Differential Diagnosis for Black Toe

• Single most likely diagnosis
  • Trauma (e.g., stubbing or crushing injury): This is often the most common reason for a black toe, as it can cause bruising and bleeding under the nail.
• Other Likely diagnoses
  • Fungal infection (e.g., onychomycosis): Fungal infections can cause discoloration of the toenail, including blackening.
  • Poor circulation: Reduced blood flow to the toes can cause tissue damage and discoloration, leading to a black toe.
  • Diabetes: People with diabetes are prone to poor circulation and nerve damage, which can lead to black toes.
  • Tobacco use: Smoking can reduce blood flow to the extremities, increasing the risk of black toes.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Embolism (e.g., pulmonary or peripheral): An embolism can cause sudden and severe reduction in blood flow, leading to tissue death and blackening of the toe.
  • Atherosclerosis: Severe atherosclerosis can cause reduced blood flow to the toes, leading to tissue damage and discoloration.
  • Sepsis: In rare cases, a black toe can be a sign of sepsis, a life-threatening condition that requires immediate medical attention.
• Rare diagnoses
  • Melanoma: In rare cases, a black toe can be a sign of melanoma, a type of skin cancer.
  • Arsenic poisoning: Exposure to arsenic can cause discoloration of the skin and nails, including blackening of the toes.
  • Cholesterol embolism: This is a rare condition where cholesterol crystals break loose and travel to the toes, causing blockages and tissue damage.