Seborrheic Dermatitis: This is a common condition in infants, characterized by a scalp rash that can be oily, yellow, and scaly. It's often seen in areas rich with sebaceous glands, like the scalp, and can be associated with cradle cap.

Atopic Dermatitis (Eczema): A chronic skin condition that can cause a scalp rash, often accompanied by itching. It's common in children and can be associated with other allergies or asthma.
Contact Dermatitis: An allergic reaction or irritation caused by something that came into contact with the scalp, such as shampoo, hair products, or even certain metals in hair clips.
Impetigo: A contagious bacterial infection that can cause a rash on the scalp, often with honey-colored crusts.
Ringworm (Tinea Capitis): A fungal infection of the scalp, which can cause patches of hair loss, redness, and scaling.

Meningitis: Although rare, a scalp rash could be a sign of meningitis, especially if accompanied by fever, irritability, and a bulging fontanelle in infants. Meningitis is a medical emergency.
Kawasaki Disease: An acute febrile illness that can present with a rash, among other symptoms like fever, conjunctivitis, and changes to the lips and oral cavity. It's crucial to diagnose early to prevent cardiac complications.
Child Abuse: In some cases, a scalp rash or injury could be a sign of non-accidental trauma. Healthcare providers must be vigilant for signs of abuse.

Langerhans Cell Histiocytosis: A rare disorder in which the body accumulates too many immature Langerhans cells, leading to lesions that can appear on the scalp, among other places.
Congenital Syphilis: A condition that occurs when a baby is born with syphilis, which can cause a variety of symptoms including rashes.
Sarcoidosis: Although extremely rare in infants, sarcoidosis can cause skin lesions, including on the scalp, as part of a systemic disease affecting multiple organs.