Dermatology: Practical and Conceptual Original Article | Dermatol Pract Concept. 2024;14(4):e2024235 1 Celebrating Diversity: Unveiling the Characteristics of Nail Psoriasis and Nail Lichen Planus in 30 Patients With Skin of Color Stephano Cedirian1,2, Michela Starace1,2, Alessio Natale1,2, Federico Quadrelli1,2, Kaya L. Curtis3, Shari Lipner4, Bianca Maria Piraccini1,2 1 Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Policlinico S. Orsola-Malpighi, Bologna, Italy 2 Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, Italy 3 Weill Cornell Medical College, New York, USA 4 Department of Dermatology, Weill Cornell Medicine, New York, USA Key words: Nail psoriasis, Nail lichen planus, Skin of color Citation: Cedirian S, Starace M, Natale A, et al. Celebrating Diversity: Unveiling the Characteristics of Nail Psoriasis and Nail Lichen Planus in 30 Patients With Skin Of Color. Dermatol Pract Concept. 2024;14(4):e2024235. DOI: https://doi.org/10.5826/dpc.1404a235 Accepted: June 17, 2024; Published: October 2024 Copyright: ©2024 Cedirian et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing Interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding Author: Alessio Natale, MD, Via G. Massarenti, 1 - 40138 - Bologna, Italy. Tel: +39 0512144849. E-mail: alessio.natale@studio.unibo.it Introduction: Dermatological conditions affecting the nails can manifest differently in individuals with distinct skin tones. This often leads to difficulty in the recognition of nail diseases, especially in people with skin of color (SoC), who are not well represented in the literature. Objectives: Our aim was to provide dermatologists with useful clues for prompt recognition and diagnosis of nail psoriasis (NPso) and nail lichen planus (NLP) in people with SoC. Methods: We described the ungual manifestations of NPso and NLP in a population of 30 patients with SoC. Diagnosis was primarily based on clinical examination; in cases of diagnostic uncertainty, a biopsy of the nail matrix was performed to obtain histological conclusive evidence. Results: Of the 30 people with SoC in the analysis, 24 patients had NPso with a median Fitzpatrick phototype of 4.77, and six patients had NLP with a median Fitzpatrick phototype of 5. Regarding the 24 patients with NPso, 10 presented with trachyonychia, nine displayed nail pitting, eight showed onycholysis, and 12 had subungual hyperkeratosis, while splinter hemorrhages were visible in two patients, and activation melanonychia was discernible on the nail plates of eight patients. Of the ABSTRACT 2 Original Article | Dermatol Pract Concept. 2024;14(4):e2024235 Introduction In recent years, there has been a growing recognition of the importance of understanding how dermatological conditions affect individuals with skin of color (SoC). The spectrum of skin tones within this population is marked by variations in melanin content, which plays a pivotal role in determining the color and reactivity of the skin and its appendages, such as hair and nails [1,2]. Among the wide range of nail disorders, nail psori- asis (NPso) and nail lichen planus (NLP) are relatively lesser-known conditions when it comes to people with SoC. Regarding NPso in the general population, nail involvement is highly prevalent in psoriasis, with reported rates varying between 47.4% and 78.3% in different studies. Nail bed and nail matrix psoriasis can manifest in various ways, including the presence of pitting, onycholysis, subungual hyperkerato- sis, and changes in the color of the nail plate. Severe NPso, which can lead to functional impairment, exerts a substan- tial impact on the quality of life of those affected. This un- derscores the crucial importance of timely diagnosis and intervention [3,4]. On the other hand, NLP is a relatively rare condition, with a global prevalence estimated at 0.5% to 1.0%. Approx- imately 10% to 15% of patients with lichen planus have nail manifestations. NLP primarily affects fingernails, with some involvement in toenails. It is more common in adults, with only a small percentage of cases occurring in children [5]. The clinical features of NLP can vary, but common symp- toms include longitudinal ridging, nail plate thinning, lamina fragmentation, red or mottled lunula, and pterygium. Nail bed involvement can lead to onycholysis, subungual hyper- keratosis, and splinter hemorrhages. Dorsal pterygium, a V-shaped scarring of the proximal nailfold, is a specific sign of NLP but represents late-stage disease. Diagnosis is chal- lenging due to the lack of specificity in symptoms, which can lead to delays in diagnosis and ultimately result in functional impairment [6]. Both conditions have been significantly underrepre- sented in the field of dermatology, as our understand- ing is primarily based on small case reports found in the literature [7–9]. Objectives Our case series analysis aimed to shed light on the presenta- tion and characteristics of NPso and NLP in 30 patients with SoC. This study emphasizes the significance of recognizing the distinct clinical patterns and manifestations of these con- ditions in this specific patient population. Methods In this case series, we identified a total of 30 patients with SoC who had been diagnosed with NPso or NLP. We col- lected clinical data, including demographic information, clinical presentation, and nail-specific characteristics such as nail pitting, oil-drop patches, longitudinal melanonychia, and other nail plate abnormalities. Diagnosis of NPso and NLP was primarily based on clinical examination. In cases of diagnostic uncertainty, we performed a 3 mm punch biopsy of the nail matrix to obtain conclusive evidence. Results Our study encompassed a cohort of 24 patients diagnosed with NPso (M = 21; F = 5). The median age within this group was 37.25 years, with a corresponding median Fitzpatrick phototype of 4.77. Among these patients, our observations revealed that four exhibited post-inflammatory pigmentation at the proximal nailfold, 10 presented with trachyonychia, nine displayed nail pitting, and three manifested onychor- rhexis. Regarding nail bed manifestations, onycholysis was noted in eight patients, subungual hyperkeratosis was identi- fied in 12 patients, and splinter hemorrhages were visible in two patients. Furthermore, activation melanonychia was vi- sually discernible on the nail plates of eight patients. Results are fully displayed in (Table 1). In a separate cohort of six male patients diagnosed with NLP, the median age was 38.8 years. Their me- dian Fitzpatrick phototype was 5.0. In all six cases, post- inflammatory pigmentation was observed at the proximal nail. Regarding the nail matrix signs, three patients exhibited trachyonychia, while the other three displayed longitudinal fissures. Five patients showed subungual hyperkeratosis, six patients diagnosed with NLP, all had post-inflammatory pigmentation on the proximal nail, with three patients exhibiting trachyonychia and three others having longitudinal fissures; subungual hy- perkeratosis was found in five patients, while three patients displayed activated melanonychia. Conclusion: People with SoC exhibit a peculiar clinical presentation of both NPso and NLP, and a better understanding is essential to providing timely and effective care. Original Article | Dermatol Pract Concept. 2024;14(4):e2024235 3 Table 1. Data Gathered on Patients with Skin of Color Affected by Nail Psoriasis. Patient N° Age Fitzpatrick Phototype Sex Pnf Nail Matrix Sign Nail Bed Signs Nail Plate Signs Digit Hands Digit Feet 1 45 VI M / Longitudinal fissures Subungual hyperkeratosis / III L / 2 34 V M Post- inflammatory pigmentation Pitting Subungual hyperkeratosis Activation melanonychya ALL R I, II, V R + I, V L 3 29 IV M / Trachyonychia Subungual hyperkeratosis ALL / 4 39 V M Post- inflammatory pigmentation Pitting Subungual hyperkeratosis Activation melanonychya I, II, IV, V R / 5 43 IV M / Trachyonychia / Activation melanonychya ALL ALL 6 24 IV M / / Onycholysis / ALL I R, I L 7 35 V M / Trachyonychia Onycholysis / III R / 8 27 V M / Longitudinal fissures / / III L I, II R + I L 9 29 IV M / Pitting + Trachyonychia Subungual hyperkeratosis / ALL / 10 29 V M / Pitting Subungual hyperkeratosis Activation melanonychya I, II, V L I R, I, III L 11 33 V M / / Onycholysis ALL ALL 12 40 IV M / Longitudinal fissures / Activation melanonychya I L / 13 55 IV M / Trachyonychia Subungual hyperkeratosis / I, II R / 14 41 VI M Post- inflammatory pigmentation Pitting + Trachyonychia Subungual hyperkeratosis / I, II R I, II, III R + I, II, III L 15 29 V M / Pitting + Trachyonychia / / ALL / 16 32 IV M / Trachyonychia Subungual hyperkeratosis Activation melanonychya I, II, IV R ALL 17 43 VI M / Trachyonychia / / ALL ALL 18 49 VI / Post- inflammatory pigmentation Trachyonychia Onycholysis / I, II, III L / 19 33 V / / / Subungual hyperkeratosis + onycholysis / IV R / 20 77 IV / / Pitting Onycholysis + splinter hemorrhages Activation melanonychya ALL L / 21 10 V / / Pitting Subungual hyperkeratosis Activation melanonychya / I L 22 48 V / / / Onycholysis / ALL L / 23 32 V / / / Onycholysis + splinter hemorrhages / II, IV L / 24 38 IV / / Pitting Onycholysis / IV, V L I R + I L Abbreviations: PFN: pterygium; L: left; R: right. 4 Original Article | Dermatol Pract Concept. 2024;14(4):e2024235 and three patients presented with activation melanonychia as a distinctive nail plate sign. Results are fully displayed in Table 2. Discussion NPso may display unique characteristics in individuals with skin of color. Nail pitting is a common sign, ranging from small pits to large irregular furrows on the nail plate. In our case series, nine patients had nail pitting. Oil-drop patches, a specific diagnostic sign, may not always be visible in this population, as shown in our results. Extended disease activ- ity can lead to nail plate crumbling and thickening, often re- sulting from total nail matrix destruction, which corresponds to ten of our cases who developed trachyonychia (Figures 1 and 2). Differential diagnosis is essential to exclude fungal in- fections, especially when NPso presents without evident skin involvement. Chang and colleagues conducted a retrospec- tive examination of NPso cases at Weill Cornell Medicine [8]. They discovered that among the 87 NPso patients included in their analysis, 82% fell into skin types I–III, while 18% were classified as skin types IV–VI. The patients with skin types IV–VI experienced a longer period before receiving a diagnosis (59 months compared to 24 months) and exhib- ited higher average NAPSI scores, indicating greater disease severity when compared to individuals with skin types I–III. The study’s authors emphasized the presence of disparities in NPso diagnosis, particularly concerning patients with SoC, who tended to be diagnosed almost three years later and pre- sented with more severe cases of the condition. This delay in Table 2. Data Gathered on Patients with Skin of Color Affected by Nail Lichen Planus. Patient N° Age Fitzpatrick Phototype Sex Pnf Nail Matrix Sign Nail Bed Signs Nail Plate Signs Digit Hands Digit Feet 1 33 IV M Post- inflammatory pigmentation Longitudinal fissures Subungual hyperkeratosis Activation melanonychya I, III L + I, II, III, IV R / 2 44 VI M Post- inflammatory pigmentation Trachyonychia Subungual hyperkeratosis Activation melanonychya ALL I, II R + I, II L 3 45 V M Post- inflammatory pigmentation Trachyonychia Subungual hyperkeratosis / I, II L + I, II R / 4 34 V M Post- inflammatory pigmentation Trachyonychia Subungual hyperkeratosis Activation melanonychya ALL / 5 47 IV M / Longitudinal fissures Subungual hyperkeratosis / I L + I, II, III R / 6 30 VI M Post- inflammatory pigmentation Longitudinal fissures Onycholysis / ALL I, II R + I, II L Abbreviations: PFN: pterygium; L: left; R: right. Figure 1. Global photography of a patient affected by nail psoriasis (Fitzpatrick phototype V) with subungual hyperkeratosis, longitudi- nal melanonychia and overall nail dystrophy. Figure 2. Onychoscopy image of nail alterations due to nail psoria- sis: it reveals subungual hyperkeratosis, longitudinal melanonychia, and irregular pitting. Original Article | Dermatol Pract Concept. 2024;14(4):e2024235 5 Figure 3. Global photography of a patient affected by nail lichen planus (Fitzpatrick phototype VI) with visible trachyonychia and longitudinal fissures. Figure 4. Onychoscopy image of trachyonychia due to nail lichen planus: nail crumbling and longitudinal fissures are visible. diagnosis among SoC patients might be attributed to factors such as limited access to health care and the challenges asso- ciated with identifying NPso on darker skin, which can ob- scure clinical signs [8]. Case series like ours play a crucial role in expanding our collective understanding of this subject and working towards reducing dermatological disparities across different ethnicities. As for NLP, it may present differently in individuals with SoC. Kluger presented a case of NLP affecting a young man [9]; his patient displayed a darkened area on the upper part of the nailfold, along with nail ridges, swelling, and scar- ring, indicating that the nail matrix was affected. There was also excessive subungual hyperkeratosis, onycholysis, and a “pup tent” appearance. In our cases, three patients showed longitudinal activation melanonychia, and five displayed periungual pigmentation. Notably, post-inflammatory hy- perpigmentation of the proximal nailfold and longitudinal activation melanonychia are more common in individuals with darker skin tones due to melanocytic activation. In- deed, concerning melanonychia, in individuals with dark skin, the nail matrix contains a relatively higher density of melanocytes compared to those with lighter skin. The num- ber of melanocytes in the nail matrix can range from 208 to 576 cells/mm². This high melanocyte density contributes to the pigmentation of the nail plate. Furthermore, melanocytes are most prominent in the distal matrix, particularly in the active component of the distal matrix, while the proximal matrix contains melanocytes that are largely dormant. This distribution pattern contributes to the formation of longi- tudinal melanonychia in individuals with dark skin [10]. Regarding nail matrix involvement in NLP, it can result in various nail plate abnormalities, not different from those seen in people with lighter skin tones, including longitudinal ridging, nail plate thinning, longitudinal fissuring, trachyony- chia, and erythema of the lunula, as partially seen in our cases (Figures 3 and 4). Additionally, it is known that nail bed involvement may lead to onycholysis and subungual hy- perkeratosis; five of our patients showed subungual hyper- keratosis, mirroring the clinical features of NLP in lighter Fitzpatrick phototypes [6]. Finally, we emphasize that patients affected by NPso typ- ically presented with more severe manifestations compared to those with NLP. This discrepancy may stem from the greater challenge in diagnosing NPso compared to NLP as well as to delayed dermatological consultations among the former group. Limitations There are some limitations to our study, such as the rela- tively small sample size, the retrospective nature of the study conducted at two medical institutions, and the subjective na- ture of skin type and nail lesions assessment. To confirm the validity of our findings, it is essential to conduct a broader multicenter study involving a larger number of patients with diverse skin tones. Conclusion Our case series highlights the unique manifestations of NPso and NLP in patients with SoC. Recognizing these distinct clinical presentations, including post- inflammatory hyperpigmentation and absence of oil spots for instances, is crucial to providing timely and effective care. While variations exist, the diagnostic and treatment approaches remain largely consistent across different skin tones, emphasizing the importance of tailored care for each patient. References 1. Lester JC, Taylor SC, Chren MM. Under-representation of skin of colour in dermatology images: not just an educational issue. Br J Dermatol. 2019;180(6):1521-1522. DOI:10.1111/bjd.17608. 6 Original Article | Dermatol Pract Concept. 2024;14(4):e2024235 7. Ankad BS, Gupta A, Alekhya R, Saipriya M. Dermoscopy of Onycholysis Due to Nail Psoriasis, Onychomycosis and Trauma: A Cross Sectional Study in Skin of Color. Indian Dermatol Online J. 2020;11(5):777-783. DOI:10.4103/idoj .IDOJ_475_19. 8. 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