Sessile serrated adenoma/polyp leading to acute appendicitis with multiple pyogenic liver abscesses: A case report

Significance of the Entire Appendiceal Evaluation in the Diagnosis of Serrated Lesions, Low-Grade Appendiceal Mucinous Neoplasm, and Appendiceal Diverticulosis Disease

Objective

This study was conducted in order to investigate the significance of the entire appendiceal evaluation in the pathological diagnosis of appendiceal serrated lesions, low-grade appendiceal mucinous neoplasm (LAMN), and appendiceal diverticulosis disease (ADD).

Methods

A total of 702 appendectomy specimens diagnosed from 2017 to 2020 were reviewed retrospectively. The specimens were divided into two groups according to the different sampling procedures. In group 1, the vast majority of 337 specimens were partially submitted by routine sampling within 18 months from October 2017 to March 2019. In group 2, 365 of specimens were entirely submitted and examined within 18 months from April 2019 to October 2020. The incidence and pathological features of serrated lesions, LAMN, and ADD in the two groups were compared and analyzed. The clinicopathological characteristics between different entities were also studied.

Results

Forty appendiceal serrated lesions, 8 LAMNs, and 21 diverticula were accidentally detected in 702 appendectomy specimens. As compared with group 1, the incidence of appendiceal serrated lesions in group 2 was significantly increased (9.3% vs. 1.8%, P < 0.01), especially for the serrated lesions without dysplasia (7.4% vs. 1.2%, P < 0.01). The entire sampling revealed that loss of lamina propria and replacement with dysplastic mucinous epithelium were statistically significantly associated with LAMN rather than serrated lesions and ADD (P < 0.01 and P < 0.01, respectively). Mural mucin deposition and fibrosis were useful features to distinguish LAMN from simple serrated lesions (P < 0.01 and P < 0.05, respectively), but mucin deposition was useless for the distinction between LAMN and ADD (P > 0.05) or serrated lesions combined with ADD.

Conclusion

Our study highlights the importance and necessity of careful gross assessment and histologic examination of the entire appendectomy specimen, since the association with unexpected appendiceal lesions is significant and cannot be ignored. The entirely submitted appendix is more sensitive for the detection of appendiceal serrated lesions. In addition, thorough examination and evaluation are essential to distinguish the key pathological features between appendiceal serrated lesions, LAMN, and ADD.

Incidental Finding of Diverticulosis of the Appendix with Sessile Serrated Adenoma

Diverticulosis and sessile serrated adenomas of the colon are common findings on routine colonoscopy. However, diverticulosis of the appendix is rare and is usually only discovered due to conversion to diverticulitis or as an incidental finding. Diverticulitis of the appendix can present as appendicitis but is associated with more risks. A pathology report is important in diverticulosis of the appendix due to the association with malignancy. This case report reviews a 52-year-old female who presented to the emergency department with right lower quadrant pain who was diagnosed with acute appendicitis and was incidentally found to have diverticulosis of the appendix with a sessile serrated adenoma.

A rare trigger for acute appendicitis leading to small bowel obstruction: traditional serrated adenoma of the appendiceal foramen

This is the first documented case of traditional serrated adenoma (TSA) of the appendiceal foramen that triggered acute appendicitis resulting in small bowel obstruction (SBO). An 88-year-old Japanese man presented with abdominal pain, distension, and appetite loss. Computed tomography demonstrated distended ileum adherent to cecum with thickened walls. He was diagnosed with SBO, and open ileoceal resection was eventually performed. Pathological examination revealed that a pedunculated polyp had obstructed the appendiceal foramen and triggered acute appendicitis, thus leading to SBO. Histopathological examination of the polyp revealed that the long fronds of the adenoma were lined by dysplastic epithelial cells, which is a characteristic feature of TSA. This case report illustrates that a tiny TSA can trigger the obstruction of the appendiceal foramen and lead to acute appendicitis and SBO. We underline the need for the resection of the polyps in this region regardless of their size.