ALADIN (Acne Lesion And Density INdex): a novel tool for automatic acne severity assessment
Published in Skin Health and Disease (Oxford Academic), this peer-reviewed study introduces ALADIN (Acne Lesion And Density INdex), an artificial intelligence-driven tool that combines inflammatory lesion count and spatial density from facial images to produce reproducible, interpretable acne severity scores aligned with the Investigator Global Assessment (IGA) scale.
Medela A, Sabater A, Hernández Montilla I, Mac Carthy T, Aguilar A, Fernández G, Martorell A, Vera Carretero S, Balboni C, Martín Alcalde J, Ramírez Bellver JL, Martin-Gorgojo A, Rodriguez Jiménez P, López Estebaranz JL. ALADIN (Acne Lesion And Density INdex): a novel tool for automatic acne severity assessment. Skin Health and Disease. 2026. https://doi.org/10.1093/skinhd/vzag062
ALADIN was validated retrospectively against IGA and Global Acne Grading System (GAGS) scores annotated by expert dermatologists, using both a public dataset of predominantly severe cases and a private dataset of mild-to-moderate cases. Its performance aligned well with the interobserver correlation of dermatologists, supporting its use as a standardized, explainable grading tool.
Figure 2: The ALADIN acne lesion density calculator
Panel (a): inflammatory lesions detected on a facial image. Panel (b): each detected lesion is expanded into an influence area proportional to its size. Panel (c): overlapping influence areas are measured to capture how clustered the lesions are, combining lesion count and spatial density into a single, reproducible severity signal.
Results
Table 2: Performance of ALADIN (Acne Lesion And Density INdex) with regard to Global Acne Grading System scores
| Model | AcneSeverity-V1 Spearman | AcneSeverity-V1 Pearson | AcneSeverity-V2 Spearman | AcneSeverity-V2 Pearson |
|---|---|---|---|---|
| ALADIN | 0.34 | 0.32 | 0.52 | 0.43 |
| Dermatologists | 0.44 | 0.44 | 0.33 | 0.44 |
Correlation of ALADIN scores with expert-annotated Global Acne Grading System (GAGS) scores, reported for two model versions (AcneSeverity-V1 and AcneSeverity-V2) using Spearman and Pearson coefficients. The dermatologist row reflects the interobserver correlation between expert raters, used as the reference benchmark. ALADIN's correlation with GAGS approaches and, for AcneSeverity-V2, matches the agreement observed between dermatologists themselves.
ALADIN demonstrates consistent performance and excellent interpretability. Compared with manual scoring systems, it provides a streamlined, data-driven alternative capable of minimizing observer bias. When integrated into a medical device software, it can further aid in standardizing acne severity assessment and enhance patient monitoring.