What is the cause of a macular, red, non-blanching rash (macula refers to a flat, red patch on the skin)?

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Differential Diagnosis for Macula Red Non-Blanching Rash

  • Single most likely diagnosis
    • Petechiae: This is the most likely diagnosis due to the description of a macula red non-blanching rash, which is characteristic of petechiae. Petechiae are small, pinpoint spots that occur due to minor hemorrhages from broken capillary blood vessels.
  • Other Likely diagnoses
    • Purpura: This condition is similar to petechiae but involves larger areas of bleeding under the skin, which could also present as a macula red non-blanching rash.
    • Ecchymosis: Although typically larger than petechiae, ecchymosis (bruises) can initially present as a non-blanching red rash before turning purple.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • Meningococcal sepsis: This is a life-threatening condition that can cause a non-blanching rash, often described as petechial or purpuric. It's crucial to consider this diagnosis, especially in patients with fever, shock, or other signs of severe illness.
    • Rocky Mountain spotted fever: Another severe infection that can present with a non-blanching rash, along with fever and other systemic symptoms.
  • Rare diagnoses
    • Henoch-Schönlein purpura (HSP): A form of vasculitis that can cause a non-blanching rash, typically accompanied by joint pain, abdominal pain, and kidney involvement.
    • Thrombocytopenia: Certain conditions leading to low platelet counts can result in petechiae or purpura, presenting as a non-blanching rash.
    • Vasculitis: Other forms of vasculitis, such as microscopic polyangiitis or granulomatosis with polyangiitis, can also cause non-blanching rashes, although they are less common.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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