What Causes Growth Under or On the Nail Bed? A Guide to Nail Health Concerns

Unusual growths under or on the nail can be both concerning and uncomfortable. Whether you’ve noticed a small bump under your fingernail or a strange change in the nail bed, it’s important to understand what might be happening. While many nail growths are harmless, some may point to underlying health issues that need professional attention. This article explores common causes, symptoms to watch for, and when to consult a healthcare provider.

What Is a Growth Under the Nail?

A growth under the nail refers to any abnormal tissue, bump, or mass that develops beneath the nail plate or on the nail bed—the skin beneath the nail. These growths can affect the shape, color, and integrity of the nail and sometimes cause pain or pressure.

Common Causes of Nail Bed Growths

1. Subungual Exostosis (Bone Spur)

This is a benign bony growth that typically forms under the toenail or fingernail. It may cause the nail to lift or feel painful when pressure is applied. Often triggered by trauma or repetitive stress, it requires evaluation by a specialist.

2. Subungual Wart

Caused by the human papillomavirus (HPV), these warts can develop beneath the nail and often distort the nail plate. They may be painful and are usually treated with topical medications, cryotherapy, or minor surgery.

3. Glomus Tumor

A rare but painful vascular tumor that typically appears under the fingernail. It may cause sensitivity to cold, throbbing pain, and a visible blue or reddish spot under the nail.

4. Mucous Cyst

These fluid-filled sacs usually develop near the cuticle and can sometimes extend under the nail bed, causing grooving or deformity of the nail. They are commonly associated with osteoarthritis.

5. Fungal Infections

Fungal infections (onychomycosis) can lead to thickened, crumbly, or discolored nails, sometimes with buildup underneath. Though not a “growth” in the tumor sense, the overgrowth of fungal organisms can cause structural changes.

6. Melanoma

A dark streak or raised area under the nail could indicate a rare form of skin cancer known as subungual melanoma. It typically appears as a dark brown or black stripe and may spread with time. Any pigmented or irregular growth under the nail should be evaluated immediately.

Symptoms to Watch For

• Persistent pain or pressure under the nail

• Discoloration (black, brown, red, or blue patches)

• Thickening or lifting of the nail plate

• Sensitivity to touch or cold

• Bleeding under the nail without injury

• Changes in nail shape or growth pattern

Diagnosis and When to See a Doctor

If you notice any unusual growth under your fingernail or on the nail bed that doesn’t go away, worsens, or causes discomfort, it’s time to consult a dermatologist or podiatrist. Diagnosis may involve:

• Physical examination

• Dermoscopy

• X-rays (to identify bone involvement)

• Biopsy (for suspicious growths)

• Fungal culture

Prompt diagnosis is essential, especially to rule out malignancies or infections that can spread if untreated.

Treatment Options

Treatment depends on the cause of the growth. Common approaches include:

• Topical or oral antifungals for infections

• Surgical removal of benign tumors like exostosis or glomus tumors

• Cryotherapy or laser therapy for warts

• Excision and follow-up for cysts

• Oncological referral for suspicious or confirmed cancerous growths

Maintaining Nail Health

To help prevent issues:

• Keep nails trimmed and clean

• Avoid biting or picking at nails and cuticles

• Wear protective gloves during chores

• Treat nail injuries promptly

• Avoid prolonged exposure to damp environments

Final Thoughts

A growth under or on the nail bed can range from minor to serious. While some cases are simple to treat, others require medical intervention to avoid complications. Paying attention to nail changes and seeking early care can make all the difference in maintaining nail and overall health.

If you notice a persistent or unusual growth beneath your fingernail, don’t wait. Consult a healthcare professional to ensure you get the right diagnosis and treatment.