There are many different disorders that can affect the appearance of the nails, including infectious causes such as fungus, yeast, or bacteria; conditions that affect the appearance of the nail plate such as psoriasis; underlying systemic diseases, injury, or age-related changes; and growths arising in or near the nails such as benign tumors, warts, cysts, moles, and even certain skin cancers.
Infectious causes of nail disorders can be treated with medications for fungus, yeast, or bacteria.* Psoriasis or lichen planus, which are inflammatory diseases of the skin and nails, may be more difficult to treat. However, there have been recent advances in treating these conditions. A type of cyst called a myxoid cyst or tumor can appear near the nail fold (below the cuticle) and cause the nail to form a vertical ridge. If the cyst is treated (often by incision and drainage followed by injection of a steroid solution), the ridge will often resolve.* Other benign tumors may be surgically treated.* Warts growing under the nail may be treated with liquid nitrogen or injections or applications of certain chemical compounds.*
It is important to report any new dark area that appears in a nail plate and does not resolve within 4 to 6 weeks. This could be a warning sign of melanoma, a potentially serious form of skin cancer. Melanoma may present as a dark streak in a nail plate that extends onto the cuticle. A biopsy is mandatory, and surgical excision is the standard treatment.*
*Disclaimer, results may vary from person to person.