3. DISCUSSION
Ulcerative colitis (UC) is a chronic non-specific inflammatory bowel disease characterized by recurrent symptoms such as abdominal pain, diarrhea, and bloody mucous stools. The disease typically follows a chronic course with alternating periods of flare-ups and remission, and in some cases, symptoms may persist and gradually worsen. UC usually begins in the rectum and progresses proximally, potentially affecting the entire colon, including the terminal ileum. Appendiceal orifice inflammation (AOI) refers to congestion, erosion, and ulcers at the appendiceal orifice. When AOI co-occurs with UC, its inflammatory characteristics resemble the pathological features of UC. There is increasing evidence to suggest that AOI represents a skip lesion in the mucosa of UC [1]. Research indicates that AOI is more common in UC patients with mild to moderate distal colonic involvement [2]. However, retrospective studies have shown conflicting results, with some suggesting that AOI is more prevalent in moderate to severe UC, possibly serving as a marker of active disease and an indicator of disease severity [3].
The presence of AOI in UC patients has been associated with differing outcomes and responses to treatment. Wu and colleagues conducted a retrospective study involving 202 UC patients, of which 116 had AOI. They found a significant difference in the cumulative risk of endoscopic complete remission between the AOI and non-AOI groups, indicating a lower rate of endoscopic complete remission in UC patients with AOI [4]. In a long-term follow-up study by Oh and colleagues involving 318 UC patients, 140 of whom had AOI, the AOI group demonstrated a lower rate of endoscopic complete remission compared to the non-AOI group. However, there were no significant differences between the two groups in terms of other clinical parameters, including the use of biologics, hospitalization rates, and proximal disease extension [5]. Conversely, a retrospective analysis by Kyong and colleagues, involving 376 UC patients with an average follow-up time of 66.1 months, revealed no significant differences between the AOI and non-AOI groups in terms of endoscopic remission, hospitalization rates, recurrence rates, or the use of corticosteroids, immunosuppressants, and biologics [6]. Therefore, the role of AOI in predicting the prognosis of UC patients remains inconclusive.
Pathologically, AOI does not possess specific characteristics. A study analyzing 26 cases with histological abnormalities at the appendiceal orifice found active inflammation in 12 cases, chronic active inflammation in 13 cases, and one case resembling collagenous colitis. Additionally, eight patients with inflammation in other biopsy samples were eventually diagnosed with ulcerative colitis, with none of the patients isolated to the appendiceal orifice showing clinical symptoms during follow-up. As such, isolated inflammation of the appendiceal orifice mucosa should not be regarded as a sign of inflammatory bowel disease progression or as a distinguishing feature of other chronic colonic inflammations [7]. Nevertheless, while AOI is not uncommon in UC patients, it is often reported as a manifestation of ”skip inflammation” within UC, and cases of isolated AOI are rarely reported.
Although this case is an isolated instance, it is noteworthy due to its complete follow-up data. The patient initially presented with isolated AOI at disease onset, exhibiting symptoms such as abdominal pain and altered bowel habits. Pathological biopsy results indicated acute cryptitis, and treatment with mesalazine resulted in significant symptom relief and improved endoscopic findings. Subsequent symptom recurrence, followed by reinitiation of treatment, also led to noticeable improvements in symptoms and endoscopic appearance. Consequently, based on symptoms, endoscopic findings, histopathology, and treatment response, the patient was diagnosed with UC, and mesalazine treatment proved effective. This case highlights that UC can occasionally present as isolated AOI without other manifestations of gastrointestinal involvement. Clinical symptom variations aligned with endoscopic changes in AOI, suggesting that AOI can serve as an indicator of UC disease activity. The patient has been followed up for over four years with no evidence of other colonic involvement. Future follow-ups will monitor for potential involvement of other colonic segments.