What is the cause of a truncal rash?

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Last updated: March 21, 2025View editorial policy

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Differential Diagnosis for Truncal Rash

  • Single most likely diagnosis
    • Eczema (atopic dermatitis): This is a common condition that often presents with a truncal rash, characterized by itchy, inflamed skin. The rash can be acute or chronic and is often seen in individuals with a history of allergies or asthma.
  • Other Likely diagnoses
    • Psoriasis: A chronic skin condition that can cause a truncal rash, typically appearing as red, scaly patches. It can be associated with other symptoms like joint pain.
    • Contact dermatitis: This occurs when the skin comes into contact with an irritant or allergen, leading to a rash. The truncal area can be affected if the individual has come into contact with such substances on their torso.
    • Tinea corporis (ringworm): A fungal infection that can cause a rash on the trunk, characterized by ring-shaped lesions.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • Meningococcemia: Although rare, this condition can present with a rash and is life-threatening. It's caused by a bacterial infection that can lead to meningitis or sepsis.
    • Rocky Mountain spotted fever: A tick-borne illness that can cause a rash, fever, and headache. It's critical to diagnose early as it can be fatal if not treated promptly.
    • Lyme disease: Another tick-borne illness that can cause a rash (often a "bull's-eye" rash), fever, and other symptoms. Early diagnosis and treatment are crucial to prevent long-term complications.
  • Rare diagnoses
    • Pityriasis rubra pilaris: A rare skin disorder that can cause a truncal rash, characterized by small, pointed bumps and reddish-orange patches.
    • Keratosis pilaris: A condition that causes small, rough patches on the skin, which can sometimes appear on the trunk.
    • Sarcoidosis: A disease that can affect multiple parts of the body, including the skin, and cause a truncal rash among other symptoms.

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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