In Silico Evaluation of Nanosecond Laser Treatment of Pigmented Lesions Based on Skin Optical Properties Using a Model of Melanosome Disruption Threshold Fluence.

OBJECTIVES: This study aimed to evaluate the efficacy and safety of nanosecond laser treatment of pigmented lesions in silico using a model of melanosome disruption threshold fluence (MDTF) based on skin optical properties. METHODS: Particle size analysis and scanning electron microscopy were performed to determine the threshold fluence for melanosome disruption using a nanosecond laser. By inputting the obtained threshold fluence into the MDTF model and considering the variability in skin optical properties, irradiation parameters were calculated and compared with the results from clinical studies. RESULTS: The threshold fluences for 532 and 755 nm nanosecond laser irradiation were determined to be 3.0 and 15.0 J/cm2, respectively. In silico analysis showed that the incident fluence for moderately pigmented skin should be 1.2 times that for lightly pigmented skin, whereas it should be 50% lower than that for lightly pigmented skin to achieve the same level of energy deposition. Clinically applied fluences for moderately pigmented skin are at the low end of the calculated range of values, suggesting that the clinical fluence is chosen to minimize energy deposition in normal tissues. CONCLUSIONS: Our results showed that the MDTF model can be used to evaluate nanosecond laser treatments and provide clinical guidance on fluence settings based on laser-tissue interactions in moderately pigmented skin. The in silico method can, therefore, provide a robust and quantitative retrospective evaluation of the treatment effects that accounts for variation in irradiation parameters among patients by combining the MDTF model with the in vivo optical properties of individual skin types.

Skin Type Diversity in Skin Lesion Datasets: A Review.

Purpose of review: Skin type diversity in image datasets refers to the representation of various skin types. This diversity allows for the verification of comparable performance of a trained model across different skin types. A widespread problem in datasets involving human skin is the lack of verifiable diversity in skin types, making it difficult to evaluate whether the performance of the trained models generalizes across different skin types. For example, the diversity issues in skin lesion datasets, which are used to train deep learning-based models, often result in lower accuracy for darker skin types that are typically under-represented in these datasets. Under-representation in datasets results in lower performance in deep learning models for under-represented skin types. Recent findings: This issue has been discussed in previous works; however, the reporting of skin types, and inherent diversity, have not been fully assessed. Some works report skin types but do not attempt to assess the representation of each skin type in datasets. Others, focusing on skin lesions, identify the issue but do not measure skin type diversity in the datasets examined. Summary: Effort is needed to address these shortcomings and move towards facilitating verifiable diversity. Building on previous works in skin lesion datasets, this review explores the general issue of skin type diversity by investigating and evaluating skin lesion datasets specifically. The main contributions of this work are an evaluation of publicly available skin lesion datasets and their metadata to assess the frequency and completeness of reporting of skin type and an investigation into the diversity and representation of each skin type within these datasets. Supplementary Information: The online version contains material available at 10.1007/s13671-024-00440-0.

Effects of a skin type diversity seminar on undergraduate medical students' self-assessed competence in managing skin diseases in patients with skin of color.

BACKGROUND: Skin diseases in patients with skin of colour (Fitzpatrick skin types IV to VI) are underrepresented in dermatology training, which may lead to lower quality of care for these patients. To address this underrepresentation in medical education, a newly developed seminar on skin type diversity using an interactive teaching method was implemented in an undergraduate medical curriculum. This study examined the effects of a seminar on the self-assessed competence of medical students in managing skin conditions in patients with skin of colour. METHODS: A questionnaire survey was conducted among fourth-year undergraduate medical students at the University of Hamburg (Germany) between October 2023 and February 2024. Students' self-assessed competence was compared before and after the obligatory seminar (pre- and post-design). RESULTS: In total, 158 students participated in the survey. After the seminar, knowledge of the presentation of skin diseases in patients with skin of colour and the associated psychological burden, differences in the incidence of skin diseases in different skin types, and the ability to diagnose skin diseases in darker skin types increased. Most participants stated that they wanted to attend more courses on this topic. DISCUSSION: Appropriate courses for medical students can improve their competence in managing different skin diseases in patients with skin of colour. In the future, more attention should be paid to teaching the diversity of skin types in dermatology education.

Epidermal and dermal hydration in relation to skin color parameters.

BACKGROUND: Our goal was to investigate linkages between skin color parameters and skin hydration. Since most prior studies focused on stratum corneum hydration, we focused on epidermal and dermal hydration in relation to skin color parameters in both sexes. MATERIALS AND METHODS: Thirty adults (16 female) with an age ± SD of 24.3 ± 0.6 years participated. Three sites on both volar forearms were evaluated for melanin index (MI), erythema index (EI), Individual Typology Angle (ITA), tissue dielectric constant (TDC) values to depths of 0.5 mm (TDC0.5) and 2.5 mm (TDC2.5), and Fitzpatrick skin type (FST). RESULTS: MI and EI were highly correlated (r = 0.800, p < 0.001) with maximum differences in MI and ITA along the arm of 3% and 6.3% with no difference between arms. Male MI was greater than females (p < 0.01). Male TDC2.5 was 36.1 ± 5.4 and correlated with EI (r = 0.231, p = 0.035). Contrastingly, female TDC25 was 28.5 ± 3.6 with no correlation with EI but was correlated with MI (r = -0.301, p = 0.003). These differential patterns held true for TDC0.5. For both sexes, FST and ITA were highly correlated (r = -0.756, p < 0.001). CONCLUSIONS: The findings revealed several correlations between skin color parameters and hydration that differed between males in females in some cases. The observed correlations may indicate that melanin may differentially impact water-holding capacity between sexes and provides a future research target. Further, these initial findings also may hold significance for dermatological assessments and the customization of skincare treatments tailored to individual skin types and demographics.

Removal of black tattoos by Picosecond Q-switched Nd-YAG laser in the middle eastern skin type IV: prospective study.

Tattoo removal is considered a challenging field in cosmetic dermatology. Picosecond Q-switched Nd-YAG lasers targeting unique chromophores effectively manage this condition without serious complications. To evaluate the efficacy and safety of Picosecond Q-switched Nd-YAG laser in the treatment of black tattoos in the skin of middle eastern mostly skin type IV. The study was carried out on 20 patients with skin type IV the most common in middle eastern area with professional black tattoos. They were treated by Picosecond Nd-YAG laser (2 sessions 8 weeks apart). The percentage of improvement ranged from 20.0 to 95.0 (with a mean of 61 ± 24.6). 8 patients (40%) showed excellent improvement, 4 patients (20%) showed marked improvement, 4 patients (20%) showed moderate improvement, and 4 patients (20%) showed mild improvement. No severe side effects were detected. Picosecond Nd-YAG laser was an effective and safe technique in the treatment of professional black tattoos; with only 2 sessions most patients reached excellent to moderate response with minimal side effects.

Addressing Burn Hypertrophic Scar Symptoms Earlier: Laser Scar Revision May Begin as Early as 3-6 Months After Injury.

OBJECTIVES: Fractional ablative CO2 laser (FLSR) is used to treat hypertrophic scars (HTSs) resulting from burn injuries, which are characterized by factors, such as erythema, contracture, thickness, and symptoms of pain and itch. Traditionally, waiting a year after injury for scar maturation before starting laser treatment has been recommended; however, the potential benefits of earlier intervention have gained popularity. Still, the optimal timing for beginning laser intervention in patients with HTSs remains uncertain. This study aims to evaluate the ideal timing for the initiation of FLSR for HTSs using several qualitative and quantitative assessment measures. It was hypothesized that early intervention would lead to similar improvement trends as later intervention, however, would be more ideal due to the shortened time without symptom relief for patients. METHODS: Patients who received three or more laser treatment sessions and completed both pre- and posttreatment evaluations were included in this analysis (n = 69). FLSR treatment was administered at 4-8-week intervals. Patients starting treatment before 6 months after injury were classified as the early-stage intervention group and those beginning treatment at 6-12 months after injury were classified as the late-stage intervention group. Demographic data, including the age of patients at the time of first treatment, age of scars at the time of first treatment, biological sex, ethnicity, Fitzpatrick skin type, and use of laser-assisted drug delivery, were collected by retrospective chart review. Patients were evaluated on six subjective scales and objectively for scar stiffness with durometry. For all scales, higher scores indicate worse scars. A two-way ANOVA, Student's t-test, and Mann-Whitney U-test were used to compare scores from the pre- to posttreatment evaluations. RESULTS: There were no significant differences between the groups for any of the demographic or scar-specific variables; thus, differences in outcome can be attributed to the timing of intervention. Both groups demonstrated an improvement in scars with treatment over time (p < 0.05). Both early- and middle-stage initiation showed scar symptom improvement in five out of six scales. In the late-stage intervention, the Patient and Observer Scar Assessment Scale-Patient average score did not show improvement. In the early-stage intervention, the Vancouver Scar Scale total did not show improvement. Quantitative evaluation of scar stiffness by durometry did not show symptom improvement in either group. The Scar Comparison Scale demonstrated the greatest improvement across groups. CONCLUSION: Laser treatment led to scar improvement in at least one scale at each stage of initiation. Both intervention timelines resulted in equivalent outcomes, and early intervention should be considered when initiating FLSR treatment in burn scars to alleviate symptoms earlier.

Understanding Public Perceptions of Nipple and Scar Characteristics After Chest Wall Masculinization Surgery.

BACKGROUND: Surgical chest masculinization procedures, especially gender-affirming top surgery (GATS), are becoming increasingly prevalent in the USA. While a variety of surgical techniques have been established as both safe and effective, there is limited research examining ideal aesthetic nipple appearance and incision scar pattern. This study employs patient images to understand the public's perception on top surgery outcomes when adjusting for BMI ranges and Fitzpatrick skin types. METHODS: Images from RealSelf modified via Adobe Photoshop depicted various scar types and nipple-areolar complex (NAC) sizes/positions. A Qualtrics survey was distributed utilizing Amazon Mechanical Turk. Statistical analysis was performed through JMP Pro 17 for ordinal and categorical values, with a p value less than or equal to 0.05 statistically significant. RESULTS: A moderately sized and laterally placed NAC was preferred. A transverse scar that resembles the pectoral border between the level of the inframammary fold and pectoral insertion was deemed most masculine and aesthetic. Majority of results demonstrated that this is unaffected by Fitzpatrick skin types. Increased BMI images impacted public preferences, as a nipple placed farther from the transverse incision (p = 0.04) and a transverse scar position closer to the IMF was preferred in higher BMI patients. CONCLUSIONS: An understanding of the most popular NAC and scar choices, as well as how these factors may differ when considering a Fitzpatrick skin type or BMI categorization was attained. This validates the importance of patient-centered approach when employing surgical techniques in GATS. Future studies intend to obtain reports from actual patients considering GATS. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable.

Distance-based integration method for human skin type identification.

Although identifying human skin types is essential in dermatology, cosmetology, and facial recognition, the classification of human skin types is challenging due to the complex nature, varied characteristics, and the influence of external factors. Traditional methods for skin type identification often rely on subjective assessments, leading to inconsistent and inaccurate results. Therefore, this paper proposes a novel method named a distance-based integration method to identify skin types based on the Fitzpatrick skin scale, also known as the Fitzpatrick skin type. This study focuses on the objective distance measurement, integrated with the Fuzzy Analytic Hierarchy Process (AHP). The objective distance was utilized to determine the distance between each HEX color code for a clinical image and each target skin type. The Fuzzy AHP algorithm was employed to calculate the total score for each target class to identify human skin type. For this study, 1,022 images of human skin were used in the experiment. The results indicated that the proposed method achieved a high average accuracy of 93 %, precision of 80 %, and specificity of 96 %.

Skin Cancer Risk Is Increased by Somatic Mutations Detected Noninvasively in Healthy-Appearing Sun-Exposed Skin.

Skin cancer risk is increased by exposure to ultraviolet radiation (UVR). Because UVR exposure accumulates over time and lighter skin is more susceptible to UVR, age and skin tone are risk factors for skin cancer. However, measurements of somatic mutations in healthy-appearing skin have not been used to calculate skin cancer risk. In this study, we developed a noninvasive test that quantifies somatic mutations in healthy-appearing sun-exposed skin and applied it to a 1038-subject cohort. Somatic mutations were combined with other known skin cancer risk factors to train a model to calculate risk. The final model (DNA-Skin Cancer Assessment of Risk) was trained to predict personal history of skin cancer from age, family history, skin tone, and mutation count. The addition of mutation count significantly improved model performance (OR = 1.3, 95% confidence interval = 1.14-1.48; P = 5.3 × 10-6) and made a more significant contribution than skin tone. Calculations of skin cancer risk matched the known United States population prevalence, indicating that DNA-Skin Cancer Assessment of Risk was well-calibrated. In conclusion, somatic mutations in healthy-appearing sun-exposed skin increase skin cancer risk, and mutations capture risk information that is not accounted for by other risk factors. Clinical utility is supported by the noninvasive nature of skin sample collection through adhesive patches.

Effect of skin tone on the accuracy of the estimation of arterial oxygen saturation by pulse oximetry: a systematic review.

BACKGROUND: Pulse oximetry-derived oxygen saturation (SpO2) is an estimate of true arterial oxygen saturation (SaO2). The aim of this review was to evaluate available evidence determining the effect of skin tone on the ability of pulse oximeters to accurately estimate SaO2. METHODS: Published literature was screened to identify clinical and non-clinical studies enrolling adults and children when SpO2 was compared with a paired co-oximetry SaO2 value. We searched literature databases from their inception to March 20, 2023. Risk of bias (RoB) was assessed using the QUADAS-2 tool. Certainty of assessment was evaluated using the GRADE tool. RESULTS: Forty-four studies were selected reporting on at least 222 644 participants (6121 of whom were children) and 733 722 paired SpO2-SaO2 measurements. Methodologies included laboratory studies, prospective clinical, and retrospective clinical studies. A high RoB was detected in 64% of studies and there was considerable heterogeneity in study design, data analysis, and reporting metrics. Only 11 (25%) studies measured skin tone in 2353 (1.1%) participants; the remainder reported participant ethnicity: 68 930 (31.0%) participants were of non-White ethnicity or had non-light skin tones. The majority of studies reported overestimation of SaO2 by pulse oximetry in participants with darker skin tones or from ethnicities assumed to have darker skin tones. Several studies reported no inaccuracy related to skin tone. Meta-analysis of the data was not possible. CONCLUSIONS: Pulse oximetry can overestimate true SaO2 in people with darker skin tones. The clinical relevance of this bias remains unclear, but its magnitude is likely to be greater when SaO2 is lower. SYSTEMATIC REVIEW PROTOCOL: International Prospective Register of Systematic Reviews (PROSPERO): CRD42023390723.

Near-infrared spectroscopy data for foot skin oxygen saturation in healthy subjects.

Our objective was to evaluate normative data for near-infrared spectroscopy (NIRS) in 110 healthy volunteers by Fitzpatrick skin type (FST) and region of the foot. We obtained measurements of the dorsum and plantar foot using a commercially available device (SnapshotNIR, Kent Imaging, Calgary Canada). On the dorsum of the foot, people with FST6 had significantly lower oxygen saturation compared to FST1-5 (p < 0.001), lower oxyhaemoglobin compared to FST2-5 (p = 0.001), but there was no difference in deoxyhaemoglobin. No differences were found on the plantar foot. When comparing dorsal and plantar foot, there was higher oxyhaemoglobin (0.40 ± 0.09 vs. 0.51 ± 0.12, p < 0.001) and deoxyhaemoglobin (0.16 ± 0.05 vs. 0.21 ± 0.05, p < 0.001) on the plantar foot, but no differences in oxygen saturation (dorsal 70.7 ± 10.8, plantar 70.0 ± 9.5, p = 0.414). In 6.4% of feet, there were black areas, for which no NIRS measurements could be generated. All areas with no data were on the dorsal foot and only found in FST 5-6. People with FST6 had significantly larger areas with no data compared to FST 5 (22.2 cm2 ± 20.4 vs. 1.9 cm2 ± 0.90, p = 0.007). These findings should be considered when using NIRS technology. Skin pigmentation should be evaluated in future NIRS studies.

Integrating skin color assessments into clinical practice and research: A review of current approaches.

Skin color classification can have importance in skin health, pigmentary disorders, and oncologic condition assessments. It is also critical for evaluating disease course and response to a variety of therapeutic interventions and aids in accurate classification of participants in clinical research studies. A panel of dermatologists conducted a literature review to assess the strengths and limitations of existing classification scales, as well as to compare their preferences and utilities. We identified 17 skin classification systems utilized in dermatologic settings. These systems include a range of parameters such as UV light reactivity, race, ethnicity, and degree of pigmentation. The Fitzpatrick skin type classification is most widely used and validated. However it has numerous limitations including its conflation with race, ethnicity, and skin color. There is a lack of validation data available for the remaining scales. There are significant deficiencies in current skin classification instruments. Consensus-based initiatives to drive the development of validated and reliable tools are critically needed.

Correlation of fitzpatrick skin type and iris color with tumor size in 823 patients with uveal melanoma.

PURPOSE: To determine the correlation of Fitzpatrick Skin Type (FST) and iris color with tumor size (tumor thickness and basal diameter) in patients with uveal melanoma. DESIGN: Retrospective Cohort METHODS: Retrospective cohort from a single ocular oncology center of 823 patients with uveal melanoma and documented FST, iris color, and tumor size. Patients were classified by FST (type I, II, and III-V) and iris color (blue, green, and brown) on the basis of external facial photography. There were no FST type VI patients. Tumor thickness was classified into small [< 3 millimeter (mm)], medium (3.1-8.0 mm), or large (> 8.0 mm), and basal diameter into small (< 10 mm), medium (10.1-15 mm) or large (> 15 mm). The correlation of FST and iris color with tumor thickness and basal diameter was evaluated using the Kruskal-Wallis H test. RESULTS: The FST classification was type I (n = 92, 11%), type II (n = 643, 78%), or III-V (n = 88, 11%), and iris color was blue (n = 472, 57%), green (n = 102, 12%), or brown (n = 249, 30%). A comparison of FST revealed differences in mean tumor thickness (P = 0.04) and basal diameter (P = 0.006). Iris color showed no difference for mean tumor thickness (P = 0.41) or basal diameter (P = 0.48). There was a statistically significant difference with brown iris color relative to FST III-V for mean tumor thickness (P = 0.003) and basal diameter (P = 0.001) but no difference with blue or green iris color (P > 0.05). CONCLUSIONS: Iris color alone showed no difference in tumor size, but those with brown iris color and FST type III-V demonstrated larger tumor thickness and basal diameter.

Effect of skin color on optical properties and the implications for medical optical technologies: a review.

Significance: Skin color affects light penetration leading to differences in its absorption and scattering properties. COVID-19 highlighted the importance of understanding of the interaction of light with different skin types, e.g., pulse oximetry (PO) unreliably determined oxygen saturation levels in people from Black and ethnic minority backgrounds. Furthermore, with increased use of other medical wearables using light to provide disease information and photodynamic therapies to treat skin cancers, a thorough understanding of the effect skin color has on light is important for reducing healthcare disparities. Aim: The aim of this work is to perform a thorough review on the effect of skin color on optical properties and the implication of variation on optical medical technologies. Approach: Published in vivo optical coefficients associated with different skin colors were collated and their effects on optical penetration depth and transport mean free path (TMFP) assessed. Results: Variation among reported values is significant. We show that absorption coefficients for dark skin are ∼6% to 74% greater than for light skin in the 400 to 1000 nm spectrum. Beyond 600 nm, the TMFP for light skin is greater than for dark skin. Maximum transmission for all skin types was beyond 940 nm in this spectrum. There are significant losses of light with increasing skin depth; in this spectrum, depending upon Fitzpatrick skin type (FST), on average 14% to 18% of light is lost by a depth of 0.1 mm compared with 90% to 97% of the remaining light being lost by a depth of 1.93 mm. Conclusions: Current published data suggest that at wavelengths beyond 940 nm light transmission is greatest for all FSTs. Data beyond 1000 nm are minimal and further study is required. It is possible that the amount of light transmitted through skin for all skin colors will converge with increasing wavelength enabling optical medical technologies to become independent of skin color.

The Effect of Melasma on the Quality of Life in People with Darker Skin Types Living in Durban, South Africa.

Melasma is a common skin disorder of acquired hyperpigmentation that appears commonly on the face. Although asymptomatic, melasma causes psychosocial and emotional distress. This study aimed to assess melasma's severity on people with darker skin types, evaluate the effects of melasma on the quality of life (QoL), and establish QoL predictors in affected individuals. This was a cross-sectional analytic study that enrolled 150 patients from three private dermatology clinics in Durban, South Africa who were diagnosed with melasma. The severity of melasma alongside QoL were measured using a melasma area and severity index (MASI) score and melasma quality of life scale (MELASQoL), respectively. The associations among factors and QoL were explored using multivariable methods and stepwise regression analysis. p-values less than 0.05 were considered significant. Enrolled patients were predominantly females (95%), of which 76% were of black African ethnicity, 9% were of Indian ethnicity, and 15% had mixed ancestry, with an average age of 47.30 years. Family history revealed that 61% had no prior melasma cases, while 39% had affected relatives, most commonly mothers (41%). The cheeks were the most common site for melasma. MASI score of Masi (ß = 0.209, t = 2.628, p < 0.001), the involvement of cheeks (ß = -0.268, t = -3.405, p < 0.001), level of education (ß = -0.159, t = -2.029, p = 0.044), and being menopausal (ß = -0.161, t = -2.027, p = 0.045) were found to be predictors of QoL. A regression model was created to forecast MELASQoL using these four predictors. This equation's significance lies in its ability to enable the remote assessment of MELASQoL based on these four variables. It offers a valuable tool for researchers and medical professionals to quantitatively and objectively evaluate the impact of melasma on an individual's quality of life.

Demographic and clinical features of cutaneous malignant melanoma patients: A single center cohort study.

OBJECTIVE: There is a worldwide increase in the incidence of malignant melanoma (MM). Although it is a highly aggressive tumor and associated with high mortality and morbidity rates, it is highly curable if diagnosed early. Both genetic and environmental risk factors are associated with MM, which may show geographic variations. In this study we aimed to investigate the demographic and clinical features of cutaneous melanoma patients who are under follow-up in our department and whether there is an association between patients' characteristics and disease features. METHODS: Thirty-four patients with cutaneous MM who were under follow-up in the dermatology outpatient clinic, and dermoscopy unit at our hospital were retrospectively analyzed. The patients' demographic data and features related to MM were evaluated. RESULTS: Nineteen (55.9%) women and 15 (44.1%) men were enrolled in the study. When the patients were evaluated according to their Fitzpatrick skin types, type 2 was the most common in 21 (61.8%) of the patients, followed by type 3 in 9 (26.5%), and 1 in 4 (11.8%) patients. Twenty-two (64.7%) of the patients had a history of regular sun exposure. Twelve (35.3%) patients had a history of working outdoors. Sixteen of the patients (47.1%) had at least one sunburn history during childhood. The mean age at which patients were diagnosed with MM was 50.12±12.67 years. Age at diagnosis was found to be higher in those with actinic keratosis and those with solar lentigo (p=0.030, p=0.030; respectively). It was determined that there was a statistically significant difference in terms of localization according to the place of birth of the patients (p=0.007). CONCLUSION: We believe that defining the patients' characteristics and developing follow-up strategies accordingly, will improve the treatment rates in melanoma. Dermatologists should schedule personalized follow-up programs for patients who have priorly defined and regional risk factors.

Optimisation of skin phototype classification.

Understanding individuals' skin pigmentation and photosensitivity is important in judging risk of skin cancer and response to certain treatment modalities. However, individuals with darkly pigmented skin are poorly represented in the widely used Fitzpatrick skin phototype (FST) system. Moreover, the FST system is prone to misuse, as it relies on subjective patient and clinician assessment of skin type, and does not clearly differentiate pigmentation from photosensitivity. By evaluating the key literature surrounding the FST system, its criticisms and proposed alternatives, this review serves to understand how skin phototype classification can be optimised.