Falciform Ligament Appendagitis: A Rare Cause of Acute Epigastric Pain

Falciform ligament appendagitis is an exceedingly rare cause of acute abdominal pain resulting from inflammation and infarction of the falciform ligament's fatty appendage. Its presentation often mimics more common causes of acute abdomen, making diagnosis challenging. We report the case of a 36-year-old Bangladeshi male with no prior medical history who presented with a four-day history of severe epigastric pain radiating to the right upper quadrant (RUQ). Clinical examination revealed localized tenderness and a palpable soft, well-circumscribed swelling, with laboratory investigations within normal limits except for mild leukocytosis and a slightly elevated alanine aminotransferase (ALT). Initial ultrasound suggested a rectus sheath hematoma; however, contrast-enhanced CT imaging demonstrated a fat-density lesion adjacent to the falciform ligament with surrounding inflammatory stranding, consistent with falciform ligament appendagitis. The patient was managed conservatively with analgesia, intravenous fluids, and supportive care, resulting in progressive improvement and complete resolution of symptoms by hospital day 4 without surgical intervention.