Dermoscopy for the pediatric dermatologist part III: dermoscopy of melanocytic lesions

Domain shifts in dermoscopic skin cancer datasets: Evaluation of essential limitations for clinical translation

The limited ability of Convolutional Neural Networks to generalize to images from previously unseen domains is a major limitation, in particular, for safety-critical clinical tasks such as dermoscopic skin cancer classification. In order to translate CNN-based applications into the clinic, it is essential that they are able to adapt to domain shifts. Such new conditions can arise through the use of different image acquisition systems or varying lighting conditions. In dermoscopy, shifts can also occur as a change in patient age or occurence of rare lesion localizations (e.g. palms). These are not prominently represented in most training datasets and can therefore lead to a decrease in performance. In order to verify the generalizability of classification models in real world clinical settings it is crucial to have access to data which mimics such domain shifts. To our knowledge no dermoscopic image dataset exists where such domain shifts are properly described and quantified. We therefore grouped publicly available images from ISIC archive based on their metadata (e.g. acquisition location, lesion localization, patient age) to generate meaningful domains. To verify that these domains are in fact distinct, we used multiple quantification measures to estimate the presence and intensity of domain shifts. Additionally, we analyzed the performance on these domains with and without an unsupervised domain adaptation technique. We observed that in most of our grouped domains, domain shifts in fact exist. Based on our results, we believe these datasets to be helpful for testing the generalization capabilities of dermoscopic skin cancer classifiers.

Lumps and bumps: What not to miss

The evaluation of pediatric patients with subcutaneous nodules remains a diagnostic challenge. Pediatric dermatologists are regularly confronted with patients who have a nonspecific nodule. Though most masses that require evaluation are ultimately benign, the possibility of a more aggressive process, including borderline or malignant neoplasms, underscores the pivotal role of the pediatric dermatologist in recognizing these lesions. The aim of this review is to provide an overview of lumps and bumps that are important to recognize to prevent delay in diagnosis or treatment of a serious underlying condition. Clinical clues that may lead the pediatric dermatologist to have a higher index of suspicion for more aggressive lesions are reviewed. Suggestions for evaluation and workup, as well as tips for the difficult to discern lesion, are proposed.

Spitzoid proliferative nodules arising in a congenital melanocytic naevus: A case report with clinical, dermoscopic and histologic correlation

Proliferative nodules (PNs) are benign nodular proliferation of melanocytes occurring within congenital melanocytic naevi (CMN). Differential diagnosis between PN and melanoma is challenging for clinicians and pathologists. We describe the case of a 9-month-old boy who developed multiple nodules arising in a medium-sized CMN. Clinically, pink papules were observed, with dotted vessels on dermoscopy, suggesting spitzoid PN. On histopathological examination, the dermoscopic findings correlated with the vertical vessels of a spitzoid PN. Dermoscopy could be a useful tool to differentiate PN from melanoma. However, further studies describing the dermoscopic features of the different PN subtypes are needed. Histopathology remains the gold standard for definitive diagnosis aided by ancillary molecular tests such as fluorescence in situ hybridization or comparative genomic hybridization.

Melanocytic nevi on the hyponychium with dermoscopic features of longitudinal brush pigmentation in children

The dermoscopic features of longitudinally aligned pigmentation on the hyponychium were previously described in pediatric patients with longitudinal melanonychia. We report four cases of biopsy-proven acral melanocytic nevi on the hyponychium with a longitudinal brush pigmentation (LBP) pattern in dermoscopy. This LBP pattern on the hyponychium may be a counterpart of the fibrillar pattern of acral melanocytic nevi. Therefore, the LBP pattern in dermoscopy may provide a useful clue for distinguishing benign melanocytic nevi from melanoma in pediatric patients.

A practical review of dermoscopy for pediatric dermatology part I: Melanocytic growths

The value of dermoscopy in the detection of skin cancer is well established. Less is published on the utility of dermoscopy in the evaluation of pediatric skin disease. Our review (in two parts) aims to serve as an update on pediatric dermoscopy and to provide readers with a practical application for the use of dermoscopy in pediatric dermatology clinics. In part I, we propose a dermoscopy algorithm for pediatric skin disease and melanocytic growths, and in part II, we address vascular growths, common skin infections, and inflammatory conditions for which dermoscopy is valuable.

Paediatric melanoma: clinical update, genetic basis, and advances in diagnosis

Paediatric melanoma is rare and challenging to diagnose. The three subtypes are Spitzoid melanoma, melanoma arising in a congenital melanocytic nevus, and conventional (also known as adult-type) melanoma. Spitzoid melanomas have characteristic histopathological and genomic aberrations. Despite frequent involvement of the sentinel lymph nodes, most cases have an uneventful clinical course. Among congenital nevi, the risk of melanoma varies by projected size in adulthood, with the greatest risk in large or giant nevi. The clinical course is generally aggressive and accounts for most melanoma-related deaths in childhood. In conventional melanoma, superficial spreading and nodular melanoma account for most cases, with risk factors and presentation largely similar to adult disease. In this Review, we discuss advances in histological diagnosis using adjunctive molecular assays, and summarise the genetic basis of paediatric melanoma.

Dermoscopy pathology correlation in melanoma

Dermoscopy is a widely used technique whose role in the clinical (and preoperative) diagnosis of melanocytic and non-melanocytic skin lesions has been well established in recent years. The aim of this paper is to clarify the correlations between the "local" dermoscopic findings in melanoma and the underlying histology, in order to help clinicians in routine practice.

Dermoscopic patterns of melanocytic nevi in children and adolescents: a cross-sectional study

Background

Childhood is a dynamic period regarding nevogenesis. Dermoscopy is a noninvasive technique, recommended for the evaluation of pigmented cutaneous lesions.

Objectives

The purpose of this study was to describe the structures and dermoscopic patterns of melanocytic nevi observed in children and adolescents.

Methods

Dermoscopy with photographic documentation was used for nevi located on the face, trunk, and extremities of 38 patients aged from one to 16 years examined at the Pediatric Dermatology Outpatient Clinic of the Federal University of São Paulo.

Results

The study included 201 skin lesions that were diagnosed as nevi during clinic examination. Upon evaluation of the global dermoscopic pattern of the lesions, the most frequently observed nevi were reticular (39.0%), followed by homogeneous (23.9%) and globular nevi (16.4%). During evaluation of the dermoscopic structures, according to the body site, the pigment network was the most observed in the extremities.

Study limitations

A limitation to be considered is that the inclusion of small or new lesions may hinder the differentiation between dots and globules.

Conclusions

In our study, the most observed pattern was reticular. There was a difference in the predominance of structures dependent on the anatomical location.

Evolution of Spitz Nevi

BACKGROUND/OBJECTIVES

Spitz nevi are melanocytic lesions with clinical, dermoscopic, and histopathologic presentations that may resemble those of melanoma. The evolution of Spitz nevi is a well-known feature. The objectives of this study were to investigate the clinical and dermoscopic features of Spitz nevi and define their evolution.

METHODS

A retrospective observational study was performed and 70 Spitz nevi were analyzed using clinical and dermoscopic examination.

RESULTS

Seventy patients were included in the study. The most common dermoscopic pattern was globular (n = 35 [50%]) followed by starburst (n = 24 [34.3%]), reticular (n = 8 [11.4%]), and homogeneous (n = 3 [4.3%]). Follow-up data were available for 27 of 70 patients. Of these, 21 demonstrated evolution on the follow-up images. A stable pattern (no evolution) was noted in 6 of 27 lesions. The patients who exhibited evolution were younger on average than the stable group (p = 0.04).

CONCLUSION

Based on our study, the most common biologic behavior for Spitz nevi is evolution. Although no significant differences were observed in other clinical features, the inverse relationship between evolution and age is important to consider when attempting to differentiate Spitz nevus from melanoma.

Dermoscopic Features of Small, Medium, and Large-Sized Congenital Melanocytic Nevi

BACKGROUND

Congenital melanocytic nevi (CMN) are present at birth. It is well known that the presence of large-sized congenital nevus in early life could predict a major risk of developing melanoma.

OBJECTIVE

To investigate the clinical and dermoscopic features of the CMN, to search for and highlight any differences between small-sized, medium-sized, large-sized CMN.

METHODS

A nonrandomized observational study was performed. A total of 108 melanocytic nevi were analysed by clinical and dermoscopic examination.

RESULTS

Of the subjects, 57.4% were aged less than 16 years, 42.6% were aged 16 and more. Of the nevi, 26 had reticular pattern (24.1%), 35 had globular pattern (32.4%), 13 had reticular-globular pattern (12.0%), 16 had homogeneous pattern (14.8%), 6 had reticular-homogeneous pattern (5.6%), 2 had globular-homogeneous pattern (1.9%), 7 had cobblestone pattern (6.5%), 3 had reticular patchy pattern (2.8%). Atypical dots and globules, focal hypopigmentation and perifollicular hypopigmentation are the most common dermoscopic features of CMN. The rarest dermoscopic feature is the blue-whitish veil.

CONCLUSION

Most of the dermoscopic features related with dysplastic nevi up to the present, such as atypical dots and globules, focal hypopigmentation, perifollicular hypopigmentation were observed in CMN, in our study. Congenital nevus and dysplastic nevi may share the same dermoscopic features, therefore it is important to know it is found at birth or not.

Spitz Nevi and Other Spitzoid Neoplasms in Children: Overview of Incidence Data and Diagnostic Criteria

Spitz nevi are benign melanocytic neoplasms characterized by epithelioid or spindle melanocytes or both. In some rare cases their presentation overlaps with the clinical and histopathologic features of malignant melanoma, so a differential diagnosis can be difficult to make. Intermediate forms between Spitz nevi and malignant melanoma, with unpredictable behavior, have been called atypical Spitz tumors. A literature search was performed to review the clinical, dermoscopic, genetic, and histopathologic aspects of spitzoid tumors. Spitz nevi mainly occur in children, with no predilection for sex, and in young women. Common sites are the head and lower arms, where Spitz nevi present as pink nodules or hyperpigmented plaques. Spitzoid lesions may have diverse dermoscopic patterns: vascular, starburst, globular, atypical, reticular, negative homogeneous, or targetoid. The management of spitzoid lesions can be invasive or conservative; surgical excision is usually reserved for those with doubtful features, whereas clinical and dermoscopic follow-up is preferred for typical pediatric Spitz nevi. The role of sentinel lymph node biopsy in atypical Spitz tumors is debated. Immunohistochemistry and new molecular techniques such as comparative genomic hybridization, polymerase chain reaction, and fluorescence in situ hybridization offer new diagnostic perspectives, investigating genetic alterations that are specific for malignant melanoma or for Spitz nevi.

Dermoscopy of Melanomas on the Trunk and Extremities in Asians

The incidence of melanoma among the Asian population is lower compared to that among the Western European population. These populations differed in their most common histopathologic subtypes, acral lentiginous melanoma being the most common in the Asian population. Although the dermoscopic features of the melanomas on the acral skin have been thoroughly investigated in the Asian population, studies concerning the dermoscopic patterns of melanomas on the non-acral skin have been scarce. The aim of this study was to investigate the dermoscopic patterns of melanomas on the trunk and extremities in the Asian population. To achieve this, we evaluated the dermoscopic patterns of 22 primary melanomas diagnosed at two university hospitals in Korea. In addition, 100 benign melanocytic lesions were included as the control group for comparative analysis. A P value less than 0.05 was regarded as statistically significant. Melanoma-associated dermoscopic features such as asymmetry (odds ratio [OR], 30.00), multicolor pattern (OR, 30.12), blotches (OR, 13.50), blue white veils (OR, 15.75), atypical pigment networks (OR, 9.71), irregular peripheral streaks (OR, 6.30), atypical vascular patterns (OR, 11.50), ulcers (OR, 15.83), atypical dots/globules (OR, 3.15), shiny white lines (OR, 5.88), and regression structures (OR, 7.06) were more commonly observed in patients with melanomas than in patients of the control group. The mean dermoscopic scores obtained on the 7-point checklist, revised 7-point checklist, 3-point checklist, ABCD rule, and CASH algorithm were 5.36, 3.41, 2.05, 6.89, and 9.68, respectively, in the primary melanomas, and 1.33, 0.93, 0.46, 2.45, and 3.60, respectively, in the control group (all, P < 0.001). The present study showed that melanoma-related dermoscopic patterns were common in Asian patients. Dermoscopy is a reliable diagnostic tool for the melanomas of the trunk and extremities in the Asian populations.

Spitzoid melanoma of childhood: a case series and review

Spitzoid melanomas (SM) and atypical Spitz tumors (AST) are rare pediatric neoplasms. We performed a retrospective, single-institution review and report our institutional experience. We identified 10 patients (median age: 12.5 years). A sentinel node biopsy (SNB) was performed in 8/10 (80%) patients, and interestingly 7/8 (87.5%) were found to be positive for malignant cells. A complete regional lymphadenectomy was performed in all SNB-positive patients, but only 2/8 (25%) were found to have additional lymph node spread. Adjuvant therapy was administered in 5/8 SLNB-positive and 2/2 (100%) regional LN-positive cases. All patients had excellent long-term outcomes (100% survival). This report highlights the excellent outcomes associated with SNB + pediatric SM and AST.

Natural history of atypical and equivocal melanocytic lesions in children: an observational study of 19 cases

Digital dermoscopy follow-up helps to identify patterns of change typical of common atypical nevi and early melanoma and improves the follow-up of patients with atypical nevi. We report the morphologic changes observed over time in 19 atypical or equivocal acquired melanocytic nevi that underwent dermoscopic follow-up. Two observers retrospectively examined digitalized dermoscopic images of 19 atypical melanocytic nevi from 15 children and young adults (median age 12 years, range 3-26 years). The images were assessed for global dermoscopic patterns at baseline and after a median 25-month (range 6-138 mos) follow-up. Ten (52.6%) nevi changed and nine (47.4%) retained a stable dermoscopic pattern. Of the 10 changing lesions, 2 of 4 homogeneous nevi evolved into a reticular pattern and 2 into a mixed pattern; 1 of 2 nevi with a mixed pattern evolved into a homogeneous nevus and 1 into a regressing nevus; 1 of 2 nevi with "other" patterns, such as negative pigment network and peppering throughout the lesion, evolved into a mixed nevus and 1 into a regressing nevus; 1 globular nevus evolved into a mixed pattern; and 1 starburst nevus evolved into a homogeneous nevus. The most striking results of our study were that atypical nevi can evolve into common nevi or they can regress, as documented by long-term dermoscopic follow-up. In children and young adults, dermoscopic follow-up of atypical nevi might be a valid alternative to surgical excision and enables us to achieve new insights into the natural history of these nevi.