Differential Diagnosis for a 4-week-old Infant with Emesis and Abdominal Mass
- Single most likely diagnosis:
- Hypertrophic Pyloric Stenosis (HPS): This condition is characterized by the thickening of the pylorus muscle, leading to gastric outlet obstruction. The presentation of emesis after feeding and a palpable, firm, and nontender mass in the mid-upper abdomen (often described as an "olive") is classic for HPS, especially in infants around this age.
- Other Likely diagnoses:
- Gastroesophageal Reflux Disease (GERD): While GERD can cause emesis, it typically does not present with a palpable abdominal mass. However, it's a common condition in infants and could be considered if the mass is not consistently palpable or if other symptoms of GERD are present.
- Intussusception: This is a condition where a part of the intestine telescopes into another, which can cause abdominal masses and vomiting. However, it usually presents with intermittent abdominal pain (colic) and currant jelly stool, which are not mentioned here.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Midgut Volvulus: A condition where the intestine twists around its mesenteric axis, leading to bowel ischemia. It's a surgical emergency and can present with bilious vomiting and abdominal tenderness, although a mass might not always be palpable.
- Intestinal Obstruction: Due to various causes like atresias, stenosis, or other congenital anomalies. These conditions can present with vomiting and abdominal distension but might not always have a palpable mass.
- Rare diagnoses:
- Abdominal Neuroblastoma: A type of cancer that can present as an abdominal mass. While it's rare, especially in this age group, it's crucial to consider in the differential diagnosis of any abdominal mass in a child.
- Congenital Anomalies (e.g., duodenal atresia, gastric duplication): Various congenital anomalies can cause vomiting and abdominal masses in infants. Each has distinct features and may require specific diagnostic tests for identification.