Perito, Emily R.*; Mileti, Elizabeth*; Dalal, Deepal H.*; Cho, Soo-Jin†; Ferrell, Linda D.†; McCracken, Marjorie*; Heyman, Melvin B.*
Solitary rectal ulcer syndrome (SRUS) is a rare condition most commonly characterized by rectal pain and bleeding. It can be accompanied by diarrhea or constipation, tenesmus, and rectal prolapse (1,2). Given its nonspecific symptoms, it is often difficult to diagnose, particularly in children. The incidence of SRUS has been estimated at 1 in 100,000 adults, with only a few reported pediatric cases (1,3). In the largest case series of children to date, 12 of 256 (5%) Iranian children with rectal bleeding and straining at the time of defecation were diagnosed with SRUS (3). Given that the histologic and endoscopic appearance mimics other disorders of the rectum, diagnosis of SRUS can be difficult (1,4).
We describe the range of presenting symptoms and endoscopic and histologic findings that should raise a clinician's awareness for pediatric patients warranting further assessment for SRUS.
All of the pediatric patients diagnosed with SRUS at the University of California, San Francisco Benioff Children's Hospital and an affiliated practice, Pediatric Gastroenterology Associates, were retrospectively reviewed. Cases were identified by searching medical records for International Classification of Diseases-9 code 569.41 and the Department of Pathology's biopsy database using “solitary (rectal) ulcer” and “mucosal prolapse” as search terms. Children younger than 21 years at diagnosis with biopsy-proven cases of SRUS between 1997 and 2009 were included.
All of the slides (hematoxylin and eosin) were reviewed by a pathologist (S.J.C.) to confirm the SRUS diagnosis. SRUS was defined by characteristic changes on rectal biopsy including smooth muscle hyperplasia in the lamina propria, hyperplasia of the muscularis mucosae, surface ulceration, architectural distortion (misshapen crypts), and ectasia of superficial capillaries. Patients whose biopsies were not confirmed as SRUS were excluded. Clinical records were then reviewed to identify presenting symptoms, endoscopic findings, laboratory values, treatments, and outcomes. Given the small number of patients in our series, we presented all of the descriptive statistics as median and interquartile range (IQR).
Fifteen pediatric patients from our database were diagnosed between 1997 and 2009 as having SRUS. Twelve were boys, and 9 (60%) were white. Median age at diagnosis was 13.9 (IQR 9.8–15.6) years (Table 1).
Common presenting symptoms included rectal bleeding, alternating diarrhea and constipation, abdominal pain, and perianal pain with defecation (Table 1). Nine of 15 (60%) complained of cramping abdominal pain, 9 (60%) had diarrhea, and 11 (73%) had blood in stool. Median duration of symptoms before diagnosis was 3.2 (IQR 1.2–5.5) years. Two patients (13%) were diagnosed with inflammatory bowel disease (IBD) before diagnosis with SRUS.
Laboratory data were collected from the time of initial visit to the University of California San Francisco Benioff Children's Hospital. Despite rectal bleeding in 73% of the patients, none were anemic. Median hemoglobin value was 13.1 (IQR 12.6–14.0) g/dL. All 9 patients with measured serum albumin levels had normal values (4.2, IQR 4.0–4.5 g/dL). Erythrocyte sedimentation rate was normal (4.0, IQR 3.5–5 mm/hour) in all but 1 patient, whose erythrocyte sedimentation rate was 17 mm/hour. This patient was subsequently diagnosed as having human leukocyte antigen-B27 spondyloarthropathy, although endoscopy, colonoscopy, and abdominal imaging showed no evidence of IBD, and biopsies were consistent with SRUS.
Other Diagnoses and Family History
Of the 2 patients diagnosed as having IBD, 1 patient had ulcerative colitis (UC) in conjunction with a history of autoimmune thyroiditis and autoimmune hepatitis. The other patient had a long-standing history of UC before the SRUS diagnosis. Both patients first presented with gastrointestinal symptoms, including loose bloody stools and abdominal pain, between 7 and 8 years of age. Both were initially diagnosed as having IBD and then subsequently diagnosed as having SRUS (2.5 and 7 years after presentation, respectively). Both had histologic findings consistent with SRUS in the distal rectum in addition to more proximal inflammation.
None of the 15 patients had a family history of SRUS. Neither of the patients diagnosed with IBD had a family history of IBD, but 3 of the other patients with SRUS (20%) had a family history of IBD.
Endoscopic findings varied widely. All of the patients had endoscopic abnormalities in the distal rectum, mostly limited to within 10 cm of the anal verge (Fig. 1). Of the 10 patients with endoscopic reports available, 8 had visible erythema or inflammation. Four patients had polyps or polypoid lesions. Patient characteristics are detailed in Table 2.
TABLE 2-b Patient ch...Image Tools
All of the patients (5) had at least 1 rectal biopsy with histologic findings that were consistent with SRUS or mucosal prolapse (Table 3). Multiple biopsies were available for review for 6 patients, with histologic features of SRUS seen in multiple biopsies for 4 of these patients. Common histologic findings included muscularization of the lamina propria with strands or bundles of smooth muscle extending between crypts, thickening or hyperplasia of the muscularis mucosae, surface ulceration with inflammation, focal hyperplastic changes in the epithelium, misshapen crypts, and vascular ectasia/congestion, which have been described in previous reports of SRUS or mucosal prolapse (6–11) (Figs. 2 and 3).
A mixed inflammatory infiltrate was often seen in areas of ulceration, but cryptitis or crypt abscesses and chronic changes characteristic of IBD were not seen in most biopsies. In the 2 patients with a concurrent diagnosis of IBD, 1 had a single biopsy available for review, which showed features of SRUS without features of IBD. Five biopsies were available for review for the other patient with IBD, 1 of which showed features of SRUS without features of IBD, 1 of which showed features of an inflammatory polyp, and 2 of which showed overlapping features (particularly surface ulceration with granulation tissue and dense inflammation). In addition, although reactive epithelial atypia was seen in biopsies of 3 of the patients, none of the biopsies had definitive evidence of dysplasia or adenocarcinoma.
The 13 patients without IBD were treated with laxatives, stool softeners, and mesalamine suppositories or enemas. Four underwent polypectomy at diagnosis. One patient required proctectomy for recurrent symptomatic polyps. The 2 patients with IBD were treated with stool softeners, oral or rectal aminosalicylates, oral or rectal corticosteroids, and antibiotics throughout the course of their follow-up. Several of the patients were lost to follow-up after initial diagnosis and treatment, precluding assessment of their response to treatment. In those patients who did have long-term follow-up, 6 of 9 responded to treatment, but at least 50% had recurrent symptoms, particularly after medication adherence lapsed.
Our review of pediatric patients at our institution revealed 15 cases of SRUS during a 13-year period. Presenting symptoms were consistent but nonspecific. Delay in diagnosis was common, likely because of the nonspecific symptoms and rarity of SRUS in the pediatric population. Our cases had a median 3.2-year delay between symptom onset and diagnosis. This is similar to the delay in diagnosis seen in pediatric patients with IBD, who also often present with similar symptoms (12). Treatment led to clinical improvement in most patients, but symptoms often recurred with poor medication adherence.
Our series confirms that SRUS is a misnomer because not all lesions are solitary or ulcers. Previous reports support this characterization (4,13). SRUS has also been referred to as mucosal prolapse to avoid this confusion (11). Endoscopically, the distal rectal mucosa typically appears erythematous, and lesions can be ulcerative or polypoid (3,14). Differential diagnosis in children includes juvenile polyps, infections, IBD, sexual abuse, or rectal digitations. Because our case search strategy relied on cases confirmed by pathology, we were not able to include cases suspected to be SRUS that did not have pathologic confirmation or were diagnosed as other disorders on histology.
Given the lack of symptom specificity and endoscopic findings seen in our cases, this series supports the necessity for histologic diagnosis. The histologic changes are similar to those seen in adults. Characteristic findings include muscularization of the lamina propria, hyperplastic muscularis mucosa, and distortion of crypt architecture (10,11,15). SRUS is distinguished from IBD by scarring of the lamina propria with only a relatively mild inflammatory infiltrate, as well as the accompanying muscular hyperplasia (15). Our patients without coexistent IBD had findings limited to the distal rectum.
Two of our cases, however, illustrate that SRUS and IBD can coexist in children and adolescents. Previous case reports in the adult literature have also noted concurrent SRUS and IBD, particularly UC (5,16). Thus, a diagnosis of IBD should not preclude consideration of SRUS, because management may differ. For those with concurrent SRUS and IBD, stool softeners and/or anti-inflammatory enemas to treat the SRUS may be necessary even when systemic medications are used to treat the IBD.
Because SRUS and IBD can present with identical symptoms—and have similar endoscopic features—SRUS can also be misdiagnosed as IBD. Misdiagnosis is concerning because the oral or intravenous immunosuppressive medications used for UC are unlikely to be effective in SRUS. In addition, because patients with long-standing IBD colitis can develop malignant lesions in the colon, SRUS can be misdiagnosed as tumor (16). Thus, histologic confirmation of the diagnosis is important to guide management. IBD with rectal ulcers could also be mistaken for SRUS; in general, features of systemic disease, such as weight loss, extraintestinal manifestations of IBD, or elevated serum inflammatory markers, should not be present in isolated SRUS.
Although its etiology is unclear, SRUS has been linked to direct mucosal trauma, rectal dysmotility, and ischemia. Strained defecation in some patients may lead to direct ulceration of the mucosa. In others, the anterior rectal mucosa is forced into the anal canal, causing rectal prolapse and mucosal injury (4,15). Rectal prolapse and high intraabdominal pressures may contribute to vascular compression, leading to mucosal ischemia (1). Tenesmus and straining related to IBD colitis have been theorized as contributors to the development of SRUS in patients with both disorders.
SRUS is not considered to be invasive or progressive; however, it tends to be refractory (6), as the outcomes of our patients suggest. Common treatments include laxatives, stool softeners, and rectal aminosalicylates (1,2,17). Surgery has also occasionally been used with minimal long-term success because the lesions often recur if the straining and dysmotility continue. In our patients, stool softeners and mesalamine suppositories were most often used. The small number of patients and variable follow-up prevent us from drawing robust conclusions about treatment efficacy.
Our analysis was limited because of the relatively small sample size and missing data. Multicenter prospective cohort studies would help identify treatment methods and outcome of pediatric patients with SRUS.
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