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Vol. 100. Issue 6.
Pages 472-474 (1 June 2024)
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Vol. 100. Issue 6.
Pages 472-474 (1 June 2024)
Scientific Letter
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Subungual exostosis in childhood. Considerations on a series of 32 patients
Exostosis subungueal del pie en la infancia. Consideraciones sobre una serie de 32 pacientes
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Javier Miguel Bielsaa,
Corresponding author
jdemiguelbielsa@gmail.com

Corresponding author.
, Luis Lerena Pérez-Aradrosa, Victoria Eugenia Gómez Palacioa, Isabel Parada Avendañoa, Jorge Gil Albarovaa,b
a Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Miguel Servet, Zaragoza, Spain
b Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain
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Table 1. Main characteristics of the patients.
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Dear Editor:

Subungual exostosis is a benign bone tumour that develops in children and young adults. The slow growth of the spongy bone of the distal phalanx of the toe protrudes under the nail bed resulting in nail dystrophy. Clinically, it presents as a subungual hyperkeratotic tumour, which may or may not be painful, with inflammation or superinfection around the affected area. It develops in the toes, usually in sites subject to repeated trauma, such as the distal phalanx of the hallux or great toe.1

The differential diagnosis comprehends a range of conditions associated with onychodystrophy, such as onychomycosis, plantar warts or ingrown toenails. The mere suspicion of a tumour as the cause of ungual abnormalities can streamline the diagnosis and treatment. The diagnosis is made by plain radiography with two orthogonal projections, which allows visualization of the bony overgrowth (Fig. 1).

Figure 1.

Gross appearance and two radiographic projections of a typical case of subungual exostosis.

(0.26MB).

The treatment usually consists of the surgical excision of the exostosis from the distal phalanx under local anaesthesia combined with onychoplasty of the nail matrix. The patient was allowed to walk immediately after surgery and active rest was prescribed during recovery. The possible postoperative complications include wound infection or discomfort calling for the use of wider footwear until the sutures are removed.

We present our experience with this condition with the aim of offering paediatricians an action plan, including the recognition of the typical presentation, the required diagnostic tests and appropriate treatment and referral. To this end, we analysed a retrospective cohort of patients manage din our hospital between 2000 and 2022 through the review of health records, collecting data on the location of the tumour, time elapsed to diagnosis, number of specialists consulted, previous misdiagnoses and the histological findings in the surgical specimen. We also analysed the scores obtained one in an anonymous patient satisfaction and postoperative functioning survey (using the American Orthopaedic Foot And Ankle Society score) conducted by telephone, during which the patient (or the parents in the case of underage patients) provided verbal consent to participation in the study.

We entered the anonymised data for the 32 included patients in a table (Table 1). There was a predominance of male patients, lesions involving the right foot and lesions involving the first toe, with a mean age at the time of surgery of 9.88 years. The mean time elapsed to referral to the trauma department and the definitive diagnosis was 13.02 months.

Table 1.

Main characteristics of the patients.

Case  Year of diagnosis  Sex  Age (years)  Lesion location  Delay to diagnosis (months)  Number of specialists  Initial diagnosis  Procedure  Complications  Recurrence  AOFAS score 
2022  Right V DP  Undetermined nail lesion  EX  No  –  – 
2022  Right I DP  Hyperkeratosis  EX  No  –  – 
2022  14  Right I DP  24  Ingrown toenail  EX  SW infection  –  100 
2022  13  Left I DP  Nail dystrophy  EX  No  No  100 
2020  Right I DP  12  Abscess  EX  No  Yes (at 1 year)  100 
2020  10  Right I DP  12  Common warts  EX  No  No  100 
2018  10  Right V DP  Nail dystrophy  EX  SW infection  No  100 
2018  10  Left I DP  12  Papilloma  EX  No  No  100 
2018  10  Right IV DP  12  Onychopapilloma  EX  No  No  100 
10  2018  Left I DP  108  Exostosis  EX  No  No  100 
11  2017  10  Right V DP  12  Subungual bone spur (heterotopic ossification)  EX  No  No  100 
12  2017  14  Right V DP  36  Common warts  EX  No  No  100 
13  2017  Left I DP  12  Bone bruise with unfavourable outcome  EX  Yes (nail dystrophy)  No  100 
14  2016  Left III DP  Exostosis  EX  No  No  100 
15  2016  Right I DP  12  Exostosis  EX  No  No  98 
16  2014  Left I DP  Common warts  EX    No  93 
17  2014  13  Right I DP  Bone bruise with unfavourable outcome  EX  No  No  91 
18  2014  Left II DP  Exostosis  EX  No  No  98 
19  2014  10  Right III DP  Abnormal mass  EX  No  No  100 
20  2014  11  Right I DP  Abscess/Cyst  EX  No  No  100 
21  2014  12  Right I DP  Ingrown toenail  EX  Yes (ingrown nail)  No  – 
22  2013  Left I DP  ND  –  No data  EX  –  –  100 
23  2013  Right I DP  Abscess  EX  No  No  NR 
24  2013  Left V DP  12  Subungual bone spur (heterotopic ossification)  EX  No  Yes (at 1 year)  100 
25  2011  Left I DP  Onychopapilloma  EX  No  No  93 
26  2010  10  Left I DP  24  Onychopapilloma  EX  No  Yes (at 1 year)  88 
27  2010  12  Left II DP  18  Onychopapilloma  EX  Yes (3 months)  No  100 
28  2008  10  Right I DP  Exostosis (in follow-up for a different diagnosis)  EX  No  No  NR 
29  2007  Right I DP  12  Verruga plantar  EX  No  Yes (2 years)  100 
30  2006  14  Right I DP  Initial diagnosis  EX  No  Yes (2 years)  100 
31  2006  Right II DP  12  Number of specialists  Undetermined nail lesion  EX  No  No  100 
32  2005  11  Left I DP  Hyperkeratosis  EX  No  No  100 

DP, distal phalanx (involved toe expressed in roman numerals); EX, excision-onychoplasty; SW, surgical wound.

Missing data noted with the symbol –.

The telephonic survey included a total of 27 participants, corresponding to 84.37% of the patients identified in the review. The mean score in the clinical rating scale was 98.55 (over 100), reflecting a good outcome in a majority of patients. None of the patients reported pain. Five reported deformities in nail growth during the follow-up that did not have an impact on postoperative functioning or patient satisfaction. All surgical specimens were diagnosed as osteochondroma resulting from bizarre parosteal osteochondromatous proliferation.2

Osteochondroma accounts for 33.4% of benign skeletal tumours and 10.1% of all bone tumours. When the tumour arises from the distal phalanx, it is more likely to affect the toes3 and present with subungual involvement, typically in children or adolescents, with a 2:1 male-to-female ratio. They most frequently involve the great toe, followed by the fifth toe, and are usually isolated lesions.4 It has been hypothesised that they are congenital tumours of very small size at birth5 whose presence becomes apparent as they develop during childhood. Subungual exostoses chiefly have a distal location and their cortical bone is continuous with the distal phalanx.6 Although the diagnosis and treatment were correct, the time elapsed from the initial related visit at the primary care level to the initial visit to the traumatologist was long, with a mean delay of more than 1 year.

Subungual exostosis is a condition that needs to be taken into account in paediatric primary care practice. Due to the nail changes that it entails, its morphological characteristics or the mere unawareness of the disease, the diagnosis may be delayed, involving several specialists, if it is not correctly suspected at the outset. If there is awareness and suspicion, a mere plain radiograph of the lesion with two orthogonal projections suffices to confirm the diagnosis. Once it is diagnosed, referral to a trauma specialist facilitates early treatment, which can achieve satisfactory clinical and cosmetic outcomes. Since these tumours are benign, the follow-up is relatively short (until approximately 1 month after the patient has resumed normal activity, scheduling of subsequent check-ups as needed), with early resolution of the clinical manifestations.

Funding

This research did not receive any external funding.

Conflicts of interest

The authors have no conflicts of interest to declare.

Acknowledgments

We thank the Section on Paediatric Trauma of the Hospital Universitario Miguel Servet and their valuable work in collaboration with the Department of Paediatrics of the Hospital Materno Infantil de Zaragoza.

References
[1]
F. Yousefian, B. Davis, J.C. Browning.
Pediatric subungual exostosis.
[2]
P. Rana, A. Duhan, S. Verma, R. Siwach.
Bizarre parosteal osteochondromatous proliferation of phalanx.
Indian J Pathol Microbiol [Internet], 56 (2013), pp. 71-72
[3]
M. Tritto, G. Mirkin, X. Hao.
Subungual exostosis on the right hallux.
J Am Podiatr Med Assoc [Internet], 111 (2021),
[4]
S. Chiheb, Y. Slimani, R. Karam, F. Marnissi, F. Hali.
Subungual exostosis: a case series of 48 patients.
Skin Appendage Disord [Internet], 7 (2021), pp. 475-479
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J.W. Ricardo, I. Chikeka, H. Umans, S.R. Lipner.
Subungual osteochondroma in a pediatric patient.
[6]
K.L. Sang, S.J. Moon, H.L. Young, S.G. Hyun, K.K. Jae, H.B. Goo.
Two distinctive subungual pathologies: Subungual exostosis and subungual osteochondroma.
Foot Ankle Int., 28 (2007), pp. 595-601
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