Regressing seborrheic keratosis - clinically and dermoscopically mimicking a regressing melanoma

The diagnosis of seborrheic keratosis is a clinical diagnosis. In a certain percentage of cases, differential diagnosis between seborrheic keratosis and malignant melanoma is difficult. We describe a case of regressing seborrheic keratosis simulating malignant melanoma. Clinical, dermoscopic and histopathologic examinations were performed for the occurrence of an asymmetric, irregularly demarcated, irregularly pigmented lesion measuring 1.3 x 1.5 cm on the right part of the abdomen in a 76-year-old male Caucasian. In order not to miss melanoma, the excision and histopathologic examination of the lesion with peppering is essential.     

Differentiation of melanoma from benign mimics using the relative‐color method

Background: Previous studies have successfully classified 86% of malignant melanomas using a relative‐color segmentation method, by feature extraction from photographic images in the automatic identification of skin tumors. These studies were extended by applying the relative‐color method to dermoscopic images of melanoma grouped with melanoma in situ and clark nevus lesions in dermoscopic images allow more control over lighting variations, which contribute to lesion misclassification. Dermoscopic images then enable a more detailed examination of the structure of skin lesions, provide much more structural detail within lesions, and contain visual information that cannot be seen in photographic images. This present work extends the previous studies by applying relative‐color feature extraction to dermoscopic images to differentiate among melanoma, seborrheic keratoses and Reed/Spitz nevi. Objective: To develop a method for automatically differentiating among malignant melanoma, seborrheic keratoses and Reed/Spitz nevi, using digitized, color, dermoscopic images. Methods: Images underwent preprocessing, tumor segmentation, feature extraction and tumor classification. The relative‐color method was used in the segmentation stage. Classification was accomplished by taking the inner products of model tumor feature vectors with test‐image tumor vectors followed by the nearest‐neighbor classification method. Results: The classification rates of melanoma, seborrheic keratoses and Reed/Spitz nevi images mixed together, were 60%, 58.3% and 80%, respectively. Classification of melanoma and Reed/Spitz nevi mixed, were 70% and 90%, respectively. Classification rates were the best when melanoma was being differentiated from seborrheic keratoses. These rates were 100% and 88.9%, respectively. Conclusion: Dermoscopic rather than photographic images were preprocessed, using a hair‐removal technique. They were then converted to relative‐color images, which were segmented using the principal components transform and median split, followed by morphological filtering. After processing, the multi‐dimensional tumor feature space described herein was used to differentiate the tumors. The high success rates for differentiating seborrheic keratoses from melanoma show that the use of dermoscopic images has a strong promise in enabling prescreening, as well as automated assistance and significant improvement in tumor diagnosis in clinics.     

Eccrine porocarcinoma arising in a seborrheic keratosis evaluated with dermoscopy and treated with Mohs' technique

A 78-year-old white woman returned for a routine 6-month skin cancer examination. She had a history of actinic keratosis and multiple basal cell carcinomas. She had no personal or family history of dysplastic nevi or melanoma. The patient was asymptomatic and unaware of any new or changing skin lesions. The patient had multiple lentigines, hemangiomas, and actinic and seborrheic keratoses on all sun-exposed areas. There were no less than 10 seborrheic keratoses on the right mid-back, and one was found to have a 1-cm, reddish nodule asymmetrically located within it (Figs 1 and 2). A clear papule on the left preauricular area was found on biopsy to be a basal cell carcinoma. The nodule on the back was still present 1 month later and it was felt that further evaluation was indicated. As melanoma has been reported to develop in seborrheic keratoses, we decided to examine the lesion using digital dermoscopy. With digital dermoscopy, a well-demarcated reddish nodule was asymmetrically located within a brown lesion. It blanched significantly with pressure. Within the nodule, there were dotted and irregular linear vessels (atypical vascular pattern; also known as polymorphous vascular pattern) and regular-appearing brown dots. Surrounding the reddish nodule, there were pale and pigmented, comedo-like openings, fissures, and ridges (brain-like appearance). Some of the follicular openings appeared to be within the wall of the nodule (Figs 3 and 4). Comedo-like openings, fissures, and ridges are primary dermoscopic criteria for the diagnosis of a seborrheic keratosis; however, the vascular pattern seen has not been reported in seborrheic keratosis. Due to the patient's age and the rarity of significant pathology arising in a seborrheic keratosis, a shave biopsy was performed. To our surprise, the specimen was interpreted by an experienced dermatopathologist as a well-differentiated eccrine porocarcinoma. Due to the high local recurrence rate and metastatic potential of this carcinoma, the patient was referred for Mohs' surgery. Both the basal cell carcinoma and the eccrine porocarcinoma were excised in one stage. A metastatic work-up was negative and the patient appears to be doing well.     

日光性雀斑样痣、脂溢性角化病及扁平苔藓样角化病皮肤镜特征专家共识

【摘要】 日光性雀斑样痣、脂溢性角化病及扁平苔藓样角化病是常见的良性表皮增生性疾病,其皮肤镜特征对于明确诊断、与其他皮肤肿瘤相鉴别、避免不必要的活检和手术以及动态监测皮损变化等都有一定帮助。本共识对这3种疾病的皮肤镜特征进行了总结。日光性雀斑样痣的皮肤镜特征主要为皮损边界清晰、虫蚀状边缘、模糊的色素网、指纹模式、棕色均质模式、假性网络。脂溢性角化病的皮肤镜特征主要为皮损边界清晰、粟粒样囊肿、粉刺样开口、脑回状模式、发夹样血管、摇晃试验中皮损整体移动。扁平苔藓样角化病的皮肤镜特征主要为胡椒粉样或颗粒模式以及周围可见日光性雀斑样痣、脂溢性角化病或光线性角化病的皮肤镜特征。     

Pigmented seborrheic keratoses of the vulva clinically mimicking a malignant melanoma: a clinical, dermoscopic-pathologic case study

The diagnosis of seborrheic keratosis is, in general, a clinical one, but in some cases, the differential diagnosis between pigmented seborrheic keratosis and malignant melanoma is difficult. Dermoscopy may improve the early diagnosis of vulvar melanoma and thus play a role in the preoperative classification of pigmented lesions at this particular site. We report the first case of a pigmented seborrheic keratosis of the vulva clinically mimicking a malignant melanoma, whose dermoscopic features have been investigated together with their pathologic correlates. Dermoscopically our case shows the absence of comedo-like openings and the presence of the pseudo-network. Dermoscopy is therefore a useful method for the differential diagnosis of pigmented lesions even in the vulva.     

Seborrheic keratosis with compound nevus, junctional nevus and basal cell carcinoma in the same lesion.

Seborrheic keratosis can be associated with different neoplasms such as basal cell carcinomas, squamous cell carcinomas and melanomas. We describe an unusual case of a man who presented with a brown plaque on his back. The clinical diagnosis was melanoma. Histopathologic examination of the lesion revealed four neoplasms: a compound nevus, a junctional nevus, a superficial basal cell carcinoma and a seborrheic keratosis. Although this association most likely represents a chance phenomenon, we discuss the possibility that the seborrheic keratosis developed from the nevus, and that subsequently the junctional nevus and the basal cell carcinoma developed from the seborrheic keratosis.     

Dermoscopy of pigmented seborrheic keratosis: a morphological study

OBJECTIVES: To describe morphological features of seborrheic keratosis as seen by dermoscopy and to investigate their prevalence. DESIGN: Prospective cohort study using macrophotography and dermoscopy for the documentation of seborrheic keratosis. SETTINGS: Seborrheic keratoses were prospectively collected in 2 sites: a private practice in Plantation, Fla (site 1), and the Department of Dermatology at the University Hospital Geneva in Switzerland (site 2). PATIENTS: A total of 203 pigmented seborrheic keratoses (from 192 patients) with complete documentation were collected (111 from site 1 and 93 from site 2). INTERVENTIONS: Screening for new morphological features of seborrheic keratosis and evaluation of all lesions for the prevalence of these criteria. MAIN OUTCOME MEASURES: Identification of new morphological criteria and evaluation of frequency. RESULTS: A total of 15 morphological dermoscopic criteria were identified. Standard criteria such as milialike cysts and comedolike openings were found in a high number of cases (135 and 144, respectively). We found network and networklike structures to be present in 94 lesions (46%). Using standard diagnostic criteria for seborrheic keratosis, 30 lesions would not have been diagnosed as such. CONCLUSIONS: The classic dermoscopic criteria for seborrheic keratosis (milialike cysts and comedolike openings) have a high prevalence but the use of additional dermoscopic criteria such as fissures, hairpin blood vessels, sharp demarcation, and moth-eaten borders improves the diagnostic accuracy. The proper identification of pigment network and networklike structures is important for the correct diagnosis.     

Comedo-like openings in melanoma

We describe a case of melanoma with the presence of comedo-like openings at dermoscopy. These structures, typical of seborrheic keratosis, represent an uncommon finding in melanoma. We emphasize the importance of searching for specific dermoscopic criteria for melanocytic lesions during the examination of a pigmented lesion, despite possible observations of characteristic structures of non-melanocytic lesions, in order to increase the accuracy in the diagnosis of melanoma.     

Clinicopathological correlation of pigmented skin lesions using dermoscopy

Dermoscopy (dermatoscopy, epiluminescence microscopy) is an additional measure for making the diagnosis of pigmented skin lesions more accurate. It enables the clinician to visualize features not discernible by the naked eye. By applying enhanced digital dermoscopy and a standardized gross pathology protocol to pigmented skin lesions, a precise clinicopathological correlation of relevant dermoscopic features can be made. Histological specimens of four pigmented skin lesions (melanoma in situ, Clark's nevus, Reed's nevus, seborrheic keratosis) were processed using a standardized gross pathology protocol and viewed along with the clinical photographs and digital dermoscopic images that were magnified and enhanced to better visualize the corresponding dermoscopic structures. Furthermore, measurements of dermoscopic structures using digital equipment were correlated with histometric findings. Our understanding of dermoscopic features, especially the broadened pigment network - a specific dermoscopic criterion for melanoma - was refined by this detailed case-by-case correlation. In addition, some not yet fully characterized dermoscopic features, such as black lamella, radial streaks, and exophytic papillary structures, were described in detail dermoscopically and histopathologically. Moreover, measurements of these dermoscopic features and the underlying histological structures were found to be similar. Linking dermoscopy more closely with cutaneous pathology may help refine the definitions and diagnostic criteria of pigmented skin lesions for dermatologists as well as dermatopathologists.     

Dysplastic nevus associated with seborrheic keratosis

Seborrheic keratosis is a common skin lesion which may coincidentally be associated melanocytic nevi. The authors describe a case of dysplastic nevus associated with seborrheic keratosis and discuss the clinical, dermoscopic, and histological findings of this association. They also discuss the association between seborrheic keratosis and other benign and malignant tumours.     

Fibroepitelioma de Pinkus. Descripción dermatoscópica de 3 casos

Fibroepithelioma of Pinkus is considered to be a rare variant of basal cell carcinoma with well-defined histopathological features.Clinical diagnosis often requires differentiation from benign lesions such as acrochordon, intradermal melanocytic nevus, neurofibroma, seborrheic keratosis, and even malignant lesions such as amelanotic melanoma. Dermoscopy of this type of lesion is not extensively described in the literature, though it usually presents certain specific characteristics that suggest the diagnosis and, therefore, an appropriate therapeutic approach.We present 3 cases of fibroepithelioma of Pinkus, describing their clinical, dermoscopic, and histopathological features.     

光线性角化病的皮肤镜特征研究进展

光线性角化病（AK）是皮肤长期暴露于日光下所引起的一种癌前病变,有发展为鳞癌的风险,皮肤镜已广泛应用于AK的诊断与鉴别诊断,其皮肤镜特征包括: 基底假网状红斑、毛囊口周围白晕、毛囊口黄色角栓等,本文对AK的皮肤镜表现及鉴别诊断进行了综述。     

Cloudy and starry milia‐like cysts: how well do they distinguish seborrheic keratoses from malignant melanomas?

Background Seborrheic keratoses are the most common skin lesions known to contain small white or yellow structures called milia‐like cysts (MLCs). Varied appearances can sometimes make it difficult to differentiate benign lesions from malignant lesions such as melanoma, the deadliest form of skin cancer found in humans. Objective The purpose of this study was to determine the statistical occurrence of MLCs in benign vs. malignant lesions. Methods A medical student with 10 months experience in examining approximately 1000 dermoscopy images and a dermoscopy‐naïve observer analysed contact non‐polarized dermoscopy images of 221 malignant melanomas and 175 seborrheic keratoses for presence of MLCs. Results The observers found two different types of MLCs present: large ones described as cloudy and smaller ones described as starry. Starry MLCs were found to be prevalent in both seborrheic keratoses and melanomas. Cloudy MLCs, however, were found to have 99.1% specificity for seborrheic keratoses among this group of seborrheic keratoses and melanomas. Conclusion Cloudy MLCs can be a useful tool for differentiating between seborrheic keratoses and melanomas.     

Seborrheic keratosislike melanoma with folliculotropism

BACKGROUND: Seborrheic keratosislike melanoma could be one of the most problematic melanoma simulators, and it may be incorrectly treated by electrocautery or cryotherapy. Dermoscopic examination of pigmented tumors improves the diagnostic accuracy in these challenging lesions. In these tumors, numerous comedolike openings are present. OBSERVATIONS: A 34-year-old man was seen for a conspicuous pigmented lesion on his back that clinically resembled a seborrheic keratosis because of the presence of multiple comedolike openings. Findings from dermoscopic examination showed distinct melanoma criteria (atypical pigmented network, asymmetric globules and dots, and a blue-whitish veil), in addition to multiple comedolike openings. Histopathological examination confirmed a peculiar melanoma variant characterized by prominent folliculotropism and minimal radial spreading. This tumor was not associated with chronic sun-damaged skin. CONCLUSION: Dermoscopy was useful in identifying a particular case of seborrheic keratosislike melanoma with folliculotropism, thus avoiding incorrect treatment.     

Seborrheic keratoses, solar lentigines, and lichenoid keratoses. Dermatoscopic features and correlation to histology and clinical signs

Evaluation of the three benign lesions discussed here form the basis for dermoscopic evaluation of other pigmented skin lesions. The features of seborrheic keratosis, including [figure: see text] the various forms of fissures, comedo-like openings, and milia-like cysts, often allow easy interpretation of seborrheic keratosis; however, similar structures are commonly associated with melanocytic neoplasms, notably congenital nevi. Understanding solar lentigo and its dermoscopy features allows for the appreciation of pigment networks common in lentiginous melanocytic nevi and melanoma. The lichenoid keratosis is the model for lichenoid inflammation elsewhere, notably in halo nevi, regressing melanoma, and other melanocytic neoplasms with significant host inflammatory reactions.     

Biopsy guided by dermoscopy in cutaneous pigmented lesion - Case report

It may be clinically difficult to differentiate early-stage melanoma from benign tumors, specially pigmented seborrheic keratosis. Dermoscopy can help; however, the findings are not always conclusive. Therefore, histopathology may be necessary for a correct diagnosis. We describe a melanocytic lesion with dubious clinic and dermoscopic findings. An incisional biopsy of a suspicious area, guided by dermoscopy, was performed to clarify the findings.     

Colour histogram analysis for melanoma discrimination in clinical images

Background: Malignant melanoma, the most deadly form of skin cancer, has a good prognosis if treated in the curable early stages. Colour provides critical discriminating information for the diagnosis of malignant melanoma.
Methods: This research introduces a three-dimensional relative colour histogram analysis technique to identify colours characteristic of melanomas and then applies these 'melanoma colours' to differentiate benign skin lesions from melanomas. The relative colour of a skin lesion is determined based on subtracting a representative colour of the surrounding skin from each lesion pixel. A colour mapping for 'melanoma colours' is determined using a training set of images. A percent melanoma colour feature, defined as the percentage of the lesion pixels that are melanoma colours, is used for discriminating melanomas from benign lesions. The technique is evaluated using a clinical image data set of 129 malignant melanomas and 129 benign lesions consisting of 40 seborrheic keratoses and 89 nevocellular nevi.
Results: Using the percent melanoma colour feature for discrimination, experimental results yield correct melanoma and benign lesion discrimination rates of 84.3 and 83.0%, respectively.
Conclusions: The results presented in this work suggest that lesion colour in clinical images is strongly related to the presence of melanoma in that lesion. However, colour information should be combined with other information in order to further reduce the false negative and false positive rates.     

Colour analysis of skin lesion regions for melanoma discrimination in clinical images

Background: Skin lesion colour is an important feature for diagnosing malignant melanoma. Colour histogram analysis over a training set of images has been used to identify colours characteristic of melanoma, i.e., melanoma colours. A percent melanoma colour feature defined as the percentage of the lesion pixels that are melanoma colours has been used as a feature to discriminate melanomas from benign lesions.
Methods: In this research, the colour histogram analysis technique is extended to evaluate skin lesion discrimination based on colour feature calculations in different regions of the skin lesion. The colour features examined include percent melanoma colour and a novel colour clustering ratio. Experiments are performed using clinical images of 129 malignant melanomas and 129 benign lesions consisting of 40 seborrheic keratoses and 89 nevocellular nevi.
Results: Experimental results show improved discrimination capability for feature calculations focused in the lesion boundary region. Specifically, correct melanoma and benign recognition rates are observed as high as 89 and 83%, respectively, for the percent melanoma colour feature computed using only the outermost, uniformly distributed 10% of the lesion's area.
Conclusions: The experimental results show for the features investigated that the region closest to the skin lesion boundary contains the greatest colour discrimination information for lesion screening. Furthermore, the percent melanoma colour feature consistently outperformed the colour clustering ratio for the different skin lesion regions examined. The clinical application of this result is that clustered colours appear to be no more significant than colours of arbitrary distribution within a lesion.     

Seborrheic Keratosis: An Acantholytic Variant

Two elderly women with seborrheic keratoses on the abdomen are reported on because of the peculiar histologic appearance characterized by prominent acantholysis. Although the basic histologic architecture was a papillomatous acanthoma corresponding to that of seborrheic keratosis, the upper portion of the lesions showed extensive acantholytic changes and dyskeratotic cells. Differentiation from seborrheic keratosis with focal acantholytic dyskeratosis, warty dyskeratoma, keratosis senilis and acantholytic squamous cell carcinoma could be made on the basis of clinical as well as histological features. Although the histogenesis is uncertain, it seems logical to propose that this is a rare variant of irritated seborrheic keratosis.     

Clonal nature of seborrheic keratosis demonstrated by using the polymorphism of the human androgen receptor locus as a marker

We evaluated the clonality of seborrheic keratoses using a polymorphism due to the random inactivation of one of two X chromosomes in females. Thirty-eight seborrheic keratoses obtained from the skin of females with polymorphism of the human androgen receptor (HUMARA) locus were examined by a fluorescent polymerase chain reaction procedure, which allowed accurate measurement of the peak intensities of each HUMARA allele. The epithelial portion of seborrheic keratosis and normal control epidermis adjacent to the seborrheic keratosis were removed by laser capture microdissection. As biopsied specimens of seborrheic keratoses contained small amounts of normal epidermis, the effect of digestion by a restriction enzyme (HhaI) recognizing the nonmethylated active sites was compared between seborrheic keratoses and normal control epidermis in only five seborrheic keratosis cases. Disappearance or significant reduction in intensity of one of two HUMARA alleles was observed after HhaI digestion in seborrheic keratoses, but not in the normal control epidermis. Although the skewing of the polymorphism was not corrected by the normal control epidermis in the remaining 33 seborrheic keratosis cases, one of two HUMARA peaks practically disappeared after HhaI digestion in 20 of 33 seborrheic keratosis cases. In total, 25 of 38 seborrheic keratoses were considered to be monoclonal. The histologic type of seborrheic keratoses did not affect clonality.