The untold burden of isolated nail psoriasis: Delayed diagnosis and significant risk of psoriatic arthritis in a retrospective study at an academic center.

To the Editor: Up to 80% of psoriasis patients experience onychodystrophy during their lifetimes, and those with nail involvement have significant quality of life impact.1Stewart C.R. Algu L. Kamran R. et al.The impact of nail psoriasis and treatment on quality of life: a systematic review.Skin Appendage Disord. 2021; 7: 83-89Crossref PubMed Scopus (12) Google Scholar A small subset of psoriasis patients (5%-10%) have nail changes with no or limited (<5%) cutaneous findings.2Rigopoulos D. Baran R. Chiheb S. et al.Recommendations for the definition, evaluation, and treatment of nail psoriasis in adult patients with no or mild skin psoriasis: a dermatology and nail expert group consensus.J Am Acad Dermatol. 2019; 81: 228-240Abstract Full Text Full Text PDF PubMed Scopus (68) Google Scholar Our objectives were to characterize clinical and histological characteristics and prevalence of psoriatic arthritis (PsA) in patients with isolated nail psoriasis (NP). Following Weill Cornell Medicine Institutional Review Board approval, all isolated NP cases (January 1, 2001-December 21, 2022) were queried from EPIC.3Miller R.C. Lipner S.R. No association of metabolic syndrome with isolated nail psoriasis in a retrospective single-centre academic center.J Eur Acad Dermatol Venereol. 2022; (Epub ahead of print. https://doi.org/10.1111/jdv.18611)Crossref Scopus (1) Google Scholar Demographic, clinical, and histopathologic data were collected. Patient average and highest nail psoriasis severity index scores were calculated using clinical photographs. χ2 and 2-tailed t tests were used for categorical and continuous variables, respectively (P < .05). Eighty-seven patients had isolated NP, with 45 (51%) females and mean age 46 years (Table I). Average time to presentation was 2.9 years, with mean 8 nails involved. Ten (11%) had PsA, with some concordance between nails and joints affected, and for 8/10 arthritis was present concurrently or preceded nail changes (Supplementary Table I, available via Mendeley at https://doi.org/10.17632/8s244wjp3x.2). Patients with vs without PsA had higher nail psoriasis severity index scores (7 vs 6, P = .024) and were older (23% [≥45] vs 3% [<45], P = .011) (Table II).Table IDemographic, clinical, and histopathologic characteristics of all patients with isolated nail psoriasisN = 87 (%)∗The patients in our study partially overlapped with participants studied by Rhiannon et al.2Demographics Age [avg. (range)]46 (13-88) GenderFemale45 (51)Male42 (49) SmokerNo76 (87)Yes11 (13) Psoriatic arthritis10 (11) Family history psoriasis2 (2)Clinical characteristics LocationHand50 (58)Feet2 (2)Both35 (40) Number of nails [avg. (range)]8 (1-20) Only 1 nail affected9 (10) Clinical featuresOnycholysis69 (79)Nail pitting61 (70)Splinter hemorrhage24 (28)Nail thickening24 (28)Salmon patch23 (26)Subungual hyperkeratosis20 (23)Yellowing14 (16)Ridges12 (14)Crumbling6 (7) Common clinical dyadsOnycholysis + pitting57 (66)Onycholysis + thickening29 (33)Onycholysis + splinter hemorrhage28 (32)Onycholysis + salmon patch27 (31) Common clinical triadsOnycholysis + pitting + thickening13 (15)Onycholysis + pitting + salmon patch12 (14)Onycholysis + pitting + splinter hemorrhage11 (13)Onycholysis + splinter hemorrhage + thickening9 (10) Histologic featuresParakeratosis69 (79)Neutrophils42 (48)Incomplete keratinization28 (32)Subungual hyperkeratosis22 (25) Time to presentation (mo) [avg (range)]35 (0.375-360)∗ The patients in our study partially overlapped with participants studied by Rhiannon et al.2Rigopoulos D. Baran R. Chiheb S. et al.Recommendations for the definition, evaluation, and treatment of nail psoriasis in adult patients with no or mild skin psoriasis: a dermatology and nail expert group consensus.J Am Acad Dermatol. 2019; 81: 228-240Abstract Full Text Full Text PDF PubMed Scopus (68) Google Scholar Open table in a new tab Table IIAssociation of demographic and clinical characteristics of isolated nail psoriasis with psoriatic arthritisPsA (%)P valueSex Female5 (13)1 Male5 (13)Age <451 (3).011 ≥459 (23)Smoking status Smoker1 (9).67 Non-smoker9 (14)Location Hands4 (9).20 Feet1 (50) Both5 (16)Disease location Nail bed4 (19).64 Nail matrix5 (9) Nail bed + nail matrix1 (11)Skin psoriasis Yes4 (17).35 No6 (10)Clinical dyads Onycholysis + pitting4 (10).34 Onycholysis + thickening4 (20).29 Onycholysis + splinter hemorrhages3 (16).70 Onycholysis + salmon patch5 (25).070Clinical triads Onycholysis + pitting + thickening2 (15).79 Onycholysis + pitting + salmon patch2 (17).70 Onycholysis + pitting + splinter hemorrhage1 (10).75 Onycholysis + splinter hemorrhage + thickening2 (22).73Max NAPSI score (average)7.024No. of nails involved (average)11.13Time to presentation (mo) (average)64.23The bold values indicates the significant P values.NAPSI, Nail psoriasis severity index. Open table in a new tab The bold values indicates the significant P values. NAPSI, Nail psoriasis severity index. The most common single clinical features were onycholysis (79%) and nail plate pitting (70%), which together was the most common clinical dyad. The most common histologic features were parakeratosis (79%) and neutrophil infiltration (48%). To our knowledge, this is the largest study documenting clinical and histologic features in patients with isolated NP.4Balestri R. Rech G. Rossi E. et al.Natural history of isolated nail psoriasis and its role as a risk factor for the development of psoriatic arthritis: a single-center cross-sectional study.Br J Dermatol. 2017; 176: 1394-1397Crossref PubMed Scopus (9) Google Scholar We show that diagnosis was delayed by almost 3 years, approximately 1/10 had PsA, and that arthritis was most often diagnosed concurrently with NP. Higher PsA risk was associated with age ≥45 years and higher nail psoriasis severity index scores. Therefore, we delineate the substantial physical burden experienced by patients with isolated NP and taken together with known quality of life impairment,1Stewart C.R. Algu L. Kamran R. et al.The impact of nail psoriasis and treatment on quality of life: a systematic review.Skin Appendage Disord. 2021; 7: 83-89Crossref PubMed Scopus (12) Google Scholar our study should serve as an impetus for dermatologists to improve their diagnostic accuracy. Similarly, in a cross-sectional study of 36 patients with isolated NP, 7 (19%) developed PsA.4Balestri R. Rech G. Rossi E. et al.Natural history of isolated nail psoriasis and its role as a risk factor for the development of psoriatic arthritis: a single-center cross-sectional study.Br J Dermatol. 2017; 176: 1394-1397Crossref PubMed Scopus (9) Google Scholar In a retrospective study of 4146 psoriasis patients, onychodystrophy was the strongest predictor of concomitant PsA (odds ratio = 2.93; 95% CI, 2.51-3.42; P < .001).5Langenbruch A. Radtke M.A. Krensel M. et al.Nail involvement as a predictor of concomitant psoriatic arthritis in patients with psoriasis.Br J Dermatol. 2014; 171: 1123-1128Crossref PubMed Scopus (100) Google Scholar Histologically and with high-resolution magnetic resonance imaging, the extensor tendon crossing the distal interphalangeal joint apposes the nail unit, explaining the high frequency of nail pathology in patients with PsA.5Langenbruch A. Radtke M.A. Krensel M. et al.Nail involvement as a predictor of concomitant psoriatic arthritis in patients with psoriasis.Br J Dermatol. 2014; 171: 1123-1128Crossref PubMed Scopus (100) Google Scholar Based on our finding that 11% of patients with isolated NP had PsA, and the close proximity between the nail apparatus and joint, we hypothesize a reciprocal relationship, with nail unit inflammation precipitating PsA. While our study is limited by small sample size and retrospective single-center design, our nail division serves as a major nail referral center. Information on duration of disease, and PsA timing was not available for all patients. Patients with isolated NP experience substantial disease burden with delayed diagnosis and significant PsA risk. Since PsA risk was associated with more severe nail disease, clinical recognition of NP is paramount, with nail plate clippings performed for corroboration. Dermatologists can play key roles in early diagnosis of isolated NP, improving quality of life and possibly preventing progression to PsA. Dr Lipner is a consultant for Ortho-Dermatologics, Hoth therapeutics, and BelleTorus Corporation. Chang, Lee, and Desai have no conflicts of interest to declare.