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We present a case report of a 3.5 mm diameter superficial spreading melanoma on the upper back of a 27-year-old woman, signed out as Clark level 2, Breslow thickness 0.2 mm with regression to 0.45 mm. The patient, with Fitzpatrick type 1 skin and minimal actinic damage, had presented for a routine skin check with no previous history of skin cancers. At the age of 17 she had received chemotherapy and radiotherapy for Ewing’s sarcoma of the right hip with pulmonary metastases. The skin lesion was assessed as dermatoscopically symmetrical and was not predicted as a melanoma by any algorithmic method. The provisional diagnosis of melanoma was made on the basis that this lesion was completely different in dermatoscopic pattern to her other nevi, a dermatoscopic “ugly duckling” lesion. We draw attention to the recently established link between defects in the STAG2 gene and Ewing’s sarcoma, glioblastoma and melanoma.

We present a case of an early invasive melanoma (Breslow thickness 0.25 mm), 1.6 mm in diameter on the arm of a 38-year-old woman. She was under surveillance due to having multiple (>100) nevi, and the melanoma was assessed as a new lesion by the examining doctor. Clinically the lesion was hyperpigmented compared with surrounding nevi and dermatoscopically it had a clue of pseudopods/lines radial, but they were arranged in an arguably symmetrical circumferential pattern around a structureless blue-gray center. Generally melanomas are expected to be dermatoscopically asymmetrical, but we believe that this case illustrates the fact that small melanomas may be recognized by clues such as pseudopods/lines radial and dermatoscopic gray even when they have not yet developed unequivocal asymmetry.

Background Very small pigmented lesions may represent an important diagnostic challenge to the clinician. Objectives The aim of the present study was to establish the diagnostic value, in terms of sensitivity and specificity, of both clinical and dermoscopic examinations in a population of patients with unselected consecutive pigmented lesions with a maximum clinical diameter of 3 mm. Patients and methods Two hundred and four consecutive patients bearing 206 pigmented skin lesions with a maximum diameter of 3 mm were seen and operated on. Twenty-three of these lesions were melanomas. Each lesion was subjected to both clinical and dermoscopic evaluation before surgery. The results were expressed in terms of sensitivity and specificity of both kinds of evaluation. Results Clinical evaluation produced a diagnostic sensitivity of 43% and a specificity of 91%. Dermoscopy resulted in a sensitivity of 83% and in a specificity of 69%. The comparison between the sensitivity values of the two diagnostic methods showed a significant difference ( P < 0.01). A high value of significance was also obtained comparing the respective specificity values ( P < 0.001). Conclusions Detection of very small melanomas is feasible by accurate visual inspection. Dermoscopy appears to be an important aid to diagnosis, provided that physicians are aware of this type of lesion and maintain the index of suspicion at a high level. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to develop a validated machine learning model to diagnose small choroidal melanoma., Design: This is a cohort study., Subjects Participants And/or Controls: The training data included 123 patients diagnosed as small choroidal melanocytic tumor (5.0-16.0 mm in largest basal diameter and 1.0 mm-2.5 mm in height; Collaborative Ocular Melanoma Study criteria). Those diagnosed as melanoma ( n = 61) had either documented growth or pathologic confirmation. Sixty-two patients with stable lesions classified as choroidal nevus were used as negative controls. The external validation dataset included 240 patients managed at a different tertiary clinic, also with small choroidal melanocytic tumor, observed for malignant growth., Methods: In the training data, lasso logistic regression was used to select variables for inclusion in the final model for the association with melanoma versus choroidal nevus. Internal and external validation was performed to assess model performance., Main Outcome Measures: The main outcome measure is the predicted probability of small choroidal melanoma., Results: Distance to optic disc ≥3 mm and drusen were associated with decreased odds of melanoma, whereas male versus female sex, increased height, subretinal fluid, and orange pigment were associated with increased odds of choroidal melanoma. The area under the receiver operating characteristic "discrimination value" for this model was 0.880. The top four variables that were most frequently selected for inclusion in the model on internal validation, implying their importance as predictors of melanoma, were subretinal fluid, height, distance to optic disc, and orange pigment. When tested against the validation data, the prediction model could distinguish between choroidal nevus and melanoma with a high discrimination of 0.861. The final prediction model was converted into an online calculator to generate predicted probability of melanoma., Conclusions: To minimize diagnostic uncertainty, a machine learning-based diagnostic prediction calculator can be readily applied for decision-making and counseling patients with small choroidal melanoma., Competing Interests: Arun D. Singh: Editor-in-Chief of Ocular Oncology and Pathology. Reported financial activities outside the submitted work: Aura Biosciences (stock options), IsoAid LLC (consultancy), Immunocore (consultancy), Isoaid (consultancy), and Eckert and Zeigler (consultancy). Other authors have no conflicts of interest to declare., (Copyright © 2021 by S. Karger AG, Basel.)