A bump under a nail can be concerning. It can stem from minor injuries or more complex medical conditions. While some causes are harmless and resolve naturally, others may require professional attention. Understanding these reasons helps determine if medical evaluation is needed.
Common Causes of Bumps Under Nails
Trauma and injury often cause bumps under the nail. A direct impact, like hitting a finger or dropping an object, can lead to a subungual hematoma. This is bleeding beneath the nail plate, causing pain, throbbing, and black, blue, or purple discoloration. Repetitive pressure from ill-fitting shoes or activities can also cause similar blood collections.
Benign growths like myxoid cysts can form near or under the nail. Also known as digital mucous cysts, these are small, shiny, skin-colored, or translucent lumps often found near finger or toe joints. While usually painless, if a myxoid cyst grows under the nail or involves its root, it can cause a groove down the nail’s length or even lead to nail splitting. Warts (verruca vulgaris) can also grow in the nail area, creating a raised or bumpy texture.
Medical Conditions That Can Cause Bumps Under Nails
Several medical conditions can manifest as a bump under the nail. Tumors, both non-cancerous and cancerous, are possibilities. Non-cancerous glomus tumors are rare, small (usually less than 7mm), reddish-blue lesions often found under the nail bed. They cause severe pain, sensitivity to cold temperatures, and tenderness to touch, sometimes leading to irregular nail growth.
Another benign growth is subungual exostosis, a bony outgrowth typically occurring under the big toenail. This can cause pain when pressure is applied and may distort or lift the nail. Fibromas, including periungual and subungual types, are non-cancerous fibrous growths that can develop under or around the nail, leading to discomfort, pain, or changes in nail appearance.
In rare instances, a bump under the nail can indicate a more serious condition, such as subungual melanoma, a type of skin cancer. This often appears as a dark brown or black streak that runs vertically along the nail, which may widen or change over time and is not necessarily linked to a prior injury. Unlike a bruise, a melanoma streak typically does not grow out with the nail. Squamous cell carcinoma is another rare but serious cancerous growth that can affect the nail unit.
Fungal infections are a common medical cause for nail changes that can resemble a bump. These infections cause the nail to thicken, become discolored (white, yellow, brown, or black), brittle, and sometimes separate from the nail bed, creating a raised appearance. Psoriasis, an inflammatory skin condition, can also affect nails, leading to symptoms like pitting, discoloration, and subungual hyperkeratosis, where excess keratin builds up under the nail, creating a thickened area that feels like a bump.
When to Seek Professional Medical Advice
Consulting a healthcare professional is advisable if a bump under the nail exhibits certain characteristics. Persistent or worsening bumps, especially those that do not resolve within a few weeks, warrant medical evaluation. Significant pain or discomfort, particularly if severe, ongoing, or interfering with daily activities, also warrants advice.
Changes in nail appearance are also warning signs. This includes new or changing discoloration, especially dark brown or black streaks not caused by trauma, or any changes in the nail’s shape or its separation from the nail bed. Signs of infection, such as increasing redness, swelling, warmth, or pus around the nail, require prompt medical attention. Individuals with underlying health conditions, such as diabetes, should be cautious and seek medical advice for any nail changes, as they may be at higher risk for complications like infections and impaired healing.