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Figure 1. Ultrasound of right lower quadrant demonstrated hypoechoic mucosal thickening and polypoid appearance (black arrows) of the cecal mucosa.
Figure 2. Same ultrasound of right lower quadrant (more inferiorly) showed the appendix with 2 echogenic round appendicoliths (black arrows) producing posterior acoustical shadowing.
Figure 3. Computed tomographic scan at the same anatomical location of Figure 1 ultrasound showed thickening of the wall and mucosa of cecum (black arrows).
Figure 4. Computed tomographic scan at the same anatomical location of Figure 2 ultrasound demonstrated thick cecum (open white arrow) and appendix, with 2 hyperdense appendicoliths (black arrows) within the appendix.
The patient was given clindamycin hydrochloride as antibiotic coverage for the presumed diagnosis. The patient was also given pain control medication. Transfusions continued, with rising hematocrit level and platelet count, but there was persistent pancytopenia. Right lower quadrant guarding and tenderness subsided over 1 week, and the patient was discharged home.
Typhlitis is a necrotizing inflammation of the colon and ileum in neutropenic patients. The cecum (typhlon in Greek) is the region most frequently involved. It occurs in patients with leukemia but may also develop in patients with lymphoma, aplastic anemia, cyclic neutropenia, and acquired immunodeficiency syndrome or after organ transplantation. The cause is bacterial invasion of the colonic wall, compromised by chemotherapy. Cytomegalovirus and Mycobacterium tuberculosis are the pathogens isolated most commonly.1 The most frequent symptoms include fever, abdominal pain, and distention.2 Typhlitis, appendicitis, intussusception, perforation, and intestinal obstruction all may present with symptoms in the right lower quadrant, leaving the surgeon with a diagnostic dilemma.3 The treatment for typhlitis is usually supportive using antibiotics, and surgery is reserved for secondary perforation and peritonitis.2
Radiographic findings of typhlitis may include a paucity of bowel gas in the right lower quadrant, small bowel ileus, ascites, and mechanical obstruction. The prominent mucosal thickening and polypoid appearance of the mucosa make the ultrasonographic picture of typhlitis different from other diseases affecting the cecal area, such as granulomatous colitis, appendicitis, and intussusception. Typically, the edema and thickening of the bowel wall in these conditions is hypoechoic as opposed to the echogenic thickening in typhlitis.3,4 Computed tomography of typhlitis has shown thickening of the bowel wall and mucosa of the cecum and ascending colon.
With ultrasonography, the normal appendix is compressible, with a wall less than 3-mm thick. Ultrasound visualization of the appendix with a total diameter greater than 6 mm in a patient with right lower quadrant pain is highly suggestive of acute appendicitis. Visualization of an appendicolith, regardless of appendiceal diameter, should also be regarded as a positive finding.1 Compared with ultrasound, similar sensitivities and specificities have been shown with prospective studies using CT to diagnose appendicitis in children. A normal appendix can be seen in 50% of healthy children on CT examinations. It appears as a tubular structure, with a thin wall surrounded by homogeneous low-attenuation fat. Findings from CT of appendicitis can be classified as primary or secondary. Primary signs are pathognomonic and include either visualization of an inflamed appendix or appendicolith associated with inflammatory changes. Secondary signs are suggestive but not diagnostic and can be seen with other inflammatory processes such as Crohn disease and pelvic inflammatory disease. These include inflammatory changes or abscess in the right lower quadrant or pelvis without visualization of an abnormal appendix or appendicolith.5
Accepted for publication November 30, 1998.
Reprints: Sarah G. Klein, MD, Department of Radiology, Arkansas Children's Hospital, 800 Marshall St, Slot 700, Little Rock, AR 72202 (e-mail: KleinSarahG@exchange.uams.edu).
Radiological Case of the Month. Arch Pediatr Adolesc Med. 2000;154(6):630. doi: