Some causes of lesions, such as sores or blisters, on the head include allergies, fungal infections, viral infections and acne, states WebMD. Cysts that form around hair shafts can become infected and cause lesions. Skin cancers of the scalp include changing moles, open sores and skin irritations.
Fungal infections include ringworm on the scalp and in the hair. Ringworm includes raised areas that resemble worms; and, the ring-shape leaves an unaffected patch of skin in the center, notes WebMD. Ringworm is highly contagious; therefore, it must be treated in order to prevent extreme inflammation, scarring and potentially permanent loss of hair, advises Healthline.
Lesions and scabs on the scalp can itch, but scratching can cause infections, making the sores worse, explains Healthline. Sometimes the breakouts heal on their own or with over-the-counter remedies. However, if the lesions spread or become infected, medical attention is required.