Dermatoscopic patterns of cutaneous metastases: A multicentre cross-sectional study of the International Dermoscopy Society.

BACKGROUND: The detection of cutaneous metastases (CMs) from various primary tumours represents a diagnostic challenge. OBJECTIVES: Our aim was to evaluate the general characteristics and dermatoscopic features of CMs from different primary tumours. METHODS: Retrospective, multicentre, descriptive, cross-sectional study of biopsy-proven CMs. RESULTS: We included 583 patients (247 females, median age: 64 years, 25%-75% percentiles: 54-74 years) with 632 CMs, of which 52.2% (n = 330) were local, and 26.7% (n = 169) were distant. The most common primary tumours were melanomas (n = 474) and breast cancer (n = 59). Most non-melanoma CMs were non-pigmented (n = 151, 95.6%). Of 169 distant metastases, 54 (32.0%) appeared on the head and neck region. On dermatoscopy, pigmented melanoma metastases were frequently structureless blue (63.6%, n = 201), while amelanotic metastases were typified by linear serpentine vessels and a white structureless pattern. No significant difference was found between amelanotic melanoma metastases and CMs of other primary tumours. CONCLUSIONS: The head and neck area is a common site for distant CMs. Our study confirms that most pigmented melanoma metastasis are structureless blue on dermatoscopy and may mimic blue nevi. Amelanotic metastases are typified by linear serpentine vessels and a white structureless pattern, regardless of the primary tumour.

The Association between the Morphology of Vessels in Primary Cutaneous Melanoma on Dermoscopy, with the Breslow Index, the Presence of Ulceration, and the Dermoscopic Signs of Extensive Regression.

BACKGROUND: Dermoscopy is a noninvasive technique for the diagnosis of cutaneous melanoma that may play a role in the preoperative assessment of melanoma thickness. With this technique, several vascular morphologies have been identified. The objectives of this study are to study the presence and morphology of blood vessels in a series of primary melanomas and to investigate whether they are related to the Breslow index, the presence of ulceration, and extensive dermoscopic regression. METHODS: This cross-sectional study included nonacral, nonfacial primary melanomas, with dermoscopic images from four hospitals in Spain. The outcome variables were the Breslow index, the presence of dermoscopic ulceration, and an extensive dermoscopic regression. The explicative variables were the presence of vessels, the predominant vessel in the most raised area of the melanoma, and the presence of polymorphous vessels. To study the association between qualitative variables and the Breslow index, we used the Kruskal-Wallis test or Mann-Whitney U test and between qualitative variables, the χ2 test. To study the magnitude of the association, the ORs (95% CI) were calculated. RESULTS: A set of 516 images from melanomas was collected. The presence of vessels was associated with thicker melanomas (p < 0.001). Vessel type was associated with different Breslow indexes (p < 0.001) (arborizing, linear irregular, corkscrew, glomerular, hairpin, and dotted vessels (in decreasing order)). The polymorphous vessels were associated with thicker melanomas (p < 0.001). Linear irregular vessels were associated with ulceration (OR = 10.6, 95% CI 4.9-24.0, p < 0.001) and dotted vessels with the presence of extensive dermoscopic regression (OR = 2.7, 95% CI 1.4-5.2, p = 0.003). The main limitations of this study were the high selection of cases and the difficulty in identifying vessels in pigmented melanomas by dermoscopy. CONCLUSIONS: The morphology of blood vessels in cutaneous melanoma on dermoscopy is associated with the Breslow index, the presence of ulceration, and extensive dermoscopic regression.

Dermoscopy of haemosiderotic/aneurysmal dermatofibroma: A morphological study of 110 cases.

BACKGROUND: Haemosiderotic and aneurysmal dermatofibromas are uncommon and frequently misdiagnosed lesions, which can be considered as different histopathological stages of the same tumour. A dermoscopic diagnosis testing accuracy has not been performed for these tumours to date. OBJECTIVES: To determine the diagnostic significance of dermoscopic structures and patterns associated with haemosiderotic/ aneurysmal dermatofibromas in a large series. METHODS: Dermoscopic images of histopathologically proven cases of 110 haemosiderotic/ aneurysmal dermatofibromas and 501 other tumours were collected. The frequency, sensitivity, specificity, positive predictive value and negative predictive value of the dermoscopic structures and patterns associated with these lesions were calculated. RESULTS: Haemosiderotic/ aneurysmal dermatofibromas are mostly symmetric lesions (86.5%), and a prominent homogeneous area was present in 100% of them. The presence of vascular structures was very common (86.4%), and dotted vessels were predominant (58.2%). Shiny white structures were seen in 85.5% of lesions, while a peripheral delicate pigment network was present in 69.1%. The most significant pattern was the one composed of a prominent homogeneous area and peripheral delicate pigment network, which showed a specificity of 100% with a relatively good sensitivity (69.1%). All the patterns containing a peripheral delicate pigment network showed very good specificities, positive predictive values and negative predictive values. Those patterns without a peripheral delicate pigment network showed the highest sensitivities, but they showed a significant overlap with other tumours, mainly with melanoma. CONCLUSIONS: Dermoscopy is helpful in improving the diagnostic accuracy of haemosiderotic/ aneurysmal dermatofibromas. However, there is a considerable dermoscopic overlap between these tumours and melanoma, specifically when the peripheral delicate pigment network is absent.

Dermatoscopy of nodular/plaque-type primary cutaneous T- and B-cell lymphomas: A retrospective comparative study with pseudolymphomas and tumoral/inflammatory mimickers by the International Dermoscopy Society.

BACKGROUND: Limited data on dermatoscopy of nodular/plaque-type T-/B-cell primary cutaneous lymphomas (PCLs) is available. OBJECTIVE: To describe dermatoscopic features of nodular/plaque-type PCLs, comparing them with those of clinical mimickers (pseudolymphomas, tumors, and inflammatory lesions) and investigating possible differences according to histologic subtypes. METHODS: Participants were invited to join this retrospective, multicenter case-control study by submitting histologically/immunohistochemically confirmed instances of nodular/plaque-type PCLs and controls. Standardized assessments of the dermatoscopic images and comparative analyses were performed. RESULTS: A total of 261 lesions were included (121 PCLs and 140 controls). Orange structureless areas were the strongest PCL dermatoscopic predictor on multivariate analysis compared with tumors and noninfiltrative inflammatory dermatoses. On the other hand, a positive association was found between PCLs and either unfocused linear vessels with branches or focal white structureless areas compared with infiltrative inflammatory dermatoses, whereas white lines were predictive of PCLs over pseudolymphomas. Differences in the vascular pattern were also seen between B- and T-cell PCLs and among B-cell PCL subtypes. LIMITATIONS: Retrospective design and the lack of a dermatoscopic-pathologic correlation analysis. CONCLUSION: Nodular/plaque-type PCLs display dermatoscopic clues, which may partially vary according to histologic subtype and whose diagnostic relevance depends on the considered clinical differential diagnoses.

Dermoscopy of inflamed seborrheic keratosis: A great mimic of malignancy.

BACKGROUND: Clinical and dermoscopic recognition of seborrheic keratoses (SKs) is often straightforward, and biopsy might not be required. However, inflamed SKs (iSKs) can pose a diagnostic challenge. Dermoscopic features of iSKs have not yet been evaluated to date. OBJECTIVES: To assess the diagnostic ability of a group of dermatologists to diagnose iSKs by dermoscopy. To evaluate the dermoscopic findings of a long series of inflamed seborrheic keratoses. METHODS: Clinical and dermoscopic images of 100 difficult-to-diagnose skin tumours, including 29 iSKs, were presented to 33 clinicians (24 dermatologists and 9 dermatology residents), who were blinded to the diagnosis. The dermoscopic features of a series of 219 iSKs were retrospectively analysed. RESULTS: iSKs were correctly identified in a 37.6% of cases. Classic dermoscopic criteria were present in only 47% of iSKs. The most frequent dermoscopic feature in iSKs was the presence of vascularization (91.3%), but only a 44.5% showed predominance of hairpin vessels. A bluish hue was observed in 18.3% of lesions. Seven dermoscopic patterns were identified, based on the dermoscopic similarity to other tumours: seborrheic keratosis-like (28.8%); squamous cell carcinoma-like (25.6%); melanoma-like (17.8%); keratoacanthoma-like (6.8%); basal cell carcinoma-like (5.9%); verruca vulgaris-like (5.9%); nevus-like (2.3%). CONCLUSIONS: The diagnosis of iSKs can be challenging even with dermoscopy. They may behave as authentic mimics of other cutaneous tumours, including squamous cell carcinoma or melanoma. For this reason, histopathological examination should be mandatory in these cases.

The Usefulness of Dermoscopy for the Recognition of Malignant Collision Tumors.

BACKGROUND: Preoperative diagnosis of malignant collision tumors (MCT) is extremely difficult. The value of dermoscopy to improve the correct detection of these tumors has not been previously studied. This study aims to evaluate the diagnostic accuracy of MCT with and without dermoscopy and to describe the dermoscopic features of a large series of MCT. METHODS: Dermoscopic images of 161 MCT were evaluated. Clinical and dermoscopic images of histopathologically proven MCT intermingled with other tumors were randomly presented to clinicians with different levels of experience, blinded to the diagnosis and objective of the study. The clinical and dermoscopic diagnostic accuracies were measured separately. RESULTS: A total of 161 histopathologically proven cases of MCT were collected. The most frequent MCT was basal cell carcinoma-seborrheic keratosis collision tumor (CT; 37.9%), followed by basal cell carcinoma-melanocytic nevus CT (19.9%), and melanoma-seborrheic keratosis CT (6.8%). Diagnostic accuracy among experts on dermoscopy was 71.4%. The study included 119 participants. The percentage of correct diagnoses was 8% by naked eye examination and 36.4% by dermoscopy (p < 0.001). The presence of the malignant component in the cases of MCT was not recognizable in 19.1% of cases by naked eye examination and in 11.8% of cases by dermoscopy (p < 0.001). CONCLUSIONS: The diagnosis of MCT can be assisted and clarified by dermoscopy. However, many of these lesions manifest complex morphologies and continue to be challenging, even for experts on dermoscopy. Atypical, uncertain, or non-classifiable lesions still need a complete excision for the final diagnosis.

Clear Cell Proliferations of the Skin: A Histopathologic Review.

ABSTRACT: Cutaneous clear cell proliferations encompass a heterogenous group of several primary cutaneous neoplasms and metastatic tumors with different histogenesis. Many of these clear cell proliferations may seem strikingly similar under the microscope resulting in challenging diagnosis. In many of these clear cell lesions, the reason for the clear or pale appearance of proliferating cells is unknown, whereas in other ones, this clear cell appearance is due to intracytoplasmic accumulation of glycogen, mucin, or lipid. Artifacts of tissue processing and degenerative phenomenon may also be responsible for the clear cell appearance of proliferating cells. Awareness of the histopathologic findings as well as histochemical and immunohistochemical techniques are crucial to the accurate diagnosis. This review details the histopathologic features of clear cell cutaneous proliferations, classifying them according their type of differentiation and paying special attention to the histopathologic differential diagnosis among them.

Incidence of Melanoma in Catalonia, Spain, Is Rapidly Increasing in the Elderly Population. A Multicentric Cohort Study.

The incidence of melanoma has been increasing worldwide during recent decades. The objective of the study was to analyse the trends in incidence for in situ and invasive melanoma in the Spanish region of Catalonia during the period of 2008-2017. We designed a cross-sectional study with an age-period-cohort analysis of melanoma patient data from the Network of Melanoma Centres in Catalonia. Our database covered a population of over seven million and included a total of 8626 patients with incident melanoma. The main outcome measures were crude and age-standardised incidence rates to the European 2013 standard population. Joinpoint regression models were used to evaluate the population trends. We observed an increase in the age-standardised incidence rate (per 100,000 population) of all melanoma subtypes from 11.56 in 2008 to 13.78 in 2017 with an average annual percent change (AAPC) of 3.5%. This incidence increase was seen exclusively in the older population. Moreover, the stratified analysis showed a statistically significant increase in the age-standardised incidence rate for invasive (AAPC 2.1%) and in situ melanoma (AAPC 6.5%). In conclusion, the incidence of melanoma has continued to increase in the elderly population over recent decades, with a rapidly increasing trend of in situ melanomas and the lentigo maligna subtype.

Heterogeneity in the linear shiny white structures in melanomas seen with polarized light according to histopathological association: Cross-sectional observational study in 118 cutaneous melanomas.

Polarized dermoscopy enables visualization of linear shiny white structures in melanomas, thought to be due to the existence of fibrosis in the dermis. Our objective was to establish the existence of two types of linear shiny white structures and assess their association with different histological structures. We performed a cross-sectional study including all non-acral, non-facial melanomas from our hospital with linear shiny white structures. The outcome variable was the type of linear shiny white structures: shiny white streaks and white strands. We evaluated their association with explanatory variables that may affect the reflectance of melanomas and Breslow index. We used χ2 statistics and also calculated the sensitivity and specificity of each linear shiny white structure to predict those variables. We detected linear shiny white structures in 118 melanomas. Regarding shiny white streaks, we only found a statistically significant positive relationship with fibrosis in the papillary dermis. Regarding white strands, we found statistically significant and positive relationships with hyperkeratosis, Breslow index of 0.8 mm or more and acanthosis. Sensitivity and specificity study revealed that the presence of shiny white streaks was the most sensitive (81.7%) and specific (72.3%) for fibrosis in the papillary dermis, and presence of white strands was the most sensitive (91.1%) and specific (85.7%) for hyperkeratosis.

Increasing incidence of lentigo maligna and lentigo maligna melanoma in Catalonia.

BACKGROUND: Recent epidemiological studies suggest that past data where superficial spreading melanoma was by far the most common subtype of melanoma may not reflect current patterns of sun exposure or other risk factors more involved in other subtypes of melanoma as lentigo maligna (LM) or lentigo maligna melanoma (LMM). METHODS: In order to measure the current situation in our country, all cases of LM and LMM diagnosed in 23 hospitals in Catalonia, from 2000 to 2007, were recorded. RESULTS: Although for the global period LM/LMM represented only 8.4% of cases, an increasing trend in this percentage was observed throughout the study period (from 6.9% [27 cases] in 2000 to 13.1% [94 cases] in 2007). Also, an increasing incidence of LM/LMM was observed, especially in chronically sun-exposed areas (85.5% involving the head and neck region). During the 8 years of the registry, the mean Breslow thickness of LMM remained stable. However, the increase in the number of LM (in situ) cases was significantly higher than the increase of the invasive ones. CONCLUSIONS: An important observation from this data is that aging of population and current sun exposure patterns could keep increasing the incidence of LM/LMM, which may become an important public healthcare problem, over the other histological subtypes. In order to establish primary or secondary preventive measures to the LM/LMM risk-population, it is imperative to highlight the importance of chronic sun damage as a melanoma risk factor, and not only sunburn, most commonly addressed in melanoma prevention campaigns.

Dermoscopy of lipidised dermatofibroma: A morphological study of 13 cases.

BACKGROUND/OBJECTIVES: The aim of this study was to evaluate the morphological findings of lipidised dermatofibromas under dermoscopic observation. METHODS: Dermoscopic examination of 13 cases of lipidised dermatofibromas was performed to evaluate specific dermoscopic criteria and patterns. RESULTS: The most frequently occurring dermoscopic features were as follows: (i) A yellowish homogenous pigmentation in all cases (100%); this pigmentation was total in 30.7%; (ii) White structures were seen in 46.1%, most of them were central white networks (38.4%); (iii) Pigment network was observed in 53.8%, most of them were peripheral delicate pigment networks (38.4%), but two cases showed an atypical pigment network; (iv) The presence of vascular structures was common (10 cases, 77%); (v) Regarding to dermoscopic patterns, five lipidised dermatofibromas (38.4%) showed a total yellowish homogeneous pattern; 38.4% an atypical pattern and 23.2% a 'central white network + peripheral delicate pigment network' pattern. CONCLUSIONS: The dermoscopic recognition of a total yellowish homogeneous area or a yellowish colouration in the context of a dermatofibroma can be proposed to help suspecting a lipidised dermatofibroma.

Dermoscopy of Adnexal Tumors.

Cutaneous adnexal tumors include lesions with apocrine, eccrine, follicular, sebaceous, and mixed differentiation. Most are benign and sporadic, although malignant forms are occasionally observed and some cases develop in the setting of inherited syndromes. These tumors often cause immense diagnostic difficulty. Dermoscopy is a noninvasive technique that has greatly improved the diagnostic accuracy of different skin lesions, including these tumors. We provide a review of the literature on the dermoscopic structures and patterns associated with adnexal tumors. Most patterns associated with this kind of tumor are nonspecific and are observed in other nonadnexal tumors, especially in basal cell carcinomas.

Dermoscopy of chondrodermatitis nodularis helicis.

Chondrodermatitis nodularis helicis (CNH) is a benign auricular disease whose differentiation with nonpigmented tumors is mandatory. Clinical characteristics of CNH are well known, but there is no information about the dermoscopic features that could help differentiate CNH from squamous cell carcinoma and other non-melanoma skin cancers. To describe the dermoscopic appearance of CNH and to formulate a differential diagnostic model, we conducted  a retrospective, single center, observational dermoscopic study on a sample of 189 biopsy-proven lesions: 25 CNH; 26 squamous cell carcinomas; 62 basal cell carcinomas and 76 other benign and malignant tumors. Univariate and multivariate analyses were conducted by logistic regression. The most significant dermoscopic finding for CNH was a peculiar global configuration (daisy pattern), consisting of white thick lines, radially arranged, converging to a central rounded yellow/brown clod (an erosion covered by keratin or sero-crust). This pattern achieved 92 and 98% of specificity for discriminating CNH with squamous cell carcinoma and basal cell carcinoma, respectively. In conclusion, dermoscopy is valuable for the diagnosis of CNH as a first screening tool because of a consistent global dermoscopic configuration (daisy pattern), consisting of radially arranged white thick lines surrounding a central rounded yellow/brown clod.

Dermoscopy of arteriovenous tumour: A morphological study of 39 cases.

BACKGROUND/OBJECTIVES: Arteriovenous tumour is a distinct, benign, acquired vascular lesion that can be misdiagnosed. METHODS: A dermoscopic examination of 39 cases of arteriovenous tumours collected from four Spanish hospitals was performed to evaluate specific dermoscopic criteria and patterns. RESULTS: The most common structures found were vascular, 95% of cases (37/39); 90% (35/39) were non-arborising telangiectasia. All the lesions except two (95%) had a homogeneous pigmentation background that was red in 30 cases (77%), bluish-red in three (8%), brown in two (5%) and blue or multicoloured in one case each. Lacunae were seen in only three cases (8%). Non-arborising telangiectasia on a reddish background was identified in 72% of cases. CONCLUSIONS: Dermoscopy is helpful in improving the diagnosis of arteriovenous tumours and allows the observer to differentiate them from other cutaneous lesions such as other vascular tumours, basal cell carcinomas and melanomas.

Dermoscopy of lymphangioma circumscriptum: A morphological study of 45 cases.

BACKGROUND/OBJECTIVES: The dermoscopy of lymphangioma circumscriptum, also known as superficial lymphatic malformation, remains to be clarified. METHODS: Digital dermoscopic images of 45 histopathologically confirmed cases of lymphangioma circumscriptum collected from nine hospitals in Spain, Italy and Turkey were evaluated for the presence of dermoscopic structures and patterns. RESULTS: Our study shows that the most common structure found in lymphangioma circumscriptum was the presence of lacunae (89% of cases). The latter were red or dark-coloured in 18 cases (45%), yellowish or whitish in 14 cases (35%) and multicoloured in eight cases (20%). The second most common dermoscopic structure was the presence of vascular structures, which were found in 82% of cases, followed by white lines (47%), the hypopyon sign or two-tone lacunae (42%) and scales (7%). CONCLUSIONS: Dermoscopy is useful in improving the diagnosis of lymphangioma circumscriptum with characteristic structures and patterns and could assist in elucidating the presence of blood in lymphatic channels.

Dermoscopic Clues for Diagnosing Melanomas That Resemble Seborrheic Keratosis.

Importance: Melanomas that clinically mimic seborrheic keratosis (SK) can delay diagnosis and adequate treatment. However, little is known about the value of dermoscopy in recognizing these difficult-to-diagnose melanomas. Objective: To describe the dermoscopic features of SK-like melanomas to understand their clinical morphology. Design, Setting, and Participants: This observational retrospective study used 134 clinical and dermoscopic images of histopathologically proven melanomas in 134 patients treated in 9 skin cancer centers in Spain, France, Italy, and Austria. Without knowledge that the definite diagnosis for all the lesions was melanoma, 2 dermoscopy-trained observers evaluated the clinical descriptions and 48 dermoscopic features (including all melanocytic and nonmelanocytic criteria) of all 134 images and classified each dermoscopically as SK or not SK. The total dermoscopy score and the 7-point checklist score were assessed. Images of the lesions and patient data were collected from July 15, 2013, through July 31, 2014. Main Outcomes and Measures: Frequencies of specific morphologic patterns of (clinically and dermoscopically) SK-like melanomas, patient demographics, and interobserver agreement of criteria were evaluated. Results: Of the 134 cases collected from 72 men and 61 women, all of whom were white and who had a mean (SD) age of 55.6 (17.5) years, 110 (82.1%) revealed dermoscopic features suggestive of melanoma, including pigment network (74 [55.2%]), blue-white veil (72 [53.7%]), globules and dots (68 [50.7%]), pseudopods or streaks (47 [35.1%]), and blue-black sign (43 [32.3%]). The remaining 24 cases (17.9%) were considered likely SKs, even by dermoscopy. Overall, lesions showed a scaly and hyperkeratotic surface (45 [33.6%]), yellowish keratin (42 [31.3%]), comedo-like openings (41 [30.5%]), and milia-like cysts (30 [22.4%]). The entire sample achieved a mean (SD) total dermoscopy score of 4.7 (1.6) and a 7-point checklist score of 4.4 (2.3), while dermoscopically SK-like melanomas achieved a total dermoscopy score of only 4.2 (1.3) and a 7-point checklist score of 2.0 (1.9), both in the range of benignity. The most helpful criteria in correctly diagnosing SK-like melanomas were the presence of blue-white veil, pseudopods or streaks, and pigment network. Multivariate analysis found only the blue-black sign to be significantly associated with a correct diagnosis, while hyperkeratosis and fissures and ridges were independent risk markers of dermoscopically SK-like melanomas. Conclusions and Relevance: Seborrheic keratosis-like melanomas can be dermoscopically challenging, but the presence of the blue-black sign, pigment network, pseudopods or streaks, and/or blue-white veil, despite the presence of other SK features, allows the correct diagnosis of most of the difficult melanoma cases.

Dermoscopy of Nodular Hidradenoma, a Great Masquerader: A Morphological Study of 28 Cases.

BACKGROUND: Nodular hidradenoma is an uncommon, benign, adnexal neoplasm of apocrine origin which is a clinical simulator of other tumours. OBJECTIVE: The aim of this study was to evaluate the morphological findings of a large series of nodular hidradenomas under dermoscopic observation. METHODS: Dermoscopic examination of 28 cases of nodular hidradenomas was performed to evaluate specific dermoscopic criteria and patterns. RESULTS: The most frequently occurring dermoscopic features were: (1) in 96.4% of cases, a homogeneous area that covered the lesion partially or totally, the colour of which was pinkish in 46.4% of cases, bluish in 28.6%, red-blue in 14.3%, and brownish in 10.7%; (2) white structures were found in 89.3% of cases; (3) in 82.1% of cases, vascular structures were also observed, especially arborising telangiectasias (39.3%) and polymorphous atypical vessels (28.6%). CONCLUSION: Nodular hidradenomas represent a dermoscopic pitfall, being difficult to differentiate clinically and dermoscopically from basal cell carcinomas and melanomas.

Dermoscopy of Targetoid Hemosiderotic Hemangioma: A Morphological Study of 35 Cases.

BACKGROUND: Targetoid hemosiderotic hemangioma is an uncommon, vascular, benign solitary lesion of lymphatic origin that can be misdiagnosed as other tumors including melanomas. OBJECTIVES: To evaluate the dermoscopic features of a large series of targetoid hemosiderotic hemangiomas. METHODS: Digital dermoscopic images of 35 histopathologically confirmed cases of targetoid hemosiderotic hemangiomas collected from 7 hospitals in Spain and Italy were evaluated for the presence of dermoscopic structures and patterns. RESULTS: The results of our study reveal that the presence of central red and dark lacunae and a peripheral circular reddish-violaceous homogeneous area is the most common dermoscopic pattern in targetoid hemosiderotic hemangioma (71.4%). The targetoid hemosiderotic hemangiomas of our study were correctly diagnosed in 77% of cases. CONCLUSION: Dermoscopy is helpful in improving the diagnosis of targetoid hemosiderotic hemangioma. However, attention must be paid to those cases that dermoscopically may show nontargetoid patterns, which often mimic other lesions, including melanoma.

Clinical and dermoscopic features of atypical Spitz tumors: A multicenter, retrospective, case-control study.

BACKGROUND: Few studies have described the clinical and dermoscopic features of atypical Spitz tumors. OBJECTIVE: We sought to describe the clinical and dermoscopic features of a series of atypical Spitz tumors as compared with those of conventional Spitz nevi. METHODS: This was a multicenter, retrospective, case-control study, analyzing the clinical and dermoscopic characteristics of 55 atypical Spitz tumors and 110 Spitz nevi that were excised and diagnosed histopathologically. RESULTS: The majority of atypical Spitz tumors presented clinically as a plaque or nodule, dermoscopically typified by a multicomponent or nonspecific pattern. A proportion of lesions (16.4%) exhibited the typical nonpigmented Spitzoid pattern of dotted vessels and white lines under dermoscopy. Nodularity, ulceration, linear vessels, polymorphic vessels, white lines, and blue-white veil were associated with atypical Spitz tumors by univariate analysis, but only nodularity and white lines remained significant after multivariate analysis. In contrast, a pigmented typical Spitzoid pattern was a potent predictor of Spitz nevi, associated with 6.5-fold increased probability. LIMITATIONS: Differentiation from Spitzoid melanoma and other nonmelanocytic lesions was not investigated. CONCLUSION: Atypical Spitz tumors are polymorphic melanocytic proliferations with a nodular clinical appearance. Dermoscopically they demonstrate a multicomponent and nonspecific pattern. A typical nonpigmented Spitzoid pattern on dermoscopy (with dotted vessels and white lines) does not exclude atypical Spitz tumors.