Differential Diagnosis for Black Line on Fingernail
- Single Most Likely Diagnosis + Melanonychia: This condition is characterized by a black or brown streak on the nail plate, often caused by activation or proliferation of melanocytes in the nail matrix. It's a common and usually benign condition.
- Other Likely Diagnoses + Nail trauma: A black line on the fingernail can result from trauma to the nail, such as a bruise or hematoma under the nail plate. + Nail fungus (onychomycosis): Fungal infections can cause discoloration, including black lines, on the nail. + Nail staining: Exposure to certain chemicals or substances can stain the nail, resulting in a black line.
- Do Not Miss Diagnoses + Subungual melanoma: Although rare, a black line on the fingernail can be a sign of subungual melanoma, a type of skin cancer that occurs under the nail. Early detection is crucial for treatment. + Endocarditis: In rare cases, a black line on the fingernail can be associated with endocarditis, an infection of the heart valves.
- Rare Diagnoses + Addison's disease: This rare endocrine disorder can cause hyperpigmentation, including dark lines on the nails. + Peutz-Jeghers syndrome: A rare genetic disorder characterized by intestinal polyps and mucocutaneous melanin deposits, which can cause dark lines on the nails. + Laugier-Hunziker syndrome: A rare condition characterized by hyperpigmentation of the nails, oral mucosa, and skin.