Differential Diagnosis for Scalp Crusted Lesions on Roots of Hairs with Discharges

• Single most likely diagnosis:
  • Tinea capitis (Ringworm of the scalp): This fungal infection is common in children and can cause crusted lesions on the scalp, especially at the roots of hairs, accompanied by discharge. It's highly contagious and can lead to hair loss if not treated.
• Other Likely diagnoses:
  • Folliculitis: An inflammatory condition affecting the hair follicles, which can be caused by bacterial, viral, or fungal infections. It presents with crusty lesions and discharge around the hair roots.
  • Impetigo: A highly contagious skin infection that can affect the scalp, causing crusted lesions and discharge. It's more common in children.
  • Seborrheic dermatitis: Although it typically presents with a greasy, scaly scalp, in some cases, it can cause crusted lesions, especially if secondary infected.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Kerion: A severe form of tinea capitis that can cause significant inflammation, pus, and potentially lead to scarring and permanent hair loss if not promptly treated.
  • Meningitis (in the context of a scalp infection spreading): Although rare, any infection of the scalp can potentially spread to the meninges if it reaches the bloodstream, making it crucial to monitor for signs of meningitis, especially in severe cases.
• Rare diagnoses:
  • Favus (Tinea favosa): A chronic and contagious form of tinea capitis caused by Trichophyton schoenleinii, characterized by the formation of yellowish crusts (scutula) around the infected hairs.
  • Dissecting cellulitis of the scalp: A rare condition characterized by recurring, painful, inflamed nodules and abscesses on the scalp, which can lead to scarring alopecia. It's part of the follicular occlusion triad, along with acne conglobata and hidradenitis suppurativa.