Dermatology: Practical and Conceptual Letter to the Editor | Dermatol Pract Concept. 2025;15(2):4872 1 Bilateral Foot Skin Nodules in Children: Talar Callosities in 7 Patients and Differential Diagnosis Mario Cutrone1, Ramon Grimalt2, Dirk Van Gysel3,4, Julia Nowowiejska5, Vincenzo Piccolo6 1 Ambulatorio di Dermatologia Pediatrica, Centro di Medicina Mestre, Venice, Italy 2 Universitat Internacional de Catalunya, Barcelona, Spain 3 Department of Pediatrics, O.L.Vrouw Hospital Aalst, Aalst, Belgium 4 Interdisciplinary Unit of Pediatric Dermatology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium 5 Department of Dermatology and Venereology, Medical University of Bialystok, Poland 6 Dermatology Unit, University of Campania, Naples, Italy Key words: Talar callosities, Pediatric Dermatology, Foot Diseases Citation: Cutrone M, Grimalt R, Van Gysel D, Nowowiejska J, Piccolo V. Bilateral Foot Skin Nodules in Children: Talar Callosities in 7 Patients and Differential Diagnosis. Dermatol Pract Concept. 2025;15(2):4872. DOI: https://doi.org/10.5826/dpc.1502a4872 Accepted: September 11, 2024; Published: April 2025 Copyright: ©2025 Cutrone 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: Assist. Prof. Julia Nowowiejska, MD, PhD, Medical University of Bialystok, Poland, Zurawia 14 St, 15-540 Bialystok. ORCID ID: 0000-0002-6870-1167. E-mail: julia.nowowiejska@umb.edu.pl Introduction Over the past 10 years, we have documented seven cases of talar callosities, all in males aged 6 to 14 years (Figure 1 A-G, Table 1). Of these, four were accompanied by other dermato- logic conditions (atopic dermatitis, carotenemia, and psoriasis), while in the remaining three cases, it was an isolated condition. Case Presentation and Discussion None of the patients had ligamentous hyperlaxity, and only in one case (case 6, associated with autism spectrum dis- order) was it associated with a habit of spending time in a cross-legged position. In only two cases (case 6, where the lesions were particularly thickened and scaling, and case 7, where psoriasis overlapped) did we find it useful to prescribe topical steroids (mometasone furoate), which led to rapid improvement (but not the disappearance of the talar callosi- ties). Talar callosity is a condition of the foot skin that is little known and probably underdiagnosed. Clinically, it presents as a callosity/thickening typically 2.0 to 2.5 cm in diameter that can vary in its location, from the anterolateral aspect to the dorsum of the feet, usually away from common shoe point of contact [1,2]. It can be associated with smaller callosities over the ipsilateral lateral malleolus, fifth metatarsal base or head, or other bony prominence in the foot. The color is usu- ally that of normal skin. Usually bilateral, it tends to be more prominent on one foot [1]. Talar callosity was also known in the past as “callosity of crossed-legged sitting” or “prayer foot” because it was always considered in relation to praying (similar to Davener’s dermatosis of the back), meditation, and other activities that involve sitting crossed-legged such 2 Letter to the Editor | Dermatol Pract Concept. 2025;15(2):4872 as yoga or eating [1,3]. In children, talar callosity has been described in relation to crossed-legged or kneeling positions to play on the floor [1]. In a series of 26 cases, association with generalized ligament laxity was also reported [2]. The diagnosis is clinical, and the histologic findings are ortho- keratosis, hypergranulosis, and dermal papillary fibrosis [1]. The differential diagnosis includes granuloma annulare (mainly in the deep subcutaneous variant, firmer and harder, Figure 1H, 1I), psoriasis (with the typical scales and salmon color), nummular eczema (very itchy and usually present at the same time in other sites, Figure 1L), tinea corporis (which has the typical raised welt), warts (more typically present in plantar region and with typical dermatoscopy, Figure 1J), keloid scar (Figure 1K), and frictional dermatitits artefacta, due to repetitive manipulation of the skin secondary to psy- chological distress. In our series of cases, the bilaterality al- ready described by the few papers published previously was confirmed, while neither the association with ligamentous laxity (absent in all seven cases) nor that with the cross- legged position (present and perhaps actually involving only case 6, suffering from autism and accustomed to sitting in that position for prolonged periods) confirmed. It is reason- able, therefore, that the true cause of talar callosity should be reconsidered and perhaps identified in particular atti- tudes or foot support patterns of the child during walking and standing. One additional pathogenetic hypothesis may be related to the aforementioned differential diagnosis with frictional dermatitis artefacta, where a compulsive habit of skin rubbing by the patient might play a role in the genesis of the disorder. In any case, talar callosity remains an asymp- tomatic condition that does not require therapy. However, it is important to be aware of this condition in order to avoid mistakes in the differential diagnosis with other conditions that do require therapy [1]. Conclusions For the definitive clarification of the underlying cause of ta- lar callosity, more case series will be needed to allow a better understanding of this phenomenon. Figure 1. Clinical manifestation of talar callosities and differential diagnoses. A–G: talar callosities; H: deep granuloma annulare; I: superficial granuloma annulare; J: wart; K: keloid; L: eczema. Table 1. The Summary of our Cases of Talar Callosities. Age and Sex Laterality Number of lesions Color Pain/ Itching Crossed Legs Position Other Diseases 1 10-year-old male Bilateral 3 Normal skin No No No 2 8-year-old male Bilateral 3 Minimal scaling No No Atopic eczema 3 9-year-old male Bilateral 3 Normal skin No No No 4 11-year-old male Bilateral 3 Minimal erythema No No No 5 7-year-old male Bilateral 3 Yellowish No No Carotenemia 6 14-year-old male Bilateral 3 Erythema with scaling No Yes Autism Spectrum Disorder 7 6-year-old male Bilateral 3 Erythema with scaling No No Psoriasis Letter to the Editor | Dermatol Pract Concept. 2025;15(2):4872 3 2. Lim KB, Tawng DK, Lokino ES, Raveendran R, Tay GT. Talar cal- losity in children–what, who, why? J Pediatr. 2011;158(2):340. DOI: 10.1016/j.jpeds.2010.08.035. 3. Saif I, Woywodt A. Talar callosity (‘prayer foot’) in a haemodi- alysis patient. NDT Plus. 2009;2:89-90. DOI: 10.1093/ndtplus /sfn181. References 1. Luna-Bastante L, López Negrete E, Alonso Naranjo L, Roustan G, Alfageme F. Sonography of a case series of talar cal- losities. J Ultrasound. 2022;25:983-7. DOI:10.1007/s40477-021- 00566-y.