What is a hard bump at the base of toenail?

There are several potential causes for a hard bump at the base of a toenail. Here are some possibilities:

1. Subungual Exostosis: It is a benign bony growth that develops under the toenail. It typically appears as a hard bump or ridge near the base of the nail and is usually painless.

2. Onychocryptosis (Ingrown Toenail): An ingrown toenail occurs when the edges or corners of the nail grow into the surrounding skin, leading to pain and inflammation. It can cause a hard bump or swelling at the base of the affected nail.

3. Infection (Paronychia): A bacterial or fungal infection of the nail fold or surrounding skin can lead to swelling, redness, and the formation of a hard, pus-filled bump at the base of the toenail.

4. Nail Matrix Tumor: Though rare, tumors of the nail matrix, which is responsible for nail growth, can cause hard bumps or nodules to develop at the base of the toenail.

5. Trauma: Injuries to the nail or nail bed caused by stubbing or dropping something heavy on the foot can sometimes result in a hard bump or bruise under the nail.

If you notice a hard bump at the base of your toenail and it is causing discomfort or affecting your daily activities, it's best to consult a healthcare professional, preferably a podiatrist or dermatologist. They can properly examine the bump, determine its cause, and recommend the most appropriate treatment.