Differential Diagnosis for Dark Lines in Nails
Single Most Likely Diagnosis
- Melanonychia: This condition is characterized by a brown or black pigmentation of the nail plate due to the presence of melanin. It is the most common cause of dark lines in nails and can be caused by a variety of factors including trauma, infection, or as a side effect of certain medications.
Other Likely Diagnoses
- Nail Trauma: Trauma to the nail can cause bleeding under the nail plate, leading to the appearance of dark lines.
- Fungal Infections: Fungal infections such as onychomycosis can cause changes in nail color, including the appearance of dark lines.
- Nail Pigmentation due to Medications: Certain medications, such as chemotherapy agents, can cause changes in nail pigmentation, leading to dark lines.
Do Not Miss Diagnoses
- Subungual Melanoma: Although rare, subungual melanoma is a type of skin cancer that can present as a dark line in the nail. It is crucial to not miss this diagnosis as it can be life-threatening if left untreated.
- Endocarditis: In rare cases, dark lines in the nails can be a sign of endocarditis, a serious infection of the heart valves.
Rare Diagnoses
- Addison's Disease: This rare endocrine disorder can cause changes in skin and nail pigmentation, including the appearance of dark lines in the nails.
- Peutz-Jeghers Syndrome: This rare genetic disorder is characterized by the presence of dark blue or brown macules on the skin and mucous membranes, and can also cause dark lines in the nails.
- Laugier-Hunziker Syndrome: This rare condition is characterized by the presence of dark brown or black macules on the skin and mucous membranes, and can also cause dark lines in the nails.