S3402 Uncommon Culprit in Acute Pancreatitis: Atypical Mycoplasma pneumoniae Presentation Without Respiratory Symptoms

Introduction: Mycoplasma pneumoniae is a well-known cause of atypical pneumonia but can also lead to extrapulmonary complications in a notable proportion of cases. These may involve the neurologic, dermatologic, hematologic, and gastrointestinal systems. Among gastrointestinal presentations, pancreatitis is a particularly rare and often overlooked association. This case highlights an unusual presentation of suspected acute pancreatitis related to M. pneumoniae infection in the absence of respiratory symptoms, emphasizing diagnostic challenges and clinical implications. Case Description/Methods: A 63-year-old man with no significant medical history presented with 2 weeks of progressive abdominal pain, nausea, vomiting, chills, and decreased oral intake. He denied alcohol use, recent travel, or sick contacts. He was febrile (100.8°F) with mild epigastric tenderness. Labs revealed AST 177 U/L, ALT 185 U/L, ALP 183 U/L, lipase 246 U/L, and WBC 2.5 K/µL. Computed tomography abdomen and magnetic resonance cholangiopancreatography (MRCP) showed hepatic steatosis without pancreatitis or biliary obstruction. Broad infectious (HIV, cytomegalovirus, SARS-CoV-2, Influenza A/B, malaria, Campylobacter, Shiga toxin, Legionella, fungi, ova/parasites) and autoimmune panels (antinuclear antibody, dsDNA, SSA/SSB, anti-Scl-70, RNP, Smith, anti-Jo-1, anti-centromere B, AMA) were negative. Despite empiric antibiotics, he remained febrile. On hospital day 7, Mycoplasma pneumoniae IgM returned positive. He was started on azithromycin, then transitioned to doxycycline for suspected macrolide resistance. He defervesced within 48 hours and was discharged with outpatient follow-up. Discussion: Pancreatitis is an uncommon extrapulmonary manifestation of Mycoplasma pneumoniae, particularly in the absence of respiratory symptoms. Gastrointestinal involvement occurs in approximately 5–8% of extrapulmonary cases, but pancreatitis remains underrecognized. This case underscores the diagnostic challenges and healthcare burden of atypical infections, including delayed diagnosis, prolonged hospitalization, inappropriate antibiotic use, and extensive testing. The absence of radiologic findings despite elevated enzymes and symptoms illustrates how imaging may lag behind biochemical markers in infectious etiologies. Earlier recognition of M. pneumoniae as a potential cause of pancreatitis—even without pulmonary signs—could expedite therapy and reduce morbidity.