Can You See It? Diagnostic Blind Spots in Pigmented Skin

Background: Plastic surgery relies heavily on the visual assessment of skin and soft tissues, yet most diagnostic descriptors, clinical scales, and imaging technologies have been developed and validated predominantly in lighter-skinned populations. This introduces systematic diagnostic uncertainty for patients with darker skin tones, with implications for burns, scars, pressure injury, superficial infection, and flap monitoring. This review synthesizes the current evidence on the performance of diagnostic modalities across the Fitzpatrick spectrum and identifies priority areas for research and training. Methods: A narrative literature review was conducted across PubMed and Scopus from inception to October 2024. Controlled vocabulary and free-text terms covering skin tone, surgical conditions, and diagnostic techniques were combined with Boolean and adjacency operators. Studies were included if they explicitly addressed darker skin tones in the context of clinical assessment or monitoring. Evidence was appraised according to the Oxford Center for Evidence-Based Medicine Levels of Evidence. Results: Findings are synthesized across 4 modality layers: clinical assessment, color photography, superficial imaging, and deep imaging with artificial intelligence. Clinical descriptors such as erythema, blanching, and capillary refill demonstrated reduced reliability in darker skin across all clinical conditions examined. Of the 15 commonly used scar scales, only 3 were validated in pigmented skin. Color photography was limited by melanin-related attenuation of dynamic range. Sub-epidermal moisture assessment had the strongest evidence base for superficial pathology, with validated performance in dark skin and meta-analytic reductions in stage 2 pressure injury. Deep imaging modalities (SFDI, HSI, NIRS, photoacoustic imaging) were susceptible to melanin-related signal distortion, whereas ICG angiography and near-infrared laser Doppler were relatively robust. Patients with Fitzpatrick type VI skin had a flap loss rate of 85.7% after vascular compromise, compared with 21.4% in type I. Artificial intelligence tools showed stratified performance by skin tone, underscoring the need for diverse training data sets. Conclusions: Current assessment methods in plastic surgery are insufficiently validated for patients with darker skin, contributing to diagnostic delay and inequitable outcomes. Objective, skin-tone-inclusive diagnostic tools, stratified validation across Fitzpatrick types, and updated clinical training are urgently needed to close this evidence gap.