Differential Diagnosis for a 65-year-old Male with a Dark Toenail from Training for a Marathon
- Single most likely diagnosis
- Subungual hematoma: This condition is caused by bleeding under the nail, often due to repetitive trauma, such as running. The dark coloration is a result of the blood accumulation. Given the patient's recent increase in running activity while training for a marathon, this diagnosis is highly plausible.
- Other Likely diagnoses
- Fungal infection (onychomycosis): This is a common condition in athletes, especially those who engage in activities that involve repeated trauma to the toes, such as running. It can cause discoloration of the nail, including darkening.
- Nail melanonychia: This condition is characterized by a brown or black pigmentation of the nail, which can be caused by various factors, including trauma. While less common than subungual hematoma, it is still a consideration in athletes.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Subungual melanoma: Although rare, this is a potentially deadly condition that can present with a darkened nail. It is crucial to consider this diagnosis, especially in older adults, to ensure timely referral and treatment if necessary.
- Squamous cell carcinoma: This type of skin cancer can very rarely present under the nail and cause discoloration. Early detection is key to effective treatment.
- Rare diagnoses
- Subungual glomus tumor: A rare, benign tumor that can cause nail discoloration and pain. It is an uncommon condition but should be considered if other diagnoses are ruled out.
- Subungual keratoacanthoma: A rare, benign tumor that can cause nail elevation and discoloration. It is less common than other conditions listed but remains a possibility in the differential diagnosis.