Incidental histopathological findings in appendectomy specimens: A retrospective cohort study at a tertiary Center

Every year, millions of people undergo a routine surgery to remove their appendix, usually because the small, finger-like pouch attached to the large intestine has become painfully inflamed. For most, the procedure is a straightforward fix for an acute infection, and the removed organ is sent to a laboratory where a pathologist examines it under a microscope to confirm the diagnosis. However, the appendix is not always just a site of infection. Sometimes, hidden within the tissue, are unexpected discoveries—growths, lesions, or other conditions that were not suspected before the surgery. These incidental findings are rare, but they matter deeply because they can change a patient's future medical care, sometimes requiring further surgery or long-term monitoring. Understanding how often these surprises occur, what they look like, and who is most likely to have them helps doctors decide how carefully they must examine every removed appendix and how best to treat the patients afterward.

A team of researchers at King Saud University in Riyadh, Saudi Arabia, set out to map the landscape of these hidden discoveries. They looked back at the medical records of 1,502 patients who had their appendix removed at a major university hospital between February 2020 and December 2025. The team sorted every single case into one of three buckets: those with a standard, acute infection; those where the tissue looked perfectly healthy and normal; and those where the microscope revealed something else entirely. Their goal was to see how common these "other" findings were and to understand if factors like a patient's age, gender, or the reason for the surgery made a difference.

The results showed that while the vast majority of appendices were either infected or normal, a small but significant group of patients had unexpected findings. Out of the 1,502 records, 31 cases, or about 2.1 percent, contained these incidental discoveries. The most frequent surprise was a specific type of slow-growing growth called a low-grade appendiceal mucinous neoplasm, which accounted for nearly three-quarters of these unexpected cases. Other findings included small neuroendocrine tumors, endometriosis, and rare polyps. The researchers found that the likelihood of finding one of these surprises was not random; it was strongly tied to age. The average age of patients with these incidental findings was 55 years, compared to just 26 for those with a standard infection. In fact, the chance of finding an unexpected growth increased dramatically as patients got older, with the highest rate appearing in people over 65.

Interestingly, the study found that gender did not play a role in whether these hidden conditions were present. While women made up a large portion of the group with normal-looking appendices, the mix of men and women was roughly equal among those with the unexpected findings. The context of the surgery also mattered. When an appendix was removed as part of a larger operation for a different reason, rather than as a standalone emergency procedure, it was more likely to harbor one of these silent conditions. This suggests that when surgeons remove an appendix during another procedure, they are often taking out a healthy-looking organ that happens to contain a slow-growing lesion that would have gone unnoticed otherwise.

The clinical impact of these findings was tangible. In four cases out of 26 appendiceal neoplasms, the pathology report revealed that the growth had reached the edge of the removed tissue. This information was critical because it meant that for some patients, the initial surgery was not enough. Two patients in the study required a second, more extensive operation to ensure all the abnormal tissue was removed: one patient with a low-grade mucinous neoplasm and one with adenocarcinoma. The adenocarcinoma case underwent a larger section of the colon to be taken out because the first surgery had left a positive margin. These outcomes highlight that the routine examination of the appendix is not just a formality; it is a vital safety net that catches conditions early, preventing them from becoming more serious problems later.

The researchers noted that their hospital is a major referral center, which might mean they see more complex cases than a local community hospital would. This could explain why they found so many of the specific type of slow-growing mucinous growths compared to other studies that found more parasitic infections or simple inflammation. Despite this, the clear link between older age and these hidden findings stands out as a universal lesson. The study concludes that because these conditions are often silent and can be missed by the naked eye, every removed appendix deserves a careful look under the microscope. This diligence ensures that the few patients who need extra care receive it, turning a routine procedure into a powerful tool for long-term health.