What is the concern for a 2-month-old child presenting for a well-check visit with a history of incomplete newborn screening, strabismus (crossed eyes), a reported abnormal growth on the buttock, and multiple mongolian spots on the buttock, back, and legs, without symptoms of vomiting or abdominal pain?

Differential Diagnosis for 2-Month-Old Child

Single Most Likely Diagnosis

• Normal Variation or Physiological Strabismus: This is a common condition in infants where their eyes may appear crossed due to the immature development of their eye muscles and the brain's ability to coordinate eye movements. The presence of multiple mongolian spots, which are benign and common in infants, especially those with darker skin, supports a benign condition.

Other Likely Diagnoses

• Congenital Strabismus: A condition where the eyes are misaligned due to issues with the eye muscles or nerves. This could be a concern given the mother's observation of crossed eyes.
• Mongolian Spots with Associated Conditions: While mongolian spots themselves are benign, their presence can sometimes be associated with other conditions, such as neurofibromatosis or other genetic syndromes, though this is less common.
• Umbilical Granuloma: The description of the "belly button part fell off" could indicate an umbilical granuloma, a small growth that can occur after the umbilical cord falls off, often due to irritation or infection.

Do Not Miss Diagnoses

• Retinoblastoma: Although rare, this is a serious eye cancer that can cause strabismus. Early detection is crucial for treatment and survival.
• Neurological Conditions (e.g., Hydrocephalus, Brain Tumors): These conditions can cause strabismus among other symptoms. While the child does not currently exhibit other symptoms like vomiting or abdominal pain, these conditions can sometimes present subtly in infants.
• Infection or Sepsis: The umbilical area issue could potentially be a sign of an infection, which in an infant could quickly escalate to sepsis, a life-threatening condition.

Rare Diagnoses

• Genetic Syndromes (e.g., Down Syndrome, Edwards Syndrome): Some genetic syndromes can present with strabismus, mongolian spots, and other physical anomalies. However, these are less likely without other significant developmental delays or physical findings.
• Tumors (e.g., Neuroblastoma): Though rare, tumors can cause a variety of symptoms including strabismus if they affect the nerves controlling eye movement, and abnormal growths can be a sign of such conditions.