Differential Diagnosis for Single Bordered Round Rash on Back of 5 yo Child

• Single Most Likely Diagnosis
  • Tinea corporis (Ringworm): This is a common fungal infection in children, characterized by a round, single-bordered rash that can appear on various parts of the body, including the back. The rash typically has a clear center and a raised, scaly border.
• Other Likely Diagnoses
  • Eczema (Atopic Dermatitis): While eczema can present with various morphologies, a round, single-bordered rash could be a manifestation, especially if it's a localized form. Itching is a common symptom.
  • Psoriasis: Though less common in children, psoriasis can present with well-defined, round plaques. The presence of other symptoms like scaling and nail changes might support this diagnosis.
  • Pityriasis rosea: This condition often starts with a single, large patch called a "herald patch," followed by a secondary eruption of smaller patches. The herald patch can sometimes resemble a single-bordered round rash.
• Do Not Miss Diagnoses
  • Lyme Disease: Caused by the bacterium Borrelia burgdorferi, transmitted by tick bites. The initial stage of Lyme disease can present with a characteristic "bull's-eye" rash (erythema migrans), which is a round, expanding rash with a central clearing. Missing this diagnosis can lead to serious complications if not treated promptly.
  • Erythema multiforme: A skin condition characterized by target lesions, which can sometimes appear as round, single-bordered rashes. It's crucial to recognize this condition due to its potential association with infections and medications.
• Rare Diagnoses
  • Granuloma annulare: A benign skin condition that can appear as a ring of small bumps, typically on the hands and feet but can occur elsewhere, including the back. It's less common in children.
  • Sarcoidosis: A condition that can affect multiple parts of the body, including the skin, where it may cause lesions that can appear as round, single-bordered rashes. It's rare in young children.