Melanoma and fungus look similar beneath a toenail, although melanoma looks more like a bruise, and fungus has more of a yellow and green color to it. Distinguishing between the two is important, as undiagnosed melanoma can become fatal if it metastasizes, according to Salt Lake Podiatry Center.
The technical term for skin cancer beneath the nail is subungual melanoma, and it can develop on the feet or the hands. It strikes people with darker skin pigment more frequently, and the first sign is a black or brown discolored spot that resembles a bruise beneath the nail. People who develop this bruising without having hit their nails on anything should seek medical attention and a biopsy if the physician finds it necessary, explains Salt Lake Podiatry Center.
Fungal infections beneath the toenail become more common as people age and the immune system develops deficiencies. The most effective treatment begins with antifungal pills, such as Lamisil, which has a success rate between 50 and 60 percent if taken every day for three months. Topical medicines like Penlac go on the nail daily for up to a year. However, topical medicines have not shown more than a 40 percent effectiveness, notes Salt Lake Podiatry Center.