Differential Diagnosis for Black Marks on Finger Nails
Single Most Likely Diagnosis
- Melanonychia: This condition is characterized by a black or brown streak or spot on the nail plate, often due to an increase in melanin production. It's a common and usually benign condition, but it can be a sign of nail melanoma in rare cases.
Other Likely Diagnoses
- Nail Trauma: Injury to the nail can cause bleeding under the nail, leading to black marks or discoloration.
- Fungal Infections: Certain fungal infections, such as onychomycosis, can cause nail discoloration, including black marks.
- Nail Pigmentation due to Medication: Some medications, like minocycline or antimalarials, can cause pigmentation changes in the nails, including black marks.
Do Not Miss Diagnoses
- Subungual Melanoma: A type of skin cancer that can present as a black mark under the nail. It's crucial to diagnose and treat early to prevent metastasis.
- Subungual Hematoma: Bleeding under the nail, which can be caused by trauma and may appear as a black mark. In rare cases, it can be a sign of an underlying condition that needs medical attention.
Rare Diagnoses
- Addison's Disease: A rare endocrine disorder that can cause hyperpigmentation, including black marks on the nails.
- Peutz-Jeghers Syndrome: A genetic disorder characterized by the development of benign polyps in the gastrointestinal tract and an increased risk of certain cancers. It can also cause nail pigmentation, including black marks.
- Laugier-Hunziker Syndrome: A rare condition characterized by hyperpigmentation of the nails, skin, and mucous membranes, which can include black marks on the nails.