A woman posted on Reddit about a light brown vertical line on her thumbnail that wouldn’t go away. While it looked harmless, users urged her to see a doctor, warning it could signal serious conditions, including melanoma.
Some commenters shared their own experiences—ranging from harmless melanonychia to cancer diagnoses—emphasizing the importance of medical checks. The woman later updated that her GP had referred her to a dermatologist.
Although such lines can be benign, doctors stress they should never be ignored, as they may indicate underlying health issues or, in rare cases, skin cancer.
