Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(3):e2024209 1 Nail Changes and Periungual Dermatitis in a Finger of a Seven-Year-Old Girl Maria Francesca Baracca1,2, Luca Rapparini1,2, Michela Starace1,2, Iria Neri1, Bianca Maria Piraccini1,2 1 Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy 2 Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy Citation: Baracca MF, Rapparini L, Starace M, Neri I, Piraccini BM. Nail Changes and Periungual Dermatitis in a Finger of a Seven-Year- Old Girl. Dermatol Pract Concept. 2024;14(3):e2024209. DOI: https://doi.org/10.5826/dpc.1403a209 Accepted: April 28, 2024; Published: July 2024 Copyright: © Baracca 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. Piraccini BM and Neri I contributed equally to this work and share senior authorship. Corresponding Author: Luca Rapparini, MD, Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, Via Massarenti 1, 40138 Bologna, Italy. Phone: +39 051 214 4843, E-mail: luca.rapparini2@studio.unibo.it Case Presentation A 7-year-old girl was referred for a 1-year history of der- matitis restricted to the distal pulp of the left fourth finger. She denied sucking the finger and had no history of atopic dermatitis. Previous patch tests had ruled out allergic contact dermatitis to the most important contact allergens. The clin- ical examination revealed eczematous changes restricted to the tip of the fourth finger, characterized by mild erythema, scales, and fissures. The nail plate was raised due to mild subungual hyperkeratosis and onycholysis. A diagnosis of parakeratosis pustulosa was suspected, and the treatment with potent topical corticosteroids led to clinical improve- ment, with almost complete resolution of skin signs observed within one month. No recurrences were seen at the 6-month follow-up visit. Teaching Point Parakeratosis pustulosa is a typical and exclusive pediatric condition, more commonly seen in girls aged 5 to 7 years. It frequently affects a single finger, typically the thumb or index finger, and manifests with mild eczematous changes of the pulp along with psoriasiform nail changes [1]. It is con- sidered a possible clinical presentation of eczema or psoriasis [1]. The condition usually begins with pustules or vesicles, followed by eczematous changes, and may progress to pul- pitis, though rarely. Nail alterations develop after the skin inflammatory changes and include mild subungual hyper- keratosis and onycholysis, often more pronounced on one side of the nail. Differential diagnosis includes onychomy- cosis, nail sucking, chronic paronychia, and eczema. Patch test helps to exclude allergic contact dermatitis. The course 2 Image Letter | Dermatol Pract Concept. 2024;14(3):e2024209 of parakeratosis pustulosa is chronic with spontaneous re- mission over time. In some patients it can evolve into nail psoriasis, typically mild [2]. References 1. Tosti A, Peluso AM, Zucchelli V. Clinical features and long- term follow-up of 20 cases of parakeratosis pustulosa. Pediatr Dermatol. 1998;15(4):259–63. doi: 10.1046/j.1525- 1470.1998.1998015259.x. PMID: 9720686. 2. Richert B, André J. Nail disorders in children: diagnosis and management. Am J Clin Dermatol. 2011 Apr 1;12(2):101-12. doi: 10.2165/11537110-000000000-00000. PMID: 21348541. Figure 1. (A, B) Eczematous changes of the distal pulp of the left fourth finger, (B, C) associated with subungual hyperkeratosis and (C, D) onycholysis.