REVIEW 3 major objections 6 minor 32 references
Melanoma Detection with Uncertainty Quantification
T0 review · 3 major / 6 minor · reviewed 2026-08-12 · deepseek-v4-flash
Pith's one-line read By training on merged public datasets and rejecting uncertain predictions, this paper pushes melanoma detection accuracy from 93.2% to 97.8% while cutting misdiagnoses by over 40.5%.
desk verdict A useful benchmark and public toolkit, but the misdiagnosis-reduction claim lacks the random-rejection control needed to support it. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The central mechanism is Shannon entropy of the softmax probability vector, $H(X) = -\sum_i p_i \log p_i$, used as an uncertainty score. Predictions whose entropy exceeds a per-model threshold are rejected as 'Uncertain' and referred to a human expert; the thresholds are chosen on the validation set by minimizing the Expected Calibration Error and Brier score, and only the remaining confident predictions are evaluated. Empirically, rejecting up to 20% of low-confidence predictions improves accuracy.
What would settle it
Run the same pipeline on an independent clinical cohort with a different acquisition protocol, and check whether the validation-tuned threshold rejects a large fraction of true melanomas or whether expert review of rejected images fails to recover the classifier's missed melanomas; either observation would refute the claim that uncertainty rejection reduces misdiagnoses.
Extended reading notes
Core claim
The central claim is that uncertainty-based rejection, applied to softmax classifiers trained on combined public datasets, substantially improves melanoma detection while also improving calibration. After calibrating models and rejecting the most uncertain predictions, accuracy on the ISIC2017, ISIC2018, 7-point criteria, and Kaggle test sets reaches as high as 97.8%, up from 93.2%, with large gains in precision and sensitivity and a reduction in misdiagnoses of over 40.5%. The paper also finds that combining multiple datasets improves both classification and calibration, and that shallower networks are often better calibrated than deeper ones.
Load-bearing premise
The reported gains assume that a rejection threshold tuned on a validation set transfers to the test distribution, and that measuring accuracy only on the retained, non-rejected samples—with rejected cases referred to an expert—is a fair measure of real diagnostic improvement.
Editorial extensions
If this is right
- Any softmax classifier can be augmented with a third 'Uncertain' output without retraining, by thresholding the entropy of its probability vector.
- Training on merged datasets improves calibration as well as accuracy, so confidence scores from multi-source training can be taken more literally.
- Shallower networks such as EfficientNet and VGG often show better calibration than deeper networks, which matters for deployment where trust in confidence is critical.
- Entropy-based rejection reduces both false positives and false negatives, including most false negatives on the Kaggle test set, which is the clinically dangerous error direction.
Reading between the lines
- The threshold-selection strategy could be stress-tested under distribution shift by tuning on one dataset and applying the fixed threshold to a dataset collected with a different camera or population; the paper does not report this experiment.
- A prospective study that tracks whether dermatologists confirm the 'Uncertain' referrals would be the natural validation step for clinical adoption.
- The same merge-and-reject pipeline could transfer to other imbalanced medical imaging tasks such as mammography, a direction the authors list as future work.
- The reported 40.5% misdiagnosis reduction is computed on retained samples only; a full accounting that treats rejected samples as diagnosed-by-expert could change the headline number.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper describes a framework for melanoma detection that merges up to ten public dermoscopic datasets, trains 24 CNN architectures under a unified protocol (1,296 dataset/model combinations), calibrates classifiers using ECE and Brier score, and rejects predictions whose Shannon entropy exceeds a model-specific threshold tuned on validation data. On four external test sets (ISIC2017, ISIC2018, 7-point criteria, Kaggle), the selected top models achieve accuracy up to 93.2% before rejection and 97.8% after rejection, with a claimed reduction in misdiagnoses of over 40.5%. The authors also release code, data, and a client-side web interface.
Significance. If the improvements are real, the paper provides a useful and reproducible empirical study of uncertainty-based deferral for melanoma classification, with several commendable strengths: the 1,296-experiment sweep over public datasets, external test-set evaluation, calibration metrics, a public repository, and a deployed web interface. However, the central quantitative claims currently rest on (i) post hoc selection of best models, (ii) retained-only metrics without coverage or a random-rejection control, and (iii) single-seed results with no intervals. These are fixable, and the work would be valuable after those controls are added.
major comments (3)
- [Section 3.3, Table 1, Fig. 5] The central claim that uncertainty-based rejection causes the reported improvements is not yet established. Thresholds are tuned on validation data, but Table 1 reports 'after rejection' precision, sensitivity, specificity, F1, accuracy, and AUC only on the retained test samples, with no count or fraction of rejected samples given for any row. Since removing difficult samples mechanically raises accuracy on the remainder, the gains (e.g., 93.2% to 97.8% on Kaggle) are also fully consistent with a selection effect that would occur even for random rejection. The authors should report the retained-sample size/coverage for every configuration and compare against a random-rejection baseline at matched coverage, with confidence intervals. They should also specify how rejected cases are counted in the misdiagnosis-reduction claim in Fig. 5: if rejected cases are referred to an expert, the end-to-end misdiagnosis rate depends on referral accuracy, which is not modeled.
- [Section 4 and Table 1] The paper's headline numbers are selected post hoc. Figure 1 states that 1,296 experiments were run, and Table 1 shows only 'top-performing models' per test set, apparently chosen by precision on the same test sets. This selection invalidates the strongest point estimates as estimates of framework performance. The authors should report the full distribution (mean, median, range) of metrics across all 1,296 runs, or use a fixed model set, or split test sets so that model selection and evaluation are separate. Without this, the claim that the framework 'achieves' 97.8% accuracy is an optimistic maximum, not an expected performance.
- [Sections 3.2–4] No statistical uncertainty is quantified. All experiments appear to be single runs; no random seeds, standard deviations, or confidence intervals are reported. Given stochastic SGD training and small test sets (7-point criteria has a few hundred images), differences of several percentage points between before/after rejection may not be significant. Please report at least three training seeds (or bootstrap confidence intervals) for the key metrics in Table 1 and Fig. 5.
minor comments (6)
- [Section 2.3, Eq. (1)] Please specify the base of the logarithm and the normalization. The claim that H(X) lies in [0,1] holds for binary classification only if log base 2 is used, but the equation uses an unspecified log.
- [Table 3, ISIC2018 row] The entry 'VGG19 [19]' should cite reference [21] (VGG), not [19] (DenseNet).
- [Section 4] The sentence 'ResNet152 improves precision by at least 10% points' is contradicted by Table 1, e.g., the ISIC2017 row [A–D,I,J] shows 82.0% to 87.0%, a gain of only 5 percentage points. Please rephrase to 'up to more than 10 percentage points' or report per-row gains.
- [Figure 5] The caption says 'A plot comparing false diagnoses before and after applying uncertainty-based rejection across benchmarks,' but the y-axis label and legend are difficult to read. Please clarify what quantity is plotted (absolute counts or normalized rates) and for which model(s) and test sets.
- [Section 2.4] The description of the 'Uncertain' class is brief. Please clarify whether the system outputs a three-way decision ('Melanoma,' 'Non-Melanoma,' 'Don't Know') and how that interacts with the binary softmax probabilities.
- [Table 1] Several cells have inconsistent spacing around slashes (e.g., '91.5% / 91.8%' versus '84.8% /94.1%') and some numbers are missing spaces. Please reformat for readability.
Circularity Check
No significant circularity: the uncertainty-rejection thresholds are tuned on validation sets and performance is measured on external test sets, with no load-bearing self-citation or definitional reduction.
full rationale
This paper is an empirical benchmark study rather than a derivation from a first-principles model, so the circularity patterns of self-definition, renamed known results, or imported uniqueness theorems do not apply. The only tunable component in the uncertainty-rejection pipeline is the rejection threshold, and Section 3.3 states that it is selected on validation sets: "We calculate ECE and Brier scores while varying the threshold to minimize their average for each model. After this dynamic rejection, we re-evaluate the remaining samples and compare them to the originals." The post-rejection accuracy in Table 1 is then reported on held-out external test sets (ISIC2017, ISIC2018, 7-point criteria, Kaggle), so the improvement is not forced by construction from the threshold choice. The entropy formula (Eq. 1), ECE (Eq. 2), and Brier score (Eq. 3) are standard external definitions, not redefinitions of the outcome. Reference [11] is used only for the web-application architecture and is not load-bearing for the central claim. The absence of a random-rejection baseline is a legitimate experimental-design concern, since the reported gains could partly reflect a selection effect rather than the informativeness of the entropy score, but that is a correctness risk, not circularity under the stated criteria.
Assumptions & free parameters
free parameters (1)
- uncertainty rejection threshold per model =
Ranges from 0.08 to 0.2 across reported models (Table 1)
assumptions (4)
- standard math Shannon entropy H(X) = -sum p_i log p_i is an appropriate measure of predictive uncertainty for a softmax classifier.
- domain assumption Resizing all images to 224x224 pixels and mapping all non-melanoma labels to a single class preserves enough information for binary melanoma detection.
- domain assumption High-entropy softmax predictions are more likely to be misclassifications, so rejecting them reduces errors.
- ad hoc to paper A rejection threshold tuned on the validation set generalizes to the test distribution for each model.
Cite this review
Pith. "Pith review of Melanoma Detection with Uncertainty Quantification." pith.science (2026). https://pith.science/paper/4XVYG3X2
@misc{pith2026241110322,
author = {Pith},
title = {Pith review of: Melanoma Detection with Uncertainty Quantification},
year = {2026},
howpublished = {\url{https://pith.science/paper/4XVYG3X2}},
note = {Machine review of arXiv:2411.10322}
}
read the original abstract
Early detection of melanoma is crucial for improving survival rates. Current detection tools often utilize data-driven machine learning methods but often overlook the full integration of multiple datasets. We combine publicly available datasets to enhance data diversity, allowing numerous experiments to train and evaluate various classifiers. We then calibrate them to minimize misdiagnoses by incorporating uncertainty quantification. Our experiments on benchmark datasets show accuracies of up to 93.2% before and 97.8% after applying uncertainty-based rejection, leading to a reduction in misdiagnoses by over 40.5%. Our code and data are publicly available, and a web-based interface for quick melanoma detection of user-supplied images is also provided.
Figures
Reference graph
Works this paper leans on
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[1]
INTRODUCTION Melanoma is a severe skin cancer responsible for around 55,500 deaths annually [1]. Deep Neural Networks (DNNs) are effective in melanoma detection, but their evaluation lacks standardization, complicating comparisons. For exam- ple, DNN-based melanoma classification using segmented features [2] has shown promising results on the ISIC’16 [3] ...
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[2]
Melanoma Detection with Uncertainty Quantification
METHODS 2.1. Input Most public melanoma datasets include images and associ- ated metadata about skin lesions. Image sizes range from 147x147 to 3096x3096 pixels, with class counts from 2 to 9, consistently including melanoma labels. These datasets vary in structure—some use a single folder with a separate CSV for labels and splits, while others organize b...
work page Pith review arXiv 2024
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[3]
EXPERIMENTAL SETUP 3.1. Datasets and Preprocessing We utilize publicly available skin disease datasets [3, 4, 6, 12, 13, 14, 15, 16, 17, 18] and evaluate our experiments using pro- vided test sets [4, 6, 15, 18]. When a validation set is not pro- vided, we split the training set into an 80:20 ratio for creating a validation set. These datasets include a “...
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[4]
RESULTS Performance Before Rejection. Classification performance is ranked by precision, following the ISIC challenge [3]. DenseNet201 and ResNet152 achieve the best results, with Fig. 4. Calibration curves of ResNet50 as a demonstration. Left: Single dataset (ISIC’20). Right: Combined datasets (ISIC’16, ISIC’17, ISIC’18, MEDNODE, Kaggle). Table 2. Leader...
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[5]
CONCLUSIONS We propose a melanoma framework integrating unified train- ing and testing with uncertainty-based rejection to enhance classification and calibration while reducing misdiagnoses. Future plans include collecting real-time diagnosis data from dermatologists and using Generative Adversarial Networks (GAN) for iterative retraining. We also aim to ...
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[6]
ACKNOWLEDGMENTS This material is based, in part, upon work supported by the Defense Logistics Agency (DLA) and the Advanced Re- search Projects Agency for Health (ARPA-H) under Contract Number SP4701-23-C-0073. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the...
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COMPLIANCE WITH ETHICAL STANDARDS All datasets used in this study were anonymized and publicly available, for which no ethical approval was required
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