February 2002

I am pleased to introduce our guest columnist this month, John F. Pohl, MD, who is also our new pediatric gastroenterologist here at Scott & White. He received his undergraduate degree from TCU in 1991 and his medical degree from The University of Texas Medical Branch at Galveston in 1995. His pediatric residency was at Phoenix Children’s Hospital and gastroenterology fellowship at Children’s Hospital Medical Center, Cincinnati. To read a little more about Dr. Pohl or any of our other pediatric staff, please visit our Web site, www.sw.org, and go to “Find a physician,” then to Department of Pediatrics. As usual, please don’t hesitate to write me at jhbrien@aol.com for comments about this column. I’ll be happy to respond to any observations; good, bad, or in between. I am especially interested in hearing about my mistakes. — James H. Brien, DO

A 14-year old boy was seen in the pediatric infectious disease clinic after a referral was made for bloody diarrhea during and after foreign travel. The patient had been living and traveling in the United Arab Emirates (UAE) with his family during the past two months.

Soon after the patient arrived in the UAE, he began to experience crampy abdominal pain in the bilateral lower quadrants. He also developed diarrhea and tenesmus with blood and mucous in his stool. Despite a normal appetite, the patient had a documented weight loss of almost 14 kg (30 lb). The patient had also experienced low-grade fevers and malaise. No other family members had similar symptoms. The patient’s past medical history was significant only for attention-deficit/hyperactivity disorder, and his immunizations were up to date. Family history was noncontributory. He was on no medications and had no recent antibiotic exposure. Like many adolescent patients with problems like this, he kept this problem to himself, revealing it to his mother only after she questioned him about his weight loss.

Examination revealed a pale and thin male with a weight of 60 kg (130 lb). Vital signs revealed a temperature of 99° F, pulse of 106, respirations of 12, and a blood pressure of 110/60. A cardiac exam revealed sinus tachycardia with no murmur. The lungs were clear to auscultation. The abdominal exam revealed tenderness in both the left and right lower quadrants without rebound or guarding. An appreciable fullness was present in the right lower quadrant. A rectal exam revealed an anal tag with an underlying fistula (figure 1). The rest of his examination was normal. The stool was hemoccult positive for blood. A CBC showed a white blood cell count of 6,100/mm³, hemoglobin of 11.6 gm/dl, hematocrit of 36%, MCV of 72 fl (normal 80-94 fl), and platelets of 524,000/ml. The erythrocyte sedimentation rate was 51 mm/hr. Stool studies for pathogens were obtained. A computed tomography (CT) scan of the abdomen showed thickening of the rectosigmoid region (arrow) and distal ileum (figure 2). Colonoscopy revealed erythematous ulcers (arrows) throughout the mucosa (figure 3), and biopsies were obtained (figure 4 showing an H&E stain of tissue).

What's Your Diagnosis?

1. Escherichia coli infection
2. Entamoeba histolytica infection
3. Crohn’s disease
4. Behçet’s disease
5. Salmonella enteritidis infection

Answer

The answer is 3, Crohn’s disease. Dysentery, ie, bloody diarrhea, often is associated with both bacterial and parasitic infections. However, the physician should always remember noninfectious causes of bloody diarrhea and tenesmus. The presence of a rectal tag and fistula associated with diarrhea, blood in the stool, and weight loss points to the diagnosis being #3. Stool tests for bacterial pathogens, ova and parasites, and Clostridium difficile toxin were negative.

Bacterial causes of bloody diarrhea are numerous. In the older child, most cases of Salmonella enteritis cause fever, nausea and diarrhea that can be bloody. It is generally a self-limited infection, and antibiotics are not required unless the child is younger than 3 months of age. Campylobacter species can cause a self-limited bloody diarrhea and has also been associated with pancreatitis, Reiter’s syndrome and Guillain-Barré syndrome. Both enteroinvasive Escherichia coli (EIEC) and enterohemorrhagic E. coli (EHEC) can cause dysentery, and transmission is often from contaminated food and water. EHEC is associated with hemolytic uremic syndrome (HUS), and antibiotics have been associated with an increased risk of developing and/or worsening HUS.

Most parasitic infections are not associated with dysentery. The exception is Entamoeba histolytica that exists in both the motile trophozoite and cyst form. Acute amebic dysentery has a similar clinical presentation as bacterial dysentery and can progress to toxic megacolon and amebic liver abscess. Steroid therapy should not be initiated for potential inflammatory bowel disease (IBD) if Entamoeba infection is still being considered a possibility. Traveling in the UAE should not necessarily place him at increased risk of amoebic infection, but should be considered, as it should be for any patient with prolonged, bloody stools with weight loss.

It is extremely important to evaluate for the presence of a bacterial or parasitic infection before considering treatment for possible IBD. I always obtain stool specimens for bacterial culture as well as ova and parasite examination before starting immunomodulatory agents. I also check for C. difficile toxin as this pathogen has a significant comorbidity associated with IBD. The presence of a rectal tag with fistula (figure 1) virtually confirmed the diagnosis of IBD in this patient, although it was essential to perform endoscopy to differentiate between Crohn’s disease and ulcerative colitis.

IBD is a chronic inflammatory disease of the intestines with an unknown etiology although genetic, infectious and autoimmune factors probably all contribute to its pathology. Ulcerative colitis is a chronic inflammatory disease affecting only the colon and rectum. The inflammation of the colon is continuous, and biopsies of the colon reveal inflammation confined to the crypt region. Crohn’s disease, on the other hand, has a patchy inflammatory appearance (figure 3) affecting both the small and large intestine. Extraintestinal disease, such as apthous ulcerations of the mouth and perianal tags, fissure and fistulas are common. Biopsies of the intestine reveal patchy inflammation that invades the lamina propria. The presence of noncaseating granulomas in the biopsy are diagnostic of Crohn’s disease (figure 4). In this patient, upper endoscopy revealed a chronic gastritis while biopsies from the colonoscopy revealed a patchy active colitis with granuloma formation. Other autoimmune conditions affecting the intestine should be considered during the evaluation for IBD.

Behçet’s disease, a multisystem vasculitic disorder, is characterized by apthous stomatitis, genital ulcers, uveitis and intestinal ulcers (often in the ileocecal region). Arthritis, skin lesions, neurologic involvement, and a tendency for prothrombtic complications also have been described. It has an increased incidence in young adults in Japan, the Mediterranean region, and the Middle East. Behçet’s disease is rare, and diagnosis usually is made after a good clinical exam.

Treatment of IBD has progressed over the past 40 years to the use of more immune-specific agents. Aminosalicylates (sulfasalazine, mesalamine, etc.) were one of the first immune-modulating agents used in treatment of IBD and have an inhibitory effect on leukotriene synthesis. Glucocorticoids are the mainstay of therapy for acute exacerbations of inflammation due to their wide range of anti-inflammatory and immunosuppressant effects. However, long-term usage is limited by steroid side effects including adrenal suppression, diabetes, hypertension, cataract formation, delayed wound healing and osteoporosis.

Antibiotic therapy, specifically metronidazole and ciprofloxacin (Cipro, Bayer), have been shown to be effective for the perianal complications of IBD via antibiotic and immunomodulatory mechanisms. Newer immunosuppressant therapy such as 6-mercaptopurine, an antagonist for purine metabolism, and infliximab (Remicade, Centocor), an anti-TNF (tumor necrosis factor) monoclonal antibody, have found increased usage for the treatment of pediatric inflammatory bowel disease. This patient has responded well to high-dose prednisone as well as mesalamine, metronidazole and ciprofloxacin.

Obviously, the presentation of diarrhea and blood in the stool should have a clinician consider both infectious and noninfectious diseases. The rectal exam is an integral part of the exam for every child who presents with any type of gastrointestinal symptom (abdominal pain, constipation, diarrhea, blood in stool, etc.). Medical students and residents often ask me when a rectal exam should be deferred in the pediatric setting. I give them the two contraindications that I was taught during fellowship training: #1. No finger, #2. No rectum. It is evident that the rectal exam is an extremely underused, yet valuable aspect, of the pediatric physical exam.

Finally, it is imperative to make sure that a patient does not have an underlying bacterial or parasitic infection before starting steroids so that complications such as sepsis and toxic megacolon can be prevented.

For Your Information:

• James H. Brien, DO, Pediatric Infectious Disease, Scott and White's Children's Health Center and Texas A&M University, College of Medicine, Temple, Texas. E-mail: jhbriend@aol.com