Jürgen Kreusch

How to diagnose nonpigmented skin tumors: A review of vascular structures seen with dermoscopy: Part II. Nonmelanocytic skin tumors

Dermoscopy is a noninvasive tool that can be helpful in the diagnosis of nonpigmented skin tumors. This is because dermoscopy permits the visualization of key vascular structures that are usually not visible to the naked eye. Much work has concentrated on the identification of specific morphologic types of vessels that allow a classification into melanocytic versus nonmelanocytic and benign versus malignant nonpigmented skin tumors. Among a broad spectrum of different types of vascular patterns, six main morphologies can be identified. These are comma-like, dotted, linear-irregular, hairpin, glomerular, and arborizing vessels. With some exceptions, comma, dotted, and linear irregular vessels are associated with melanocytic tumors, while the latter three vascular types are generally indicative of keratinocytic tumors. Aside from vascular morphology, the architectural arrangement of vessels within the tumor and the presence of additional dermoscopic clues are equally important for the diagnosis. This article provides a general overview of the dermoscopic evaluation of nonpigmented skin tumors and is divided into two parts. Part I discusses the dermoscopic vascular patterns of benign and malignant melanocytic skin tumors. Part II discusses the dermoscopic vascular patterns of benign and malignant nonmelanocytic nonpigmented skin tumors. In each part, additional special management guidelines for melanocytic and nonmelanocytic nonpigmented skin tumors, respectively, will be discussed.

How to diagnose nonpigmented skin tumors: A review of vascular structures seen with dermoscopy

Nonmelanoma skin cancer refers to a broad class of tumors, including actinic keratosis, basal cell carcinoma, and squamous cell carcinoma, and as a group these are the most frequent cancers occurring in light skinned humans. In contrast to the rarity of amelanotic melanoma, nonmelanoma skin cancer commonly lacks pigmentation. Although these tumors rarely cause death related to metastases, they commonly destroy underlying tissues and should be removed at the earliest possible stage. Dermoscopy improves the clinical diagnosis of nonpigmented skin tumors by allowing the visualization of specific vascular structures that are usually not visible to the naked eye. Dermoscopic vascular patterns of several nonmelanocytic nonpigmented skin tumors, such as sebaceous hyperplasia, seborrheic keratosis, clear cell acanthoma, Bowen disease, or nodular cystic basal cell carcinoma are highly specific, allowing a ready diagnosis in most cases. Others, such as actinic keratosis, pyogenic granuloma, or uncommon adnexal tumors, may be difficult to differentiate even with the aid of dermoscopy. For this reason, general guidelines have been established to assist in making the most appropriate management decision. In the second part of this review of dermoscopic vascular structures of nonpigmented skin tumors, the dermoscopic patterns associated with benign and malignant nonmelanocytic skin tumors and recommendations for the management of these tumors will be discussed.

Feature selection for optimized skin tumor recognition using genetic algorithms

In this paper, a new approach to computer supported diagnosis of skin tumors in dermatology is presented. High resolution skin surface profiles are analyzed to recognize malignant melanomas and nevocytic nevi (moles), automatically. In the first step, several types of features are extracted by 2D image analysis methods characterizing the structure of skin surface profiles: texture features based on cooccurrence matrices, Fourier features and fractal features. Then, feature selection algorithms are applied to determine suitable feature subsets for the recognition process. Feature selection is described as an optimization problem and several approaches including heuristic strategies, greedy and genetic algorithms are compared. As quality measure for feature subsets, the classification rate of the nearest neighbor classifier computed with the leaving-one-out method is used. Genetic algorithms show the best results. Finally, neural networks with error back-propagation as learning paradigm are trained using the selected feature sets. Different network topologies, learning parameters and pruning algorithms are investigated to optimize the classification performance of the neural classifiers. With the optimized recognition system a classification performance of 97.7% is achieved.

Auflichtmikroskopische Charakterisierung von Gefäßmustern in Hauttumoren

ZusammenfassungDie auflichtmikroskopische Suche nach vaskulären Strukturen in Hauttumoren ergab, daß Blutgefäße viel häufiger sichtbar waren als mit dem bloßen Auge. Es wurden charakteristische, z.T. sehr tumorspezifische Gefäßmuster festgestellt und ihre Häufigkeitsverteilung bestimmt. Das Vaskularisierungsmuster erwies sich als wichtiges Element zur auflichtmikroskopischen Charakterisierung von Hauttumoren, insbesondere zur Diagnose amelanotischer Melanome. Wir stellen ein diagnostisches Flußdiagramm für die systematische auflichtmikroskopische Beurteilung von Hauttumoren vor, welches sich u.a. als Grundlage für verbesserte bildanalytische Untersuchungen anbietet.SummaryThe search for vascular structures in skin tumors by incident light microscopy has revealed a surprisingly high proportion of vascularized tumours. Characteristic vascular patterns, in some cases highly tumour-specific, have been defined. The vascular structure is a valuable feature for characterization and differentiation of skin tumours, especially for amelanotic malignant melanoma. We propose a flowchart procedure for analysis and diagnosis of skin tumours using incident light microscopy, which appears to be valuable for advanced image analytic techniques.

Dermoscopy Key Points: Recommendations from the International Dermoscopy Society

J. Bowling G. Argenziano A. Azenha J. Bandic R. Bergman A. Blum H. Cabo A. Di Stephani J. Grichnik A. Halpern R. Hofman-Wellenhof R. Johr H. Kittler A. Kopf J. Kreusch D. Langford J. Malvehy A. Marghoob S. Menzies F. Ozdemir K. Peris D. Piccolo M.A. Pizzichetta D. Polsky S. Puig H. Rabinovitz P. Rubegni T. Saida M. Scalvenzi S. Seidenari H.P. Soyer M. Tanaka I. Zalaudek R.P. Braun

Automatic Classsification of Skin Tumours with High Resolution Surface Profiles

This paper describes a new approach to automatic classification of melanocytic tumours based on features extracted from profilometric data. The clinical accuracy of dermatologists in identifying these tumours is only approximately 75%. Automatic classification is based on high resolution skin surface profiles of 4×4 mm2 size with 125 sample points per mm, generated with a laser profilometer. Three categories of profile features are extracted: Textural features, Fourier features and fractal features. Feature selection is performed to determine an optimal feature subset. As a quality measure for a given feature subset, the error rate of the nearest neighbour classifier estimated with the leaving-one-out method is used. With the optimal feature subset, feed forward neural networks with error backpropagation as learning function are trained. Several neural networks with different network topologies and learning parameters were trained to compare the classification performance. A three layer network with one hidden layer consisting of 20 units has shown the best performance of all considered neural networks with a classification error rate of 13.4%. The best results using the nearest neighbour classifier achieved an error rate of 6.8%.

Dermoscopy of Acral Melanoma: A Multicenter Study on Behalf of the International Dermoscopy Society

Background: Most studies on dermoscopy of acral lesions were conducted in Asian populations. In this study, we analyzed these features in a predominantly Caucasian population. Objective: Estimate the prevalence of dermoscopic features in acral lesions, and assess their level of agreement between observers. Methods: In this retrospective multicenter study, 167 acral lesions (66 melanomas) were evaluated for 13 dermoscopic patterns by 26 physicians, via a secured Internet platform. Results: Parallel furrow pattern, bizarre pattern, and diffuse pigmentation with variable shades of brown had the highest prevalence. The agreement for lesion patterns between physicians was variable. Agreement was dependent on the level of diagnostic difficulty. Conclusion: Lesions with a diameter >1 cm were more likely to be melanoma. We found as well that a benign pattern can be seen in parts of melanomas. For this reason one should evaluate an acral lesion for the presence of malignant patterns first.

Hautkrebsscreening in Deutschland

ZusammenfassungAuf der Basis des Hautkrebsscreening-Modells für Deutschland wird eine kritische Stellungnahme zu der Hautkrebsepidemiologie, der klinischen Untersuchung und den Untersuchungsintervallen dargelegt. Bei steigender Zahl der Hautkrebsfälle und wahrscheinlich sinkender Facharztzahl wird eine grundsätzliche und pragmatische Planung für die weitere fachärztliche Ausbildung und Tätigkeit bei zunehmendem dermatoonkologischem Versorgungsbedarf der alternden Bevölkerung erforderlich sein. Dabei sollte die Dermatoskopie ein fester Bestandteil in der Früherkennung von Hautkrebs und seinen Vorstufen sowie für die Vermeidung unnötiger Exzisionen benigner Hauttumoren sein. Eine Optimierung des Verhältnisses von exzidierten malignen zu benignen Hauttumoren sollte als wichtiges Qualitätskriterium angestrebt werden.AbstractBased on the skin cancer screening model of Germany a critical statement is presented about skin cancer epidemiology, the total body examination and time intervals. The number of skin cancer cases will increase and the number of dermatologists will probably decrease; thus a fundamental and pragmatic strategy is required for further education and planning to comply with the increased dermato-oncological demand of an aging population. Hereby dermoscopy should be a basic diagnostic tool for the early recognition of skin cancer and precursors as well as to avoid unnecessary excisions of benign skin lesions. The excision ratio between malignant and benign skin tumours should be optimized.Based on the skin cancer screening model of Germany a critical statement is presented about skin cancer epidemiology, the total body examination and time intervals. The number of skin cancer cases will increase and the number of dermatologists will probably decrease; thus a fundamental and pragmatic strategy is required for further education and planning to comply with the increased dermato-oncological demand of an aging population. Hereby dermoscopy should be a basic diagnostic tool for the early recognition of skin cancer and precursors as well as to avoid unnecessary excisions of benign skin lesions. The excision ratio between malignant and benign skin tumours should be optimized.

Dermatoskopie der Nägel

Pigmented and nonpigmented nail abnormalities often represent a challenge for clinicians because many, and sometimes potentially life-threatening differential diagnoses must be taken into consideration. Although many details of nail diseases can already be assessed with the naked eye, dermoscopy opens up a second microscopic level of inspection, which can be very useful for the diagnostic process. In the last 20 years dermoscopy has made rapid progress in the further development of criteria for the early recognition of melanoma. In addition, the use of dermoscopy has been extended to the examination of cutaneous adnexa, such as hairs (trichoscopy) and nails (onychoscopy). Many, sometimes highly specific criteria for the dermoscopic assessment of nail diseases have been described in a series of recently published articles. This review article provides important diagnostic aids for a well-founded dermoscopic assessment of nail diseases.

Quantitative surface topography as a tool in the differential diagnosis between melanoma and naevus.

Background/aims: The mainstays of the clinical diagnosis of melanoma are asymmetry, border irregularity, color variegation, and a diameter >6 mm, and any major progress in diagnostic accuracy will probably be related to the development of additional criteria. Such independent criteria might arise from the study of the geometry of the tumour surface, because this quality has been substantially disregarded until now. Our work is aimed at utilizing the surface topography for the differential diagnosis between malignant melanoma and naevocytic naevus.