3); range 0.00001-564.3 mm(3)) with manual and digital measurement, respectively. The Bland-Altman plot showed an even distribution of the differences, and the kappa statistic was 0.84. In multivariate analysis, both manual and digital metastasis volume measurements were independent progression markers when corrected for primary tumour thickness [manual: hazard ratio (HR): 1.21, 95% confidence interval (CI): 1.07-1.36, P = 0.002; digital: HR: 1.21, 95% CI: 1.06-1.37, P = 0.004]. CONCLUSIONS: Stereology-based, automated digital metastasis volume measurement in melanoma SLNs predicts disease recurrence and survival.

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.

Ki-67 Proliferation Index in Breast Cancer as a Function of Assessment Method: A NordiQC Experience.

Immunohistochemical staining for Ki-67 is used to calculate a Ki-67 proliferation index (PI) that carries prognostic and predictive information in various cancers including breast carcinomas. Studies have documented challenges for observers to reproducibly estimate the Ki-67 PI. At present, no international consensus exists concerning scoring method (eg, hotspots vs. overall average, digital vs. manual counting) or even the definition of a Ki-67-positive cell. To clarify the approach to Ki-67 scoring and evaluation of the interobserver agreement among participants in the Nordic Immunohistochemical Quality Control (NordiQC) Breast Cancer Module, a study was set up on the basis of an online web module containing 15 digitized tissue microarray cores of breast carcinomas stained for Ki-67 in the NordiQC reference laboratory. All participants were invited to attend the study. In addition to Ki-67 scoring, they were asked to disclose their preferred method for Ki-67 estimation and their job title. For comparison, slides were analyzed using a Digital Image Analysis algorithm based on Virtual Double Staining. In total, 199 participants enrolled for the study. Overall, there was a good correlation in Ki-67 PIs among the participants, although results for some cores varied significantly. However, when applying a cutoff of 20%, a relatively low κ value of 0.52 was observed. Participants scoring in hotspots reported higher Ki-67 PIs than participants estimating an overall average, and, not surprisingly, participants who considered weak Ki-67 nuclear staining positive obtained higher Ki-67 PIs than those who did not. Ki-67 PI was not correlated to job title. The Virtual Double Staining algorithm obtained Ki-67 values close to the mean value of the human observers. Our study underlines the need for international standardization and guidelines in estimation of Ki-67 PI. Digital Image Analysis may be a useful tool in this process.

Eosinophilic pustular folliculitis of infancy: A rare diagnosis in children.

Remember EPFI as a differential diagnosis in children with a rash on the scalp and no effect of antibiotic treatment.

Metastatic melanoma volume in sentinel nodes: objective stereology-based measurement predicts disease recurrence and survival.

AIMS: Sentinel lymph node (SLN) status is the most important prognostic factor in intermediate thickness melanoma. The amount of metastatic disease in positive SLNs varies greatly between patients, and this tumour burden appears to influence the prognosis of node-positive patients. The aim was to use objective stereological techniques to correlate accurately total SLN tumour burden with recurrence and patient survival. METHODS AND RESULTS: SLNs from 327 patients were examined by complete step sectioning and immunohistochemistry. The total metastasis volume (TMV) of 156 positive SLNs from 99 patients (30.3%) was measured using stereological methods based on the 2D-nucleator and Cavalieri's principle. The maximum metastasis diameter was also measured. These two measurements were correlated with disease recurrence and patient survival. The mean TMV for SLN+ patients was 10.5 mm(3) (median 0.05 mm(3); range 0.0001-623.7 mm(3)). Median follow-up was 26.3 months. On multivariate analysis, TMV was an independent predictor of recurrence when corrected for primary tumour thickness (P = 0.001) and was a stronger prognosticator compared with the maximum metastasis diameter (P < 0.0001 versus P = 0.01). CONCLUSIONS: Combining total step sectioning of SLNs with stereological assessment of metastases, we found metastasis volume to be a highly significant predictor of disease recurrence and survival.

Impact of Primary Antibody Clone, Format, and Stainer Platform on Ki67 Proliferation Indices in Breast Carcinomas.

Ki67 is a nuclear protein expressed during the active phases of the cell cycle, which makes it a biomarker of cell proliferation. In clinical pathology settings, immunohistochemical (IHC) detection of Ki67 is used to calculate Ki67 proliferation indices (PIs), which have prognostic information and are used to subdivide breast carcinomas and neuroendocrine neoplasias. Calculation of Ki67 PIs is notoriously hard and prone to intraobserver and interobserver variance. In addition, IHC protocol settings [such as primary antibody (Ab) clone, clone format, and stainer platform] can affect the result of the IHC assays and in turn the Ki67 PI. Digital image analysis has been suggested as a useful tool to standardize Ki67 counting. Recently, virtual double staining, a computer algorithm segmenting Ki67 and Ki67 tumor cells using digitally fused parallel cytokeratin and Ki67-stained slides, has been introduced. In this study, we compare Ki67 PIs obtained by virtual double staining in 41 breast carcinomas stained using the most commonly used commercially available primary Ab clones and formats on the main stainer platforms. IHC protocols for the concentrated (conc) Ab and platform combinations were optimized for the highest analytical sensitivity and optimal signal-to-noise ratio, whereas ready-to-use (RTU) formats were used, as recommended by the vendor. Significant differences in the mean Ki67 PIs (relativized to the mean core Ki67) were observed not only between the different Ab clones but also the different formats and stainer platforms; Ki67 PIs with SP6 conc stained on the Ventana BenchMark ULTRA platform were on average 11.9 percentage points (pp) higher than the mean core average, whereas with Ab 30.9 RTU on the Ventana platform, they were 10.4 pp higher. Mib1 RTU (Dako Autostainer Link 48) and MM1 RTU (Leica Bond) provided 8.6 and 12.5 pp lower Ki67 PIs, respectively. Mib1 conc and SP6 conc on the Dako Autostainer and Leica Bond provided similar results-close to the overall average. Significant variations in the proportion of tumors with Ki67 high-level expression (Ki67 PI ≥20%) were observed among Ab, format, and stainer platform combinations. The results underline the challenges in the comparison of Ki67 PIs across Abs, formats, and platforms. Researchers and clinicians need to account for these differences when reporting Ki67 PIs. To advance the usefulness of Ki67 PIs in the research and clinical setting, standardization of Ki67 IHC assays is needed.

Severe Infantile Bullous Pemphigoid Treated with Dapsone after Bridging with Systemic Glucocorticoid.

We present a case of severe and treatment-refractory bullous pemphigoid in a 3-month-old child. After topical and systemic corticoid treatment proved inefficient, dapsone 0.75 mg/kg was added initially without success. Disease control was reached with dapsone 1.5 mg/kg in addition to both topical and systemic glucocorticoid treatment, leaving the child with several side effects of the glucocorticoid treatment.

Extensive pathological analysis of selected melanoma sentinel lymph nodes: high metastasis detection rates at reduced workload.

BACKGROUND: Extensive pathological workup of sentinel lymph nodes (SLNs) in melanoma detects more patients with metastasis-positive SLNs than do routine protocols, but at the cost of high laboratory workloads. We aimed to design a protocol that reduced this workload without compromising metastasis detection. METHODS: We analyzed 920 SLNs from 321 consecutive patients with melanoma by complete step sectioning and immunohistochemistry. We designed different models to theoretically reduce the number of histological sections examined and compared the results from these simulations with results obtained with our extended protocol, with the restricted national Danish protocol, and with the protocol recommended by the European Organization for Research and Treatment of Cancer (EORTC). RESULTS: The extended protocol increased the metastasis detection rate by 22% (95% confidence interval, 11-34; 30.8% vs. 25.2%, P < .0001) compared with the national Danish protocol, and it had a similar rate to that reported by the EORTC (30.8% vs. 29.4%, P = .6229). The workload associated with complete step sectioning could be reduced by 40% by focusing step sectioning on the SLNs with the highest gamma counts, while examining SLNs with lower gamma counts with one to three central sections. The false-negative rate for detecting metastases with this reduced protocol was 6% compared with complete step sectioning. CONCLUSIONS: Combining complete step sectioning of SLNs with immunohistochemistry ensures high metastasis detection rates. Workloads can be markedly reduced with only a slight increase in the false-negative rate by focusing analysis on the SLNs most likely to contain metastases, i.e., those with the highest gamma counts.

Quantitative real-time RT-PCR in sentinel lymph nodes from melanoma patients. Detection of melanocytic mRNA predicts disease-free survival.

Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) for specific melanoma markers is more sensitive than histology for detecting cells of melanocytic origin in sentinel lymph nodes (SLNs) in cutaneous melanoma. The clinical significance of a positive qRT-PCR analysis is unclear. We performed qRT-PCR for the presence of MART-1 and tyrosinase in SLNs from 93 melanoma patients, and then followed these patients clinically (median follow-up time 43.5 months). We found a significant correlation between disease progression and presence of MART-1 mRNA in SLNs (p=0.02), but no correlation with the amount of MART-1 mRNA as measured by qRT-PCR. No correlation between histology and recurrence was detected, recurrence rates being low in both histology-negative (12%) and -positive (15%) patients. We found a significant difference in disease recurrence between patients positive by both histology and RT-PCR and patients negative by both methods (15% vs 0%, p=0.02). However, a significant difference in disease recurrence was also found when comparing patients negative by both methods with patients positive by RT-PCR but negative by histology (0% vs 19%, p=0.009). This suggests that the presence of submicroscopic metastases may influence prognosis, indicating that RT-PCR detection of melanocytic cells in SLNs may be an important diagnostic marker.

Immunohistochemical CD271 expression correlates with melanoma progress in a case-control study.

Putative cancer stem cell (CSC) markers have arisen from melanoma mouse and in vitro models, but their expression in paraffin embedded patient samples relative to clinical outcome remains largely unexplored. Rather than cells of the tumour bulk, conceivably, CSC drive tumour progression. Accordingly, complete eradication may prevent melanoma relapse. Because elevated tumour-cell proliferation is an established indicator of aggressive disease, this study aimed to investigate the correlation between melanoma recurrence and proliferation of putative CSC that express CD271, CD166, or CD20. Additionally, the expression of these markers was studied in naevi, melanomas, and their recurrence. In melanoma patients, 30 with relapse (cases) and 30 without (controls) were matched for tumour thickness, ulceration, Clark level, subtype, site, gender, and age. One paraffin-embedded section of the patients' primary melanoma (n = 60), relapse (n = 21), and naevus (n = 17) were immunohistochemically double-stained for Ki-67/MART1 and single-stained for CD271, CD166, and CD20. Their whole slide images were aligned as virtual quadruple stains. Image analysis established proliferation indices of each putative stem cell marker and the tumour bulk in addition to the markers' percentage level in tumour areas and the epidermis. In cases vs controls, median dermal proliferation indices (no./mm2) were 211 vs 103 (p = 0.04) for CD271, 512 vs 227 (p = 0.3) for CD166, 184 vs 97 (p = 0.3) for CD20, and 95 vs 103 (p = 0.6) for the tumour bulk. Of additional interest, epidermal CD271+ keratinocytes totalled 8.8% in naevi and 0.98% in melanomas (p = 0.0007). Even though differences between naevi and melanomas also were observed for CD166 in both the epidermis (p = 0.002) and dermis (p = 0.006), they were visually less apparent. CD20+MART1+ cells were absent in half of the melanomas, and all naevi and relapses. In conclusion, high levels of CD271+Ki-67+MART1+ cells were linked to melanoma relapse as opposed to common Ki-67 indices in this particular case-control study. With further investigation, such cells could be potential targets of therapy. Especially, loss of epidermal CD271+ keratinocytes seemed necessary for melanoma development; hence, identification may serve as a diagnostic tool with additional research.

Telomerase reverse transcriptase promoter mutations and solar elastosis in cutaneous melanoma.

The aims of this study were to assess the prognostic potential of solar elastosis grading and telomerase reverse transcriptase (TERT) promoter mutations (TERTp) in melanoma and to evaluate whether an association between solar elastosis and TERTp exists. Solar elastosis in the dermis was evaluated in hematoxylin and eosin-stained whole slides from 486 malignant melanomas. Pyrosequencing was used to detect TERTp in 189 samples. There was no association between solar elastosis and TERTp (P=0.3). Severe elastosis was associated with older age (P<0.0001), ulceration (P=0.03), and location in the head/neck region (P<0.0001). The absence of elastosis was associated with younger age (P<0.0001), benign nevus remnants (P=0.001), and a positive BRAF V600E expression (P<0.0001). Severe elastosis predicted a worse relapse-free survival (hazard ratio: 2.18; 95% confidence interval: 1.30-3.64; P=0.003). However, it was not independent of age. TERTp was not associated with any adverse prognostic or clinicopathological outcome, nor any mitogen-activated protein kinase-related protein expressions. However, at a cutoff corresponding to the sensitivity of Sanger sequencing, TERTp predicted melanoma-specific death independently of age, and was associated with Breslow thickness, ulceration, tumor stage at diagnosis, BRAF V600E oncoprotein, and absence of p16 expression. In conclusion, TERTp were not related to severe elastosis and may thus be triggered by both chronic and acute intermittent sun exposure, the latter not visible on ordinary hematoxylin and eosin-stained slides. Neither TERTp nor severe elastosis predicted an adverse outcome in melanoma. An absence of elastosis was seen in younger melanoma patients and may be used to select those melanomas originating in a nevus, which often harbors a BRAF mutation.

Ibrutinib-Associated Skin Toxicity: A Case of Maculopapular Rash in a 79-Year Old Caucasian Male Patient with Relapsed Waldenstrom's Macroglobulinemia and Review of the Literature.

Waldenstrom's macroglobulinamia (WM) is a rare malignant lymphoproliferative disorder, characterized by monoclonal IgM paraproteinemia and neoplastic proliferation of malignant lymphoplasmacytoid cells in the bone marrow. Traditionally, WM has been treated with modalities similar to those used in the management of other indolent lymphomas. Just recently, based on impressive clinical trial results in heavily pretreated WM patients, a new Bruton Tyrosine Kinase-inhibitor, Ibrutinib, has been approved for the treatment of this disorder. As the use of Ibrutinib in WM outside clinical trials is still limited, only few clinical reports illustrating treatment side effects are currently available. Here we review the current literature specific on Ibrutinib-associated rash in hematologic patients, and report on an elderly patient with WM, who developed a red maculopapular non-pruritic rash 12 weeks after starting Ibrutinib therapy. Without modifications of the ongoing Ibrutinib schedule, the rash regressed within two weeks of treatment with topical steroid-containing dermatological compounds.

Quantification of microRNA-21 and microRNA-125b in melanoma tissue.

Although microRNAs (miRNAs) have emerged as potent mediators of melanoma development and progression, a precise understanding of their oncogenic role remains unclear. In this study, we analysed formalin-fixed and paraffin-embedded tissues from two separate melanoma cohorts and from a series of benign melanocytic nevi. Using three different quantification methods [array analysis, quantitative PCR (qPCR) and in-situ hybridization (ISH) quantified by digital image analysis], we found considerable miRNA dysregulation in tumours. Using array analysis, samples mainly clustered according to their biological group (benign vs. malignant) and 77 miRNAs differed significantly between nevi and melanoma samples. Increase of miR-21 and miR-142, and decrease of miR-125b, miR-211, miR-101 and miR-513c in the melanomas were verified in both cohorts using qPCR, whereas the decrease of miR-205 observed with array analysis could not be confirmed using qPCR. ISH with digital quantification showed expression of miR-21 and miR-125b in the melanocytic lesions. miR-21 ISH was increased in melanomas, whereas quantification of miR-125b showed uniform ISH expression across nevi and melanomas. Our results support the important involvement of different miRNAs in melanoma biology and may serve as solid basics for further miRNA investigations in melanoma formalin-fixed and paraffin-embedded tissue. In particular, there is increased expression of miR-21 in melanomas compared with benign nevi.

Automated quantification of proliferation with automated hot-spot selection in phosphohistone H3/MART1 dual-stained stage I/II melanoma.

BACKGROUND: Staging of melanoma includes quantification of a proliferation index, i.e., presumed melanocytic mitoses of H&E stains are counted manually in hot spots. Yet, its reproducibility and prognostic impact increases by immunohistochemical dual staining for phosphohistone H3 (PHH3) and MART1, which also may enable fully automated quantification by image analysis. To ensure manageable workloads and repeatable measurements in modern pathology, the study aimed to present an automated quantification of proliferation with automated hot-spot selection in PHH3/MART1-stained melanomas. METHODS: Formalin-fixed, paraffin-embedded tissue from 153 consecutive stage I/II melanoma patients was immunohistochemically dual-stained for PHH3 and MART1. Whole slide images were captured, and the number of PHH3/MART1-positive cells was manually and automatically counted in the global tumor area and in a manually and automatically selected hot spot, i.e., a fixed 1-mm(2) square. Bland-Altman plots and hypothesis tests compared manual and automated procedures, and the Cox proportional hazards model established their prognostic impact. RESULTS: The mean difference between manual and automated global counts was 2.9 cells/mm(2) (P = 0.0071) and 0.23 cells per hot spot (P = 0.96) for automated counts in manually and automatically selected hot spots. In 77 % of cases, manual and automated hot spots overlapped. Fully manual hot-spot counts yielded the highest prognostic performance with an adjusted hazard ratio of 5.5 (95 % CI, 1.3-24, P = 0.024) as opposed to 1.3 (95 % CI, 0.61-2.9, P = 0.47) for automated counts with automated hot spots. CONCLUSIONS: The automated index and automated hot-spot selection were highly correlated to their manual counterpart, but altogether their prognostic impact was noticeably reduced. Because correct recognition of only one PHH3/MART1-positive cell seems important, extremely high sensitivity and specificity of the algorithm is required for prognostic purposes. Thus, automated analysis may still aid and improve the pathologists' detection of mitoses in melanoma and possibly other malignancies.

KIT is a frequent target for epigenetic silencing in cutaneous melanoma.

The receptor tyrosine kinase KIT and its ligand, stem cell factor (SCF), are essential for the proliferation and survival of normal melanocytes. In melanomas arising on mucosal, acral, and chronically sun-damaged skin, activating KIT mutations have been identified as oncogenic drivers and potent therapeutic targets. Through an initial whole-genome screen for aberrant promoter methylation in melanoma, we identified the KIT promoter as a target for hypermethylation in 43/110 melanoma cell lines, and in 3/12 primary and 11/29 metastatic cutaneous melanomas. Methylation density at the KIT promoter correlated inversely with promoter activity in vitro and in vivo, and the expression of KIT was restored after treatment with the demethylating agent 5-aza-2'-deoxycytidine. Hypermethylation of KIT showed no direct or inverse correlations with well-documented melanoma drivers. Growth of melanoma cells in the presence of SCF led to reduced KIT expression and increased methylation density at the KIT promoter, suggesting that SCF may exert a selection pressure for the loss of KIT. The frequent loss of KIT in cutaneous melanoma by promoter hypermethylation suggests that distinct KIT signaling pathways have opposing roles in the pathogenesis of melanoma subtypes.