Differential Diagnosis for Inner Lip Bruise in a 10-Month-Old

Single Most Likely Diagnosis

• Accidental trauma: This is the most common cause of an inner lip bruise in a 10-month-old child, likely due to a fall or bumping into an object while learning to walk or crawl.

Other Likely Diagnoses

• Oral habits (e.g., sucking or biting the inner lip): Infants and toddlers often exhibit oral habits that can lead to bruising of the inner lip.
• Teething: The process of teething can cause irritation and bruising of the inner lip, especially if the child is biting down on the lip due to teething pain.
• Minor household accidents (e.g., hitting the lip on a table or chair): As children become more mobile, they are at increased risk of minor accidents that can result in bruising.

Do Not Miss Diagnoses

• Non-accidental trauma (child abuse): Although less likely, it is crucial to consider the possibility of child abuse, as bruising in unusual locations or patterns can be indicative of non-accidental injury.
• Bleeding disorder: A bleeding disorder, such as hemophilia or von Willebrand disease, could lead to easy bruising, including an inner lip bruise, even with minor trauma.
• Infection or abscess: Although rare, an infection or abscess in the oral cavity could cause swelling and bruising of the inner lip.

Rare Diagnoses

• Hematologic malignancies (e.g., leukemia): Certain blood cancers can increase the risk of bruising due to abnormalities in blood cell production.
• Vascular malformations: Rarely, a vascular malformation in the lip could lead to bruising or bleeding.
• Coagulopathy due to vitamin K deficiency: Newborns and young infants are at risk of vitamin K deficiency bleeding, which can manifest as bruising, although this is extremely rare in a 10-month-old child who has been receiving routine vitamin K supplementation.