Diaper Dermatitis: This is the most common cause of buttock erythema in neonates, resulting from prolonged contact with urine and feces, leading to skin irritation and inflammation.

Candidal Diaper Dermatitis: A fungal infection that can complicate diaper dermatitis, especially in areas that are warm and moist, leading to a more severe form of dermatitis.
Bacterial Diaper Dermatitis: Bacterial infections can also complicate diaper dermatitis, with common pathogens including Staphylococcus aureus and Streptococcus pyogenes.
Allergic Contact Dermatitis: An allergic reaction to components of the diaper or diaper wipes, which can cause erythema and skin irritation.

Child Abuse: Although rare, it is crucial to consider child abuse as a potential cause of buttock erythema, especially if the pattern of injury is suspicious or if there are other signs of neglect or abuse.
Staphylococcal Scalded Skin Syndrome (SSSS): A serious condition caused by staphylococcal toxins that can lead to widespread skin erythema and exfoliation, which can be life-threatening if not promptly treated.
Toxic Epidermal Necrolysis (TEN): A severe skin condition usually triggered by medications, leading to widespread skin necrosis and detachment, which is rare but potentially fatal.

Erythema Multiforme: An immune-mediated condition characterized by target lesions, which can occasionally present with buttock erythema, though it is less common in neonates.
Incontinentia Pigmenti: A genetic disorder that can cause skin lesions, including erythema, though it is very rare and typically associated with other systemic and dermatological findings.
Zinc Deficiency: A nutritional deficiency that can lead to skin lesions and erythema, including in the diaper area, though it is uncommon in neonates unless there is a specific dietary deficiency or underlying condition affecting zinc absorption.