Dark Spots Under Fingernails Could Indicate Serious Skin Cancer

A dark discoloration under your fingernail might seem harmless at first, but it can sometimes be a sign of a rare and potentially serious form of skin cancer called subungual melanoma. This type of melanoma develops under the nails and is not caused by sun exposure, distinguishing it from other skin cancers. It typically appears as a dark line or spot, which many people might dismiss as a minor pigmentation change or a vitamin deficiency.

Recognizing the signs early is crucial because if detected in the initial stages when it affects only the upper skin layer, treatment can be less invasive, and prognosis improves. However, due to its rarity, subungual melanoma often goes unnoticed or is misdiagnosed, leading to delayed treatment.

One notable case involves Lauren Koltcz, who initially thought her brown nail mark was a vitamin deficiency but later discovered it was melanoma. She underwent surgical removal of the affected nail and surrounding tissue, highlighting the importance of prompt medical attention.

Subungual melanoma belongs to a group called acral lentiginous melanoma, which tends to develop on areas like palms and soles, usually in non-sun-exposed parts of the body. It can occur across all races and ages, making awareness vital for everyone. While it is less common than other skin cancers, it can be more aggressive.

Dermatologists recommend comprehensive skin checks, including examination of the nails, to identify suspicious lesions early. Advanced imaging tools like the Vectra 3D can assist in detecting and monitoring skin abnormalities with high precision, although such scans are often not covered by insurance and can be costly.

If you notice a dark streak, spot, or discoloration under your nail that persists or changes over time, consult a healthcare professional promptly. Early detection and treatment are essential in managing this rare but serious condition.

Source: https://medicalxpress.com/news/2025-05-rare-scary-dark-fingernail-cancer.html