Differential Diagnosis of Centrifugal versus Centripetal Rashes
Single Most Likely Diagnosis
- Tinea corporis (ringworm): A centrifugal rash that starts as a small, itchy, red patch and gradually spreads outward in a circular pattern, often with a clear center. This is a common and classic example of a centrifugal rash.
- Contact dermatitis: A centripetal rash that typically starts at the site of contact with an allergen or irritant and may spread inward, often with a clear border.
Other Likely Diagnoses
- Eczema (atopic dermatitis): A centripetal rash that often starts on the face, neck, or extremities and can spread inward, characterized by itchy, inflamed skin.
- Psoriasis: A centrifugal rash that can start as a small, scaly patch and spread outward, often with a well-defined border.
- Pityriasis rosea: A centrifugal rash that starts with a herald patch, followed by a secondary eruption of smaller patches that spread outward from the center of the body.
Do Not Miss Diagnoses
- Lyme disease: A centrifugal rash (erythema migrans) that can be a sign of early Lyme disease, characterized by a expanding red patch with a clear center.
- Meningococcemia: A centripetal rash that can be a sign of life-threatening meningococcemia, characterized by a rapidly spreading, petechial rash.
- Toxic epidermal necrolysis (TEN): A severe, centripetal rash that can be a sign of a life-threatening drug reaction, characterized by widespread skin necrosis and detachment.
Rare Diagnoses
- Erythema marginatum: A centrifugal rash associated with acute rheumatic fever, characterized by a pink, ring-shaped rash that spreads outward.
- Sweet syndrome: A centripetal rash characterized by a sudden onset of fever, leukocytosis, and tender, erythematous skin lesions.
- Granuloma annulare: A centrifugal rash characterized by a ring-shaped lesion with a clear center, often on the hands or feet.