What is the likely diagnosis and treatment for a patient experiencing episodic left upper quadrant (LUQ) pain that wraps around the left rib cage, occasionally travels down the side and back of the ribs, is triggered by fatty or fried foods, and has stool that sticks to the toilet bowl?

Likely Diagnosis: Pancreatic Exocrine Insufficiency with Possible Underlying Pancreatic Pathology

The clinical presentation of episodic left upper quadrant pain triggered by fatty or fried foods, wrapping around the left rib cage with radiation to the back, combined with steatorrhea (stool sticking to toilet bowl indicating fat malabsorption), strongly suggests pancreatic exocrine insufficiency, potentially secondary to chronic pancreatitis or other pancreatic pathology. 1, 2

Clinical Reasoning and Differential Diagnosis

Primary Diagnostic Considerations

• Pancreatic pathology is the most likely diagnosis given the constellation of postprandial pain triggered specifically by fatty foods, left upper quadrant location with radiation to the back, and objective evidence of fat malabsorption (steatorrhea) 1, 2

• The pain pattern—episodic, triggered by fatty meals, radiating posteriorly—is characteristic of pancreatic disease rather than typical biliary colic, which classically presents in the right upper quadrant or epigastrium 2, 3

• Steatorrhea (stool that sticks to the toilet bowl due to high fat content) indicates pancreatic exocrine insufficiency with inadequate lipase secretion, strongly supporting pancreatic pathology over functional disorders 1

Alternative Diagnoses to Consider

• Splenic flexure pathology (diverticulitis or colitis) can cause left upper quadrant pain but would not explain the fat-triggered symptoms or steatorrhea 1

• Functional dyspepsia typically presents with postprandial pain but would not cause objective steatorrhea and is more commonly epigastric rather than left-sided 4

• Biliary disease (including left-sided biliary colic from gallstones) can cause postprandial pain with fatty food intolerance, but pain is characteristically right upper quadrant or epigastric, not left-sided 4, 2, 5

Diagnostic Workup Algorithm

Immediate Laboratory Testing

• Serum lipase and amylase to evaluate for acute or chronic pancreatitis, with diagnostic criteria being lipase >2× upper limit of normal or amylase >4× normal 1, 6

• Complete blood count to assess for leukocytosis suggesting inflammatory process 6

• Liver function tests (ALT, AST, alkaline phosphatase, GGT, bilirubin) to evaluate for hepatobiliary involvement 6

• Fecal elastase-1 to confirm pancreatic exocrine insufficiency (levels <200 μg/g indicate insufficiency) 1

• Hemoglobin A1c and fasting glucose to screen for diabetes mellitus, which commonly accompanies chronic pancreatitis 1

Imaging Strategy

• CT abdomen and pelvis with IV contrast is the preferred initial imaging modality, rated 8/9 (usually appropriate) by the American College of Radiology for left upper quadrant pain evaluation 1, 4

• CT provides comprehensive assessment of pancreatic parenchyma, ductal anatomy, calcifications (suggesting chronic pancreatitis), masses, pseudocysts, and splenic pathology 1, 7

• Abdominal ultrasound has limited utility for pancreatic visualization due to overlying bowel gas and rib shadowing, though it may identify gallstones or splenic pathology 1, 7

• If CT findings are equivocal and clinical suspicion for chronic pancreatitis remains high, MRCP (magnetic resonance cholangiopancreatography) provides superior ductal detail without radiation 1

Common Diagnostic Pitfalls to Avoid

• Do not dismiss left-sided pain as non-biliary without imaging—atypical presentations of gallstone disease can occur, though the left-sided location and steatorrhea make this less likely 4, 5

• Do not attribute steatorrhea to dietary factors alone—objective fat malabsorption requires investigation for pancreatic insufficiency, celiac disease, or small bowel pathology 4, 1

• Do not overlook chronic pancreatitis in the absence of alcohol history—other etiologies include genetic mutations, autoimmune pancreatitis, pancreatic duct obstruction, and idiopathic causes 1

• Do not confuse this presentation with functional dyspepsia—the presence of objective steatorrhea excludes purely functional disorders and mandates structural evaluation 4

Treatment Approach

If Chronic Pancreatitis is Confirmed

• Pancreatic enzyme replacement therapy (PERT) with enteric-coated preparations containing 25,000-40,000 units of lipase per meal, taken with all meals and snacks 1

• Proton pump inhibitor (PPI) therapy to optimize pancreatic enzyme activity by reducing gastric acid degradation of enzymes 4, 1

• Fat-soluble vitamin supplementation (vitamins A, D, E, K) due to malabsorption 1

• Pain management with non-opioid analgesics initially; avoid NSAIDs which can exacerbate pancreatic inflammation 4

• Dietary modification with small, frequent meals and moderate fat restriction (not severe restriction, as some fat is needed for nutrition) 1

• Smoking cessation and alcohol abstinence if applicable, as both accelerate disease progression 4

If Acute Pancreatitis is Identified

• NPO status with IV fluid resuscitation using lactated Ringer's solution 1

• Pain control with appropriate analgesics 1

• Antiemetics for nausea management 1

• Monitor for complications including pancreatic necrosis, pseudocyst formation, or systemic complications 1

If Imaging Reveals Alternative Pathology

• Splenic pathology may require hematology consultation or surgical evaluation depending on findings 1

• Pancreatic mass requires tissue diagnosis and oncology referral 1

• Biliary obstruction may require ERCP (endoscopic retrograde cholangiopancreatography) for stone extraction or stent placement 1

When to Consider Gastroenterology Referral

• Persistent symptoms despite initial management warrant subspecialty evaluation 4, 1

• Abnormal imaging findings including pancreatic masses, ductal abnormalities, or chronic pancreatitis changes require gastroenterology consultation 1

• Need for advanced diagnostic procedures such as endoscopic ultrasound (EUS) for tissue sampling or ERCP for therapeutic intervention 1

• Refractory pain may benefit from celiac plexus block or other advanced pain management strategies 4

Critical Warning Signs Requiring Urgent Evaluation

• Fever with abdominal pain suggests acute cholecystitis, pancreatitis, or intra-abdominal abscess requiring urgent imaging and possible surgical consultation 4, 1

• Jaundice indicates biliary obstruction or hepatobiliary pathology requiring urgent evaluation 6

• Severe unremitting pain may indicate pancreatic necrosis, perforation, or vascular catastrophe 1

• Signs of shock (hypotension, tachycardia, altered mental status) require immediate resuscitation and surgical consultation 8