# Bony lump under the toenail > A subungual exostosis is a non-cancerous bony lump that grows from the tip of a toe bone under the nail. It can cause pain and a lifted or misshapen nail, and it's easily mistaken for a wart or ingrown nail. Surgery to remove it is the usual treatment once an X-ray confirms it. Guide in [Skin and nails](https://footanklelowerlimb.com.au/learn/topics/skin-and-nails), from Foot Ankle Lower Limb: https://footanklelowerlimb.com.au/learn/subungual-exostosis Reviewed by Andrew Schox, BSc(Hons) PGradDipPod MPod (Podiatrist) on 11 November 2026. Next review by 11 November 2027. - **It's a non-cancerous bony lump** that grows from the tip of a toe bone under the nail, usually on the big toe. - **It's often found in children and young adults** and can cause pain, redness and a lifted or misshapen nail. - **It's easily mistaken for a wart or ingrown toenail,** and an X-ray is the key test. - **Surgery is the usual treatment once it's confirmed,** though not every lump needs it. - **Nail changes after surgery are the most common complication,** and the lump can sometimes return. ## What is a bony lump under the toenail, and how common is it? The clinical name is subungual exostosis (also called Dupuytren's exostosis). It's a benign (non-cancerous) growth of bone from the tip of the end bone of a toe, or less often a finger [1]. It grows under the nail and can cause pain and a misshapen nail [1]. It's described as uncommon or rare [1][2]. Most lumps are on the big toe [3]. It's diagnosed most often in children and young adults [4]. ## What causes it, and who gets it? The cause isn't known for certain. Most clinicians think it's a reaction to repeated minor injury or ongoing irritation [1][5]. An infection, an inherited tendency and a cartilage cyst have also been suggested [1]. An earlier injury to the toe is the best-recorded link, but it's reported in only about 30% of cases [6]. So there's no reason to assume you caused it. Children, teenagers and young adults are the people most often affected [4]. ## What does it feel like, how is it diagnosed, and what else could it be? It usually starts as a firm lump under the end of the nail that doesn't move, with thick, hard skin on top. It grows slowly over weeks to months and can lift the nail off its bed [7]. Typical symptoms are pain, redness, swelling, a misshapen nail and shoes rubbing on it [3][1]. As it grows, the toe can swell, the skin can break down into a sore (an ulcer) and the nail bed can become infected [4]. An X-ray is the key test to confirm it [4]. Looking at a tissue sample under the microscope can help tell it apart from other lumps [8]. It's often mistaken for a wart, an ingrown nail, an infection of the skin beside the nail (paronychia) or a fungal nail [9][8]. Missed or late diagnosis is common, and it can lead to lasting pain and nail changes [1][9]. A lump that doesn't respond to wart treatment is a reason to look further [8][10]. > [!tip] Try this > Look at the nail on a painful toe. Is there a firm lump under or at the tip of the nail, or is the nail being lifted? Note when you first noticed it and whether it has changed. Some features can mark a nail lump as more serious: - **A lump that doesn't improve with treatment, looks unusual or ulcerates** can need imaging and a tissue sample (biopsy) to rule out cancers such as melanoma or squamous cell carcinoma [10][5]. - **A dark area under a nail that wasn't caused by an injury** can be a sign of melanoma [11]. - **Signs of infection** are a high temperature, hot, red, swollen and painful skin around the nail, and pus. A toe that hasn't improved after 3 weeks of treatment, or is getting worse, is also a warning sign [12]. - **Diabetes or poor circulation** make any nail problem more serious, because diabetes can affect healing [7][13]. ## What helps first? Once an X-ray confirms it, the usual treatment is surgery to remove the lump together with the cartilage cap that covers it [4]. Not every lump needs surgery. These lumps rarely go away on their own and can grow, so the decision depends on how much the lump affects your comfort and quality of life [14]. Padding or changing your shoes isn't a reliable way to deal with it, especially if the lump is getting worse or causing a sore or infection [14]. ## What helps if that isn't enough? A lump is more likely to come back if it wasn't completely removed. Being younger, especially under 18, is also linked with it returning, possibly because bones are growing quickly and the edge between normal bone and the lump is hard to see [15]. In children and teenagers, missing the diagnosis or treating it inappropriately can cause harm, through overtreatment or recurrence [16]. A lump that regrows or looks different from the original can need more imaging or a biopsy [10]. ## What's the outlook, and can it come back? After removal the outlook is generally good. Changes to the nail are the most common complication, while recurrence and infection are less common [1]. The nail can be permanently lost or misshapen [14]. It may also regrow thickened, and the skin can be slow to heal [17]. Because the cause isn't known, there's no known way to prevent a subungual exostosis. Complete removal is what lowers the chance of it returning [15]. Comfortable, well-fitting shoes are sensible general advice. After surgery, regrowth of the lump, increasing pain or the signs of infection described above are the things to watch for. ## Common questions ### Is a bony lump under the toenail cancer? No. A subungual exostosis is a benign growth of bone, which means it's not cancer. Several other nail lumps can look similar, though, and some of them are cancers. That's why a lump that looks unusual or doesn't respond to treatment can need imaging and a tissue sample to rule other causes out. ### Can it go away on its own? It rarely does. These lumps can stay the same or slowly grow over time. Not every lump needs surgery, though. The decision usually depends on how much the lump affects your comfort, your walking and the shoes you can wear. ### Can children get a bony lump under the toenail? Yes. It's diagnosed most often in children, teenagers and young adults, usually on the big toe. It can also affect other toes, and less often a finger. In young people it's important that the lump is recognised and treated appropriately. ### Do tight shoes cause it? Nobody knows exactly what causes it. Repeated minor injury or irritation is the leading idea, and shoes rubbing on the lump is a common symptom. But most people with it have no recorded injury. Comfortable, well-fitting shoes are sensible, but they aren't known to prevent it. ## Further reading - [Bony lump under the toenail on Clindice](https://clindice.com/subungual-exostosis) - [Exostosis: Types, Symptoms & Treatment](https://my.clevelandclinic.org/health/diseases/25114-exostosis), Cleveland Clinic - [2 TOPIC](https://www.wyevalley.nhs.uk/media/102608/2_SUBUNGUAL_EXOSTOSIS.pdf), NHS - [Ingrown toenail: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/001237.htm), MedlinePlus - [Management of nail problems](https://www.chelwest.nhs.uk/your-visit/patient-leaflets/surgery-services/management-of-nail-problems), NHS - [iMSK - podiatric surgery - North Tees and Hartlepool NHS Foundation Trust](https://www.nth.nhs.uk/services/podiatric-surgery/), NHS ## Sources 1. Subungual exostosis of the toes: a systematic review · DaCambra MP, Gupta SK, Ferri-de-Barros F · Clinical Orthopaedics and Related Research · 2014. https://doi.org/10.1007/s11999-013-3345-4 2. Subungual Exostosis Systematic Review and Meta-Analysis · Pérez-Palma L, Manzanares-Céspedes MC, Giralt de Veciana E · Journal of the American Podiatric Medical Association · 2018. https://doi.org/10.7547/17-102 3. The Influence of Clinical Factors on Treatment Outcome and a Recurrence of Surgically Removed Protruded Subungual Osteochondroma and Subungual Exostosis · Dąbrowski M, Rusek D, Dańczak-Pazdrowska A et al. · Journal of Clinical Medicine · 2023. https://doi.org/10.3390/jcm12196413 4. Surgical treatment of nail bed subungual exostosis · Malkoc M, Korkmaz O, Keskinbora M et al. · Singapore Medical Journal · 2016. https://doi.org/10.11622/smedj.2015180 5. Clinical diagnosis and treatment of subungual exostosis in children · Li H, Li H, Qi X et al. · Frontiers in Pediatrics · 2022. https://doi.org/10.3389/fped.2022.1075089 6. Bizarre Parosteal Osteochondromatous Proliferation Revisited · Nishio J, Shinohara Y, Nakayama S et al. · In Vivo (Athens, Greece) · 2025. https://doi.org/10.21873/invivo.13981 7. Nail disorders · NHS. https://www.rightdecisions.scot.nhs.uk/borders-ref-help-toolkit/podiatry/nail-disorders/ 8. A Case of Subungual Exostosis Mimicking Verruca Vulgaris · Gruzmark FS, Zimmerman L, Joyce J · Cureus · 2024. https://doi.org/10.7759/cureus.76564 9. Subungual Exostosis Presenting as a Pyogenic Granuloma-like Lesion with Reactive Myofibroblastic Proliferation in Two Young Women · Fox R, Katsarma E, Tiffin N et al. · Dermatopathology (Basel, Switzerland) · 2022. https://doi.org/10.3390/dermatopathology9020024 10. Malignant Melanoma Misdiagnosis in the Diabetic Foot. What Can We Learn From the Published Literature? · Bristow IR, Reynolds ML, Young M · Journal of Foot and Ankle Research · 2026. https://doi.org/10.1002/jfa2.70162 11. Symptoms of melanoma skin cancer · NHS · 2017. https://www.nhs.uk/conditions/melanoma-skin-cancer/symptoms/ 12. Ingrown Toenail · NHS. https://www.wmic.wales.nhs.uk/wp-content/uploads/2026/07/FINAL-PIL-Ingrowing-Toenail-v2-July-26-Eng.pdf 13. Ingrowing toenail · NHS. https://www.wsh.nhs.uk/CMS-Documents/Patient-leaflets/TraumaandOrthopaedics/5424-3-Ingrowing-Toenail.pdf 14. Bony spurs (exosectomy) · Mallard A · Royal Orthopaedic Hospital. https://roh.nhs.uk/services-information/foot-and-ankle/bony-spurs-exosectomy 15. A Case of Subungual Exostosis With Early Postoperative Recurrence and Rapid Growth · Murata S, Tsuchie H, Nagasawa H et al. · Cureus · 2024. https://doi.org/10.7759/cureus.73933 16. Subungual (Dupuytren's) exostosis · Multhopp-Stephens H, Walling AK · Journal of Pediatric Orthopedics · 1995. https://doi.org/10.1097/01241398-199509000-00006 17. Subungual exostosis surgery · Kent Community Health NHS Foundation Trust · 2024. https://www.kentcht.nhs.uk/leaflet/subungual-exostosis-surgery/ --- This is general information, not advice about your own situation. To discuss your issues, book with one of our podiatrists. In an emergency, call 000.