What causes a pruritic rash with ecchymosis and bite marks?

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Last updated: February 19, 2025View editorial policy

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Differential Diagnosis for Bruised Rash with Bite Marks and Itchy

  • Single most likely diagnosis
    • Insect bites (e.g., bed bugs, mosquitoes, fleas): This is the most likely diagnosis due to the presence of bite marks and a bruised, itchy rash. The symptoms are consistent with an allergic reaction to insect bites.
  • Other Likely diagnoses
    • Allergic contact dermatitis: This condition could cause a bruised, itchy rash, especially if the patient has come into contact with an allergen or irritant.
    • Eczema (atopic dermatitis): Eczema can cause itchy, inflamed skin that may appear bruised, and can be exacerbated by scratching or skin irritation.
    • Scabies: Scabies is a parasitic infection that causes intense itching and a rash, and can be spread through skin-to-skin contact.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • Meningococcemia: This is a life-threatening infection that can cause a rash, and although it is unlikely, it is crucial to consider due to its high mortality rate if left untreated.
    • Rocky Mountain spotted fever: This tick-borne illness can cause a rash, fever, and headache, and can be fatal if not treated promptly.
    • Lyme disease: Lyme disease is a tick-borne illness that can cause a rash, fever, and other symptoms, and can lead to serious complications if left untreated.
  • Rare diagnoses
    • Leukocytoclastic vasculitis: This is a rare condition that causes inflammation of the blood vessels and can result in a bruised, itchy rash.
    • Erythema multiforme: This is a rare skin condition that can cause a bruised, itchy rash, and is often triggered by an infection or medication.
    • Cutaneous lymphoma: This is a rare type of cancer that can cause a bruised, itchy rash, and is often associated with other symptoms such as fever and weight loss.

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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