Dark spots on toes can be a cause for concern, but are often harmless. Many different factors can lead to discoloration under or on the toenail, ranging from minor injuries to common infections. Understanding the various reasons behind these spots can help you determine when it is appropriate to monitor the situation at home and when professional medical guidance might be beneficial.
Common Reasons for Dark Spots
One frequent cause of a dark spot on a toe is a subungual hematoma, a bruise under the nail. This occurs when trauma, such as stubbing a toe, dropping an object on it, or wearing shoes that are too tight, causes blood vessels under the nail to break. The trapped blood then pools, leading to a dark, often purplish, black, or reddish-brown appearance. The discoloration from a subungual hematoma typically grows out with the nail over several months as the nail heals. It may also cause throbbing pain.
Another common reason for toenail discoloration is a fungal infection. Fungi, such as dermatophytes, yeast, or molds, can infect the nail, causing it to change color to yellow, brown, black, white, or green. Beyond discoloration, fungal infections can also thicken, embrittle, or misshape the nail, sometimes causing it to separate from the nail bed. An unpleasant odor may also be present.
An ingrown toenail can also result in dark discoloration. The inflammation and potential infection associated with an ingrown nail can cause redness, swelling, and pain around the affected area. If an infection develops, pus or bleeding may be present, and the nail might become warped or discolored.
Sometimes, a dark spot might simply be a benign mole or an area of hyperpigmentation. These can form under the nail or on the skin of the toe. Post-inflammatory hyperpigmentation can also occur as a temporary darkening of the skin after an injury or infection has healed. These benign pigmented lesions often appear as dark streaks (melanonychia) and are particularly common in individuals with darker skin tones.
When a Dark Spot Could Be Serious
While many dark spots are benign, a rare but serious cause is subungual melanoma, a type of skin cancer that develops under the nail. This condition typically presents as a dark brown or black streak, often running vertically from the base to the tip of the nail. Unlike a bruise, this discoloration may not grow out with the nail or change positions over time, though it might increase in size.
The spot may have an irregular shape, uneven color, or blurred borders. A particularly important indicator is Hutchinson’s sign, where the pigmentation extends from the nail plate onto the surrounding skin, such as the cuticle or nail fold. Other signs that may accompany subungual melanoma include the nail splitting, cracking, deforming, lifting from the nail bed, or the presence of bleeding, pain, or a nodule under the nail.
Recognizing When to See a Doctor
It is advisable to seek medical attention for a dark spot on your toe if you notice certain concerning changes. A healthcare provider should evaluate any spot that is changing in size, shape, or color, or if it is growing rapidly. A significant warning sign is the presence of a dark streak extending from the nail onto the surrounding skin, known as Hutchinson’s sign.
Consulting a doctor is also recommended if the spot is painful, bleeding, or oozing, or if it is accompanied by persistent swelling, redness, or warmth. If you cannot recall any injury that would explain the spot, or if the spot does not seem to grow out with the nail over several months, a professional opinion is warranted.
What Happens During a Doctor’s Visit
During a medical visit for a dark spot on your toe, the doctor will begin with a visual examination of the spot, the nail, and surrounding skin. They will also take a medical history, asking about past injuries, when the spot appeared, and your personal or family history of skin conditions or cancers.
A special magnifying tool called a dermatoscope may be used for a more detailed examination. This tool helps differentiate between benign causes like a hematoma and more serious conditions like melanoma. If a serious condition like melanoma is suspected, a biopsy may be necessary for a definitive diagnosis.
A biopsy involves taking a small tissue sample from the affected area for laboratory analysis. This procedure is typically performed under local anesthetic to numb the area. There are various biopsy techniques, and the choice depends on the specific location and nature of the suspected lesion. Depending on the findings, the doctor might refer you to a specialist, such as a dermatologist for skin conditions or a podiatrist for foot-specific issues. While some causes of dark spots are serious, most are benign, and professional evaluation provides clarity and peace of mind.