What are the possible diagnoses for a 15-year-old patient presenting with left upper quadrant pain?

Differential Diagnosis of Left Upper Quadrant Pain in a 15-Year-Old

In a 15-year-old presenting with left upper quadrant pain, the primary considerations are splenic trauma, gastric pathology, pancreatic disease, and atypical appendicitis from intestinal malrotation, with CT abdomen and pelvis with IV contrast being the definitive diagnostic test. 1

Initial Clinical Assessment

The evaluation should focus on identifying specific clinical features that guide diagnosis and urgency:

• Trauma history is critical - In adolescents, splenic injury may present as left upper quadrant pain with referred left shoulder pain, hypovolemic shock, or generalized abdominal pain, particularly following motor vehicle accidents, sports injuries, or bicycle accidents 2

• Fever and leukocytosis indicate inflammatory or infectious processes requiring urgent imaging, with CT abdomen and pelvis with IV contrast rated 8/9 (usually appropriate) by the American College of Radiology 1

• Postprandial pain patterns suggest gastric or pancreatic pathology, with functional dyspepsia being common in this age group if structural abnormalities are excluded 1

• Acute onset with vomiting raises concern for pancreatitis, which is confirmed by serum amylase >4× normal or lipase >2× upper limit 1

Diagnostic Imaging Strategy

CT abdomen and pelvis with IV contrast is the preferred initial imaging modality, providing comprehensive assessment of all potential causes with excellent diagnostic accuracy 1:

• CT alters diagnosis in nearly half of cases and should not be dismissed as benign without imaging when clinical suspicion exists 1

• This modality comprehensively evaluates splenic pathology, pancreatic disease, gastric abnormalities, vascular conditions, and can detect unexpected findings including malrotation with atypical appendicitis 1, 3

• Plain radiography has very limited diagnostic value and is not recommended 1

• Ultrasound has limited utility in the left upper quadrant due to overlying bowel gas and rib shadowing, though it may identify splenic or renal pathology 1

Specific Diagnostic Considerations in Adolescents

Splenic Pathology

• Splenic trauma is a critical consideration in this age group, with mechanisms including sports injuries, bicycle accidents, and motor vehicle collisions 2

• Non-operative management is the mainstay in hemodynamically stable pediatric patients with splenic trauma, with success rates of 95-100% in urban pediatric hospitals 2

• Hemodynamic stability in children is defined as systolic blood pressure ≥90 mmHg plus twice the child's age in years (lower limit: 70 mmHg plus twice the age) 2

• Splenic torsion can present with left upper quadrant pain and may show a "whorled pedicle" or "upside down spleen" sign on CT imaging 4

Atypical Appendicitis

• Intestinal malrotation with left-sided appendicitis is a rare but critical diagnosis that presents as left upper quadrant pain in adolescents 3, 5

• This diagnosis requires high clinical suspicion, as atypical presentations may result in diagnostic and management delay, increasing morbidity and mortality 3

• CT imaging is essential for identifying both the malrotation and the inflamed appendix in an atypical location 3

Pancreatic Disease

• Pancreatitis in adolescents may present with left upper quadrant pain and vomiting 1

• Diagnosis requires serum amylase >4× normal or lipase >2× upper limit 1

• Pancreatic pseudocysts, including intrasplenic pseudocysts, can cause left upper quadrant pain and are identified on CT imaging 6

Gastric and Functional Disorders

• Functional dyspepsia is common in adolescents when structural abnormalities are excluded 1

• Testing for H. pylori and treating if positive is recommended by the American Gastroenterological Association, followed by acid suppression with PPIs if symptoms persist 1

Critical Pitfalls to Avoid

• Do not dismiss left upper quadrant pain without imaging when clinical suspicion exists, as CT alters diagnosis in 49% of patients with nonlocalized abdominal pain 1

• Consider atypical appendicitis in the differential diagnosis of left upper quadrant pain, particularly in adolescents, as intestinal malrotation may be asymptomatic until acute complications develop 3

• Assess for trauma history carefully, as the elastic pediatric rib cage may transmit force into the abdominal compartment, causing splenic injury without obvious external signs 2

• Intra-abdominal abscess from any source should be considered if pain is associated with fever or leukocytosis 1

Management Algorithm Based on Findings

If Trauma History Present:

• Assess hemodynamic stability using age-appropriate parameters 2
• Obtain CT abdomen and pelvis with IV contrast to evaluate for splenic injury 2, 1
• Hemodynamically stable patients with splenic trauma should be managed non-operatively regardless of injury grade 2

If Fever and Leukocytosis Present:

• Obtain CT abdomen and pelvis with IV contrast urgently 1
• Consider intra-abdominal abscess, appendicitis (including atypical location), or other infectious/inflammatory processes 1, 3

If Vomiting Present:

• Check serum amylase and lipase to evaluate for pancreatitis 1
• Provide supportive care with IV fluids, pain control, and antiemetics 1

If Postprandial Pain Without Alarm Features:

• Test for H. pylori and treat if positive 1
• Consider trial of PPI therapy for functional dyspepsia 1
• Endoscopy is required if alarm features present (weight loss, anemia, family history of GI malignancy) 1