Introduction

Skin conditions in people with skin of color (SoC, defined as Fitzpatrick skin phototypes IV-VI, which refer to a wide range of darkly pigmented skin [1]) are underrepresented in dermatology training [2,3], despite the specialty’s reliance on visual clinical diagnosis [4]. Inadequate knowledge of how dermatological conditions manifest themselves in SoC can lead to delays in diagnosis and poor or even incorrect treatment, contributing to health inequities [3,5,6]. Studies of both students and dermatologists show that skin conditions in SoC are less likely to be correctly identified than those on lighter skin [7,8]. Some skin diseases occur differently in light skin and SoC, like Melasma [9] or Keloids which occur significantly more often in patients with SoC [10]. In contrast, melanoma is less common in patients with SoC; however, in patients with SoC the disease is often already at a more advanced stage at the time of diagnosis [11].

The lack of diverse representation of skin types in dermatology training undermines the ability of future doctors to diagnose and treat patients with SoC [12]. Students attribute their lack of confidence in diagnosing skin conditions in patients with SoC to inadequate curriculum coverage [13]. Further research is needed to determine the most effective strategies for improving education about skin type diversity in medical training and to explore how these methods can support the development of skills needed to provide culturally competent care [14]. In 2022, around 1.27 million people with an African migrant background lived in Germany, reflecting the country's highly diverse society [15]. As diverse societies are a global phenomenon and people with SoC need to be diagnosed and treated correctly everywhere, it is important that students and physicians worldwide learn how to diagnose skin diseases in patients with SoC.

To address this lacuna in dermatology education in Germany, we implemented a seminar on skin type diversity as part of the regular medical curriculum at the University Medical Center Hamburg-Eppendorf, Germany in 2023 [16]. Preliminary evaluations based on student self-assessments showed an increase in self-reported competence in managing skin diseases in SoC, resulting from the seminar. In addition, most students indicated that they would like to attend more SoC courses in the future [16]. However, whether the seminar effectively improves ability to correctly identify skin conditions in SoC has not been evaluated to date. Our initiative aligns with international efforts to enhance diversity in dermatology education. The American Academy of Dermatology (AAD), among others, has launched dedicated programs and educational resources aimed at increasing the visibility of SoC in educational material and clinical training [17].

This study aimed to assess the effectiveness of the SoC seminar at the University Medical Center Hamburg-Eppendorf in improving medical students’ ability to correctly identify skin conditions in people with SoC, as measured by objective tests.

Materials and methods

Results

General students’ characteristics

Out of a total of 172 students in the semester, 151 students attended the seminar (87.8%). The participation rate in the voluntary questionnaire survey was 94.0% (n = 142). Of the students, 57.7% were female (n = 82; representing the current gender distribution in medical studies at the University of Hamburg [20]) and the average age was 25.2 ± 2.6 years (range 21–35 years). 92.3% (n = 131) of the students were in their 7th semester. A high interest in dermatology was confirmed by 21.8% (n = 31) of the participants (Table 1).

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Table 1. General characteristics of the 142 students.

https://doi.org/10.1371/journal.pone.0342922.t001

Students‘ self-assessment

At the beginning of the seminar, 23.2% (n = 33) of the students stated they were familiar with skin type classification scales. There was a significant increase in self-reported knowledge of skin type scales at the end of the seminar (2.3 ± 1.1 vs. 4.0 ± 1.1, p < 0.001; Likert scale from 1 ‘very low knowledge’ to 6 ‘very high knowledge’; Fig 1A). The students’ self-assessment of their knowledge of the anatomical and physiological differences between light skin and SoC was 2.2 ± 1.1 on average (scale from 1 ‘very little knowledge’ to 6 ‘very high knowledge’). After attending the seminar, students rated their knowledge significantly higher than before (4.0 ± 1.0; p < 0.001; Fig 1B).

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Fig 1. Means and 95% confidence interval of the students’ self-assessment (n = 142); survey before and after the seminar.

A) Assessment of the knowledge of scales for classification of different skin types. B) Knowledge of the anatomical and physiological differences between light skin and SoC (C) Assessment of own ability to identify skin diseases in people with SoC.

https://doi.org/10.1371/journal.pone.0342922.g001

Identification of skin diseases in patients with SoC

At the beginning of the seminar, the percentage of accurately identified visual diagnoses was 54.8% (M = 4.4 correct diagnoses). The diagnoses with the lowest percentage of correct answers at the beginning of the seminar were melasma (26.8%) and keloids (40.1%). Vitiligo was correctly diagnosed by 87.3% of the students. Students with a high interest in dermatology showed a higher number of correctly identified visual diagnoses at the beginning of the seminar than students with a medium to low interest in dermatology (68.1% vs. 51.0%, p < 0.001). At the end of the seminar, there was a significant increase in the number of correct diagnoses which rose to an average of 92.5% (M = 7.4 correct diagnoses, t-test for paired samples: t(141)=−21.732, p < 0.001, Cohen’s d = 1.66). The greatest increases in correct diagnoses were shown for melasma (+65.5% correct answers), keloids (+51.4%) and tinea (+47.9%; Fig 2).

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Fig 2. Percentage of students that accurately identified each skin condition in skin of color pre-seminar and post-seminar (n = 142) as well as the p-values of the individual McNemar-tests.

https://doi.org/10.1371/journal.pone.0342922.g002

Self-assessed ability to diagnose skin diseases in SoC also increased significantly from 2.0 ± 0.9 (Likert scale from 1 ‘very low ability’ to 6 ‘very high ability’) at the beginning of the seminar to 3.6 ± 1.1 at the end of the seminar (p < 0.001; Fig 1C). No significant correlation was found between overall performance on the multiple-choice test and self-assessed diagnostic ability at the beginning (r = 0.10, p = 0.221). At the end of the seminar, performance on the multiple-choice test and self-assessed diagnostic ability showed a very weak positive correlation (r = 0.20, p = 0.020).

Discussion

Due to the lack of diverse representation of skin types in dermatology training, visual diagnosis of skin conditions in SoC is a challenge and a potential cause of misdiagnosis in clinical practice [7]. As the diversity of skin types in the patient population continues to increase, research into the effectiveness of newly developed modules/seminars is crucial to improving the medical curriculum. Our study demonstrated that the implementation of a specific SoC dermatology seminar increased the ability of medical students to correctly identify skin diseases in SoC on a both statistically and clinically significant level. For all eight dermatological conditions studied, there was an improvement in the students’ identification rates at the end of the seminar. Unlike our previous study [16], the improvement was not based on self-report alone but was objectified by a multiple-choice test. Our teaching methods included parts of perceptual learning. Perceptual learning is a change of perception as a result of experience. Interpreting visual findings is a core goal of dermatology education. Recognizing dermatologic conditions largely depends on implicit, non-analytical knowledge developed through exposure to images and patient cases [21,22].

The two diagnoses with the lowest proportion of correct answers in the pre-seminar test were melasma (26.8%) and keloids (40.1%), even though melasma is one of the most common hyperpigmentation skin disorders and occurs more commonly in SoC [9]. Keloids also occur significantly more often in patients with SoC [10]. Disparities in dermatologic health care disproportionately impact patients with SoC, leading to misdiagnoses and delayed treatment [23,24]. Among the various factors contributing to these disparities, one physician-dependent factor is the limited understanding of disease presentations in patients with SoC, which negatively affects the quality of care provided [25,26]. In our study, the number of correct diagnoses improved after the SoC seminar for both conditions, melasma (92.3%) and keloids (91.5%).

While melasma and keloids are bothersome but benign skin conditions, melanoma is a highly malignant tumor. While melanoma is less common in patients with SoC, those who are diagnosed often have more advanced disease [11]. This disparity is partly due to differences in the types of melanoma that predominantly affect patients with SoC, such as acral lentiginous melanoma. This type of melanoma is not associated with UV exposure and may be overlooked in clinical assessments that typically focus on UV-related risk factors [27]. In our study, the percentage of students who could correctly identify acral lentiginous melanoma at the end of the SoC seminar was 96.5%, whereas at the beginning of the seminar only 57.7% students rated this visual diagnosis correctly. To improve the ability of physicians to diagnose melanoma in SoC, dermatology education in medical schools needs to cover the differences in risk factors and a broader spectrum of clinical presentation of melanoma in different skin types [28].

Our findings demonstrate the great importance of incorporating SoC education into standard curricula to reduce health disparities. Furthermore, knowledge of skin type scales and of the anatomical and physiological differences between fair skin and SoC improved according to the students’ self-assessment. Although dermatology relies on visual diagnosis, a fundamental understanding of skin structure and function is crucial for managing skin diseases. For example, in patients with SoC, the risk of post-inflammatory hyperpigmentation is higher due to larger melanosomes and increased melanin content, while the likelihood of keloid formation is greater due to numerous, large, and multinucleated fibroblasts [29].

The skin diseases with the highest proportion of correct answers in the pre-seminar test were vitiligo (87.3%) and psoriasis (77.5%) – even before they were explained in detail during class. Vitiligo is a very characteristic skin condition and became known worldwide by the model Winnie Harlow and the singer Michael Jackson [30], which may explain the high number of correctly identified diagnosis in the pre-test. With a prevalence of around 2%, psoriasis is one of the most common chronic skin diseases in Germany, which may have contributed to the high identification rates [31]. Although both conditions were often correctly diagnosed in the pre-test, an improvement in the ability to correctly identify vitiligo and psoriasis was observed after the seminar.

Previous research has investigated the implementation of dermatology courses focusing on SoC for medical students, but with less participants than in our study and in voluntary classes. Arza et al. [13] conducted a voluntary virtual seminar for medical students with 70 attendees, focusing on skin health equity and education on skin diseases prevalent in SoC. After the seminar, most students reported lack of confidence about their ability to diagnose skin conditions in SoC and most rated institutional learning resources for skin diversity education as inadequate [13].

Shango et al. [32] offered a voluntary supplemental module with 77 attendees as part of a second-year dermatology curriculum, which comprised thirteen cases of common skin conditions in African American patients. After completing the module, the medical students reported a significant increase in confidence in diagnosing skin conditions in SoC, too [32].

Han et al. [8] developed a virtual lecture for medical students covering skin diseases of all skin types. The study of 43 participants showed an improvement of 30.1% in correct visual diagnosis among 9 skin conditions in patients with SoC. The most significant improvements were seen in psoriasis vulgaris (54.9%), rosacea (47.3%) and seborrheic keratosis (40.6%). In addition, the authors showed that on the pre-examination questionnaire, students scored lower for diagnosing skin diseases in patients with SoC than for patients with a lighter skin.

However, unlike the SoC seminar we developed, participation in the courses of Han et al. [8], Shango et al. [32] and Arza et al. [13] was voluntary and therefore not integrated into the regular curriculum. In our study cohort, only 21.8% of students reported a high interest in dermatology, whereas the participants in the three studies mentioned before were probably very interested in dermatology to attend a voluntary class. As our seminar was compulsory, even students with a moderate or low interest in the field attended the SoC seminar. Therefore, our results demonstrate that targeted seminars can improve medical student’s ability to correctly identify skin conditions in SoC regardless of students’ personal interest in the subject. Given that the treatment of dermatological conditions such as atopic dermatitis and skin cancer screening is not limited to dermatologists [33,34], a thorough understanding of skin diseases in different skin types is highly relevant for all future physicians. Comparable studies have shown the positive effects of SoC programs also for dermatology residents [35] and physician assistants [36].

A strength of our study is the robust assessment of diagnostic skills using a multiple-choice test at the beginning and the end of the seminar. As the seminar was integrated into the regular, mandatory curriculum, all students attended regardless of their interest in dermatology, resulting in a large study cohort. The study is limited by its quasi-experimental pre-post design without a control group, which does not allow causal conclusions to be drawn. Additionally, the results could have been influenced by potential confounding factors such as students’ prior dermatological experience, baseline knowledge and varying levels of interest in dermatology. The multiple-choice test was administered immediately after the seminar. This immediate post-seminar assessment provides valuable insight into short-term learning effects but does not allow conclusions about sustained knowledge retention or diagnostic performance over time. Future research should include follow-up assessments after several months to evaluate the durability of learning outcomes and the long-term impact of SoC education on students’ diagnostic ability. Multiple-choice questions listing diseases do not accurately reflect real-life scenarios. To improve the validity of assessments, future studies should use standardized real-life cases. The study was conducted in just one single university hospital in Germany, which limits the generalizability of the findings to other geographical areas. The transferability of the results may be affected by cultural and institutional variables. Differences in medical education curricula and in the representation of diverse populations across countries could influence how similar teaching formats are perceived and how effective they are in improving students’ ability to correctly identify skin diseases. Further research in diverse educational and cultural settings is needed to examine the broader applicability of such interventions.

Conclusion

This study highlights the importance of incorporating SoC training into medical curricula to reduce health disparities by equipping future physicians in providing equitable care. We strongly recommend further research to determine best practices for the sustainable integration of SoC dermatology within medical school education, including studies with long-term follow up.

Supporting information

Acknowledgments

We acknowledge financial support from the Open Access Publication Fund of UKE - Universitätsklinikum Hamburg-Eppendorf.