eP566 - Free Prize Inside: Amyand Hernia Containing Perforated Cecum and Low-grade Appendiceal Mucinous Neoplasm

Purpose/Background: A 76-year-old male with recurrent right inguinal hernia presented with 4 days of diarrhea. Vitals were normal, and abdomen was unremarkable. He had a large right scrotal hernia, which was firm, nontender, without skin changes. WBC was 14,000/uL, and he was anemic to hemoglobin 8 g/dL. GI PCR was negative. CT revealed large right scrotal hernia containing cecum and terminal ileum, a large fluid collection with punctate air concerning for contained perforation, a smaller collection consistent with hydrocele, and no obstruction. Imaging from 4 years prior during admission for cellulitis was concerning for appendiceal mucocele, and he was recommended colonoscopy and right hemicolectomy. He was lost to follow-up.Methods/Interventions: He had antibiotics and mechanical and antibiotic bowel preparation. Diagnostic laparoscopy revealed herniation of cecum, appendix, and ileum. Cytology of turbid fluid revealed inflammation, no mucin or malignant cells. Open inguinal incision was made, prior mesh was removed, and the hernia sac was opened. Bowel was delivered, and ileocecectomy was performed with primary side-to-side anastomosis. The appendix remained intact, and a punctate hole was identified in the cecum adjacent to the appendiceal orifice. Scrotal counter incision released purulence and stool. Orchiectomy and hydrocelectomy were performed, and the scrotum was debrided. A penrose drain was placed through the two incisions, and primary tissue repair of the inguinal hernia was performed with a second subcutaneous drain.Results/Outcomes: Pathology revealed low-grade appendiceal mucinous neoplasm (LAMN) extending into the lamina propria. Appendix was 6.5 cm long, 9-14mm diameter with wall thickening 3-5 mm, and the lumen was filled with gelatinous mucin. Resection margins were negative for tumor, and 1/1 lymph node negative for tumor. The lesion was pTis (LAMN) pN0. The abscess specimen contained gangrenous, necrotic tissue, marked acute and chronic fibrosis, and atrophic change. Fluid revealed acute inflammation without mucin or malignant cells. He was discharged home with plans for outpatient colonoscopy several months post-operatively given the increased risk of synchronous lesions in patients with LAMN.Conclusion/

Discussion: LAMN, previously known as mucocele, is a well-differentiated, low-grade dysplastic neoplasm of the appendiceal mucosa. Grossly, the appendiceal lumen is noted to be filled with gelatinous mucin with mild cytologic atypia. InpTis cases, there is lack of tumor infiltration past the muscularis propria, Non-ruptured, localized LAMN can typically be managed with appendectomy alone with an intact cyst. Further surveillance is not indicated, as pTis LAMNs rarely recur. Management of T4a LAMN is ill-defined and may require further resection and/or cytoreductive therapy.

LAMN symptoms may have been masked by hernia symptoms, even prior to cecal rupture, which was most likely secondary to closed loop obstruction at the hernia neck. This highlights the importance of close follow-up, as workup for the LAMN should have been years earlier, when it was first noted on CT.

A multidisciplinary approach including colorectal surgery, surgical oncology, and urology was used both pre- and intra-operatively. The hernia was primarily repaired, and drains were placed given extensive contamination. This atypical case required complex decision-making due to the location of the LAMN within the hernia sac, adjacent cecal perforation, and gross contamination of the scrotum.Figure 1June 2023 CT Scan with large fluid collection with punctate air concerning for contained perforation, a second smaller collection consistent with hydrocele, and no evidence of obstruction