CP is a relatively rare disease that is still not well recognized by physicians and surgeons, and currently, fewer than 100 cases have been published in the literature [12]. In our study, most of the patients were very young, their median age was only 20 years old, and some of them were annoyed by this disease affecting their normal work and study status. Hence, we thought we should pay more attention to this disease. Here we shared the experience in our hospital to add more data.
The majority of the patients were male, which was in accordance with previous literature [6, 20, 21]. In 2012, Papaconstantinou et al. summarized the cases of CP [20], and most of the patients were older than 50 years of age, but later, Brunner et al. summarized that children or younger populations also would develop CP [2]. The laboratory, and imaging characteristics of CP were not that specific. A portion of them would have anemia and thrombocytosis, while leukocytosis or elevated hs-CRP was not that common. Additionally, we should be aware that a certain number of patients would be misdiagnosed with malignant lesions in contrast-enhanced CT or MRI, in which the rates were 26.32% and 13.64%, respectively. Rectal cancer usually presents as a mass and seldomly multiple polyps (unless familial adenomatous polyposis), and repeated biopsy does not support malignant changes. If differentiation is still difficult, then a large piece of the polyp should be resected to help make a diagnosis.
IBD is also an important differential diagnosis, especially in children: it was the initial diagnosis in 75% of the reports on children [22]. However, endoscopically, ulcerative colitis has background mucous change, while CP is usually characterized by multiple polyps covered by fibrinopurulent exudates with normal mucosa between the polyps, and they have different pathologic features.
The relationship between CP and mucosal prolapse syndrome (MPS) is still debated. Some patients with CP have symptoms of prolapse. Cambell et al. supposed that abnormal colonic motility may lead to prolapse of the mucosa at the apices of transverse mucosal folds and cause ischemic changes [10]. The pathology includes fibromuscular obliteration of the lamina propria, granulation tissue, and elongated, hyperplastic glands. These features can also appear in MPS. However, they have some differences. First, fibromuscular obliteration is more marked in cap polyposis; second, CP can be found in both the colon and rectum, while MPS is usually confined to the rectum; third, the two diseases have different endoscopic ultrasound sonography images, as CP shows significant thickening of the mucosa, whereas MPS has remarkable thickening of the submucous [21, 23, 24].
To date, there is no standard or optimal therapy for CP, as its cause remains unclear. On the strength of previously published literature, various kinds of treatments have been tried, including medical therapies (observation, steroids, aminosalicylates, infliximab, metronidazole, H. pylori eradication, and so on), and endoscopic and surgical resection. But the clinical outcomes were heterogeneous. Some patients had spontaneous remission, while some needed surgical resection and still experienced recurrence [6]. Some investigators believed that, in adults, polypectomy should be performed to alleviate symptoms. However, in children, medical treatments were preferred. If the disease persists or recurs with medical treatment, then we should consider resection [2, 25]. In our study, we further compared the long-term effectiveness of endotherapy and surgical resection, although with a small number of patients, we found that, the recurrence risk had no significant difference. However, we combined several different means of endotherapy or surgical resection in the analysis, and we think that if we could accumulate more patients, then maybe we can find a certain means of resection with the best short-term and long-term outcomes.
Based on the literature review[2, 6, 7, 9, 14–19, 26] and our own data, we thought that, if the patient was H. pylori positive, then H. pylori eradication combined with other therapies might be useful. There were 7 patients who were tested to have H. pylori, 5 of them had improvement after H. pylori eradication, the other two was lost. H. pylori negative, although various means tried, the outcome was not that good. Moreover, for those with rectal prolapse, if the situation of rectal prolapse was not treated, then CP seemed to recur repeatedly.
The goal of CP treatment is another question that we need to consider. During follow-up, some patients might have no symptoms, but the colonoscopy still showed polyps with smaller sizes (or recurrence of polyps). They felt very well, and did not want to see the doctors for further treatment at the moment. Should the patients receive treatments until the disappearance of all the polyps, until the disappearance of all the symptoms or until the symptoms do not influence the patient’s work and life? The above questions remain to be answered. The natural course of CP is largely unknown, and if asymptomatic or slightly symptomatic CP is left untreated, the chance and risk of developing malignant lesions are also unknown. In this study, no malignant lesions were observed during follow-up. In the future, if we can obtain more information on the abovementioned aspects, we will decide the goal of CP treatment and the follow-up strategy
There are some limitations in this study. First, due to the rarity of CP, it was very difficult to conduct a prospective, large sample-sized study, so we only retrospectively reviewed the clinical data of these patients, and because of the real world setting and the retrospective nature of the study, the treatment options were not chosen following a preestablished algorithm, and the pre-treatment conditions was hard to evaluate in different groups. Second, as no standard therapy for CP is recommended, the treatments varied greatly in different patients, and even in the same patients but in different periods; moreover, sometimes combined treatments were used. It was very difficult to simply generalize these therapies into several kinds and evaluate their efficacy. Third, as not all patients received colonoscopy during follow-up, in this study, recurrence was defined as polyps recurred in endoscopy or digital rectal examination, or symptoms appeared again. However, in some patients, they might have no symptoms, but colonoscopy would show polyp recurrence. If we defined recurrence as polyps recurred in endoscopy, then the recurrence rates in this study were underestimated. [26]
In conclusion, CP is a disease with an increasing incidence rate that is affecting mostly young males and it easily recurs. Endoscopic and imaging features can mimic IBD or rectal cancer, and their relationship with MPS is still under debate. The clinical improvement of medical treatments was not satisfactory and was inconsistent. Endotherapy or surgical resection could remove the polyposis and provide temporary relief, but the recurrence rates were high, with no difference between the two methods.