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Inflammatory cap polyposis (CP) is an uncommon, non-malignant condition whose pathogenesis is poorly understood. Initial presentation of CP may mimic other gastrointestinal conditions like inflammatory bowel disease, pseudomembranous colitis, irritable bowel syndrome, and colon cancer.
A 42-year-old male presented with symptoms of constipation, abdominal pain and weight loss, which were suggestive of a malignancy.
Since the symptoms of CP resemble closely those of other gastrointestinal diseases, particularly colon cancer, making the initial diagnosis can be challenging and it is often delayed. The mainstay of initial treatment is conservative, however symptomatic and complicated cases require prompt surgical intervention with close clinical follow-up.
We chose to report this case because it represents a rare and unique disease process that may masquerade as a colon cancer. It is important for surgeons to be aware of this non-malignant condition since inadequate surgery usually results in recurrence.
Inflammatory cap polyposis (CP) is a rare, non-malignant condition characterized by the presence of sessile and pedunculated polyps in the colon and rectum. The histology of these polyps reveals a “cap” of inflammatory granulation tissue with fibrinopurulent exudate that covers the polyps, hence the name “inflammatory cap polyposis”. The pathogenesis of this non-malignant condition is poorly understood and while several associations have been made, causality has yet to be elucidated. The mainstay of initial treatment is conservative, however complicated and refractory cases usually benefit from prompt surgical intervention followed by close surveillance for disease recurrence and progression. Our surgical team encountered a case of CP when a patient presented with symptoms suggestive of an ongoing malignancy but whose pathology confirmed a non-malignant process with complicated symptoms of obstruction.
A 42-year-old male with a past medical history significant for HIV, perianal condylomata, irritable bowel syndrome, H. pylori gastritis, and hyperlipidemia with a negative past surgical history presented to the Infectious Disease clinic where he had been followed for his HIV with a several month history of worsening constipation, abdominal pain, and a 20-pound weight loss. He was sent for colonoscopy which revealed a circumferential polypoid lesion within the sigmoid colon, biopsies of which only showed inflammation and no malignancy. CT scan of the abdomen demonstrated colonic and small bowel distension proximal to the patient's known colon obstruction without any evidence of metastatic disease (Fig. 1a and b). He was referred to the Surgical Oncology clinic for a presumed sigmoid cancer where he presented in moderate discomfort with persistent abdominal pain, constipation, and feculent vomiting. His physical examination was notable for a non-rigid abdomen with slight abdominal distension and tenderness to deep palpation diffusely. On laboratory testing, his complete blood count and serum chemistries were within normal reference ranges and his CD4 count was 617 (normal = 400–1600) with an undetectable viral load. The patient was promptly admitted, and taken urgently to the operating room for a sigmoid resection and colostomy (Hartmann's Procedure). Surgical pathology revealed serosal thickening with hyperemia, multiple areas of mucosal ulceration, and multiple polyps covered with caps of granulation tissue that were consistent with a diagnosis of cap polyposis (Fig. 2a). Histology of the cap polyposis showed thickened, hyperemic serosal, ulceration of the mucosa, and hallmark polyps with granulation tissue caps (Fig. 2b). No neoplasm was found in the surgical specimen. Postoperatively, he was followed quarterly and continued to do well, but was noted to have numerous new polyps on his stoma. Surveillance colonoscopy at one-year post-surgery in preparation for stoma closure revealed progression of disease in his transverse and descending colon as well as in his rectal remnant. Based on the presence of this extensive disease, the patient elected to undergo a proctocolectomy and have an ileostomy as opposed to an ileoanal j-pouch reconstruction. He continues to do well and has had no further GI symptoms ten months after surgery.
Inflammatory cap polyposis is an uncommon, non-malignant condition of the colon and rectum that was first described by Williams and colleagues in 1985.1 Symptoms of cap polyposis include bloody mucoid diarrhea, abdominal pain, constipation, and weight loss, all of which can mimic other gastrointestinal conditions like inflammatory bowel disease, pseudomembranous colitis, irritable bowel syndrome, and colon cancer.2,3 The most frequently reported presenting features of CP are rectal bleeding, constipation, straining with defecation, and mucoid diarrhea.4 The pathologic features of cap polyposis include both sessile and pedunculated polyps with erythema and inflammation that tend to occur in the sigmoid colon or rectum, but may occupy the entirety of the colon.5,6 These polyps generally occur at the apices of transverse mucosal folds.1,3 The histology of cap polyposis reveals a “cap” of inflammatory granulation tissue with fibrinopurulent exudate that covers the polyps, as well as an infiltrate of mixed inflammatory cells within the lamina propria, and elongated serpiginous crypts in the polyps themselves.3,7,8 This condition occurs primarily during the fifth decade and has more often been described in women than men. However, case reports have shown cap polyposis in both women and men anywhere from age 12 to 76 years with a median reported age of 52 years.1,9,10 The pathogenesis of cap polyposis is poorly understood. Suggestions of its etiology have included chronic H. pylori infection based on some improvement with antibiotic treatment, previous pelvic surgery, and mucosal trauma from repeated straining with constipation.4,9,11 Additionally, comparable symptoms as well as histological similarities exist in both cap polyposis and mucosal prolapsed syndrome leading to the possible association between the two. Also described is the association of cap polyposis and colonic motility abnormalities, though causality has yet to be identified.12–14
Currently, there are no reports that cap polyposis has malignant potential. The natural history of this condition typically includes the formation of a single pedunculated colonic polyp that then leads to polyp formation proximally within the colon as well as in and around previous surgical anastomotic lines.5,13,15 Diagnosis is based upon the history of the most common features of the condition as well as colonoscopy with biopsies and histological examination.1,4,5,8 Colonoscopy typically shows erythematous polyps with an adherent mucoid cap. Magnification and chromographic endoscopy can be done to demonstrate the mixture of round crypts in the depressed cluster with long branching crypts in the surrounding elevated areas, which may help it differentiate from other inflammatory conditions.8 The mainstay of initial treatment is conservative measures including avoidance of straining with constipation, H. pylori eradication, as well as medical treatment with immunosuppressive agents and metronidazole.4,6,7,10,14,16 Steroids and infliximab are some of the immunosuppressive agents used to treat cap polyposis. However, there are reports of relapse even after 15 years of remission while being on steroid therapy.17 Similarly there are reports which have shown failure to infliximab treatment, thus the role of steroids and infliximab in treating cap polyposis is not well established.18 Because of this patient's HIV status, immunosuppression therapy was not initiated. In addition to medical treatment, symptom-alleviating polypectomy should be performed.1,4 Repeat colonoscopies as well as close clinical follow-up should be conducted in order to monitor for disease persistence or progression. Surgical intervention including partial or total colectomy should be done in medically refractory cases or in these patients who recur, such as our patient.1,4,5 Several reports have suggested that cap polyposis will commonly recur with inadequate surgery (i.e. partial colectomy), so repeat operations including total colectomy are indicated in these cases.3,4,11
Initial symptoms of cap polyposis are very similar to those of other gastrointestinal diseases, thus the diagnosis can be challenging and delayed. Surgeons should be aware of this non-malignant condition as it may need symptom-alleviating polypectomy or a full colectomy in more refractory cases. Close clinical follow-up and colonoscopies should be done to monitor disease progression and recurrence as inadequate surgery commonly results in recurrence.
Written informed consent has been obtained by the patient.
Meredith Mason is the 1st author, Syed Adeel Faizi, Edgar Fischer and Ashwani Rajput are co-authors.
Conception and design: Ashwani Rajput.
Collection and assembly of data: Meredith Mason, Syed Adeel Faizi, Edgar Fischer.
Data analysis and interpretation: Meredith Mason, Syed Adeel Faizi, Ashwani Rajput.
Manuscript writing: All authors.