Differential Diagnosis for Petechial Rash on the Leg
Single Most Likely Diagnosis
- Idiopathic Thrombocytopenic Purpura (ITP): This condition is characterized by low platelet count, leading to petechiae, purpura, and bruising. It is a common cause of petechial rash, especially in children and young adults.
Other Likely Diagnoses
- Vasculitis: Conditions like leukocytoclastic vasculitis can cause petechial rashes due to inflammation of small blood vessels.
- Infection: Bacterial, viral, or fungal infections (e.g., meningococcemia, Rocky Mountain spotted fever) can lead to petechial rashes.
- Medication-induced thrombocytopenia: Certain medications can cause a decrease in platelet count, resulting in petechiae.
- Trauma: Physical injury can cause petechial rashes, especially if there is significant bruising or bleeding under the skin.
Do Not Miss Diagnoses
- Meningococcemia: A life-threatening infection that can cause petechial rash, especially in children and young adults. Prompt recognition and treatment are crucial.
- Disseminated Intravascular Coagulation (DIC): A condition characterized by widespread clotting and bleeding, which can cause petechial rash, among other symptoms.
- Thrombotic Thrombocytopenic Purpura (TTP): A rare blood disorder that can cause petechial rash, along with other symptoms like fever, weakness, and neurological abnormalities.
Rare Diagnoses
- Henoch-Schönlein Purpura (HSP): A form of vasculitis that can cause petechial rash, abdominal pain, and joint pain, typically in children.
- Ehlers-Danlos Syndrome: A genetic disorder that can cause fragile blood vessels, leading to petechial rashes and easy bruising.
- Scurvy: A condition caused by vitamin C deficiency, which can lead to petechial rash, among other symptoms like fatigue and joint pain.