An Unusual Case of Appendicitis Entrapped Within a Spigelian Hernia.

Acute appendicitis within a Spigelian hernia is a rare clinical entity that may present with atypical symptoms, resulting in diagnostic delay and complex operative decision-making. Previously reported cases have most commonly presented with localized right lower quadrant pain, abdominal wall masses, incarceration, bowel obstruction, or strangulation. Spigelian hernias occur along the semilunar line and may contain intra-abdominal structures, including the appendix, resulting in non-classic symptoms of appendicitis. We report a case of a 52-year-old woman with a history of cerebrovascular accident with residual left-sided weakness, prior laparotomy and colostomy following a gunshot wound to the left lower quadrant (2012), and atrial fibrillation with poor adherence to apixaban, who presented with progressive bilateral lower extremity pain and right lower quadrant pain radiating to the groin, with the atypical lower extremity symptoms initially prompting neurologic and musculoskeletal evaluation and delaying recognition of the underlying abdominal pathology. Initial vital signs were notable for mild tachycardia, and laboratory evaluation demonstrated mild leukocytosis. Over approximately one month, her progressive lower extremity pain was initially attributed to neurologic or musculoskeletal pathology, resulting in nondiagnostic spinal imaging before CT of the abdomen and pelvis established the diagnosis. CT imaging of the abdomen and pelvis ultimately revealed a right Spigelian hernia containing an inflamed appendix, consistent with acute appendicitis within the hernia sac. She underwent robotic appendectomy and hernia repair with mesh placement. Intraoperatively, a suppurative appendix within a 4-cm Spigelian hernia was confirmed. Her postoperative course was complicated by a superficial fluid collection managed with intravenous clindamycin and piperacillin-tazobactam for three days, with subsequent clinical improvement. This case is notable for the atypical presentation and resulting diagnostic delay. It highlights the importance of considering abdominal wall hernias and anatomic displacement of intra-abdominal structures in patients with persistent groin or lower quadrant pain, particularly when neurologic or musculoskeletal evaluation is unrevealing. Cross-sectional imaging remains essential for identifying uncommon hernia-related causes of appendicitis.