Black Streak on Nail: Is it Cancer? Viral Post Sparks Fear, Doctors Explain Reality

• A Reddit user's faint brown nail stripe, present for years, was diagnosed as subungual melanoma after users advised a doctor's visit.
• Melanonychia, a black or brown line on the nail, can be caused by injury, nutrient deficiency, or medication, and is common in people with darker skin tones.
• While often benign, a single nail showing such marks could indicate subungual melanoma, a serious skin cancer under the nail.
• Subungual melanoma is a severe skin cancer under the nail, appearing as dark streaks; early detection is crucial for successful treatment.
• Symptoms include a black/brown line on one nail, changes in nail shape/color, swelling, irritation, bumps, or bleeding, necessitating medical consultation.

Why It Matters: While nail streaks are often harmless, a persistent or new mark on a single nail warrants immediate medical evaluation for cancer.