Case Presentation: A 33-year-old man presented to the emergency department with sudden onset, severe abdominal pain radiating toward the back. Medical history included bipolar disorder treated with bupropion, sertraline, and lamotrigine. Surgical history included prior appendectomy. There was no history of sick contacts, alcohol use, gallstones, or peptic ulcer disease. On exam he was tachycardic with epigastric tenderness. Labs showed leukocytosis of 18,000 WBC/mL and mild lipase elevation of 105 U/L (upper limit of normal = 78 U/L). Abdominal ultrasound and chest X-rays were normal. Abdominal computerized tomography (CT) with contrast noted minimal nonspecific mesenteric edema without peripancreatic fat stranding. The patient was admitted to internal medicine with a diagnosis of acute pancreatitis. He was treated supportively and discharged home with mild improvement in symptoms.Five days after discharge, he was readmitted with recurrent severe abdominal pain. Serum lipase remained mildly elevated and abdominal CT was without abnormality. Symptoms persisted despite ongoing supportive care for presumed acute pancreatitis. Upper endoscopy was unremarkable. Eight days into his second hospitalization, the patient underwent CT chest for evaluation of transient hypoxia with elevated D-dimer, which incidentally showed evidence of T7-T8 discitis-osteomyelitis. The diagnosis was subsequently confirmed on magnetic resonance imaging (MRI). Blood cultures grew Streptococcus viridans. He was treated with 6 weeks of IV antibiotics and experienced symptomatic improvement within days of beginning appropriate therapy. Ultimately, his epigastric pain was determined to be abdominal wall pain due to T7 radiculopathy caused by vertebral osteomyelitis.

Discussion: Vertebral osteomyelitis is a life-threatening condition which carries high morbidity and mortality even with prompt diagnosis and treatment. However, the diagnosis is often delayed due to nonspecific patient presentation. Here we report a case of vertebral osteomyelitis with abdominal pain as the predominant symptom, leading to initial misdiagnosis of acute pancreatitis.The abdominal wall is innervated by nerves originating at approximately T7-T11. Thoracic spine pathology, such as osteomyelitis as in this case, is an uncommon cause of abdominal wall pain due to nerve root compression or irritation. Radicular causes of abdominal wall pain have rarely been reported to mimic intraabdominal pathology including cholelithiasis and chronic pancreatitis.This case illustrates an unusual etiology for a common presenting symptom and highlights cognitive biases that can impair diagnostic reasoning. In this case, confirmation bias and premature closure contributed to an early misdiagnosis of acute pancreatitis even though initial laboratory and imaging findings were nonspecific, and ultimately incidental to the diagnosis. Diagnostic momentum further contributed to ongoing treatment for acute pancreatitis upon the second hospital admission.

Conclusions: Abdominal pain is a common complaint encountered by hospitalists and has a broad differential diagnosis. Clinicians should consider abdominal wall pain in any patient with abdominal pain, particularly if clinical evaluation is not consistent with an intraabdominal etiology. Thoracic radiculopathy should particularly be considered in patients with neuropathic-type pain, sensory deficits on the abdominal wall, or suspected thoracic spine disease.