Saturday, July 4, 2009

Neutropenic Colitis

13 Year old male patient with ALL with febrile neutropenia showing marke thickening of the ceacum and ascending colon (arrows) suggestive of neutropenic colitis.

Neutropenic colitis, also termed typhlitis or necrotizing enteropathy, is an infectious condition coincident with severe neutropenia. Neutropenic colitis occurs as a complication of acute leukemia, aplastic anemia, or cyclic neutropenia. The cecum is most commonly involved, but the remaining colon and distal ileum also may be affected. Typical clinical features of neutropenic colitis are fever, watery diarrhea, abdominal pain, and occasionally a palpable mass. Recovery is correlated with remission of the underlying disease and return of adequate numbers of functioning neutrophils. Laparotomy and bowel resection is best avoided, unless gross perforation has occurred.

Plain radiographic findings of neutropenic colitis typically consist of right lower abdominal mass density surrounded by paralytic ileus or, rarely, obstruction. These findings are nonspecific and may mimic appendicitis. Barium enema studies are characterized by a thick-walled, poorly distensible cecum with thumb printing and transverse ridging. However, contrast studies are often avoided during episodes of suspected neutropenic colitis because of the danger of perforation and sepsis. The value of sonography for diagnosing neutropenic colitis has not been established; sonography may demonstrate cecal wall thickening, but presence of a pericecal paralytic ileus might impair sonographic results in some instances.

On CT scan there will be diffuse concentric ceacal wall thickeningThe thickened cecum will be isodense to surrounding normal bowel or contained intramural low-density areas consistent with edema, hemorrhage or necrosis, or pneumatosis. A mild paralytic ileus is often associated with neutropenic colitis. Decrease in cecal wall thickening coincided with recovery from neutropenic colitis.

Differential diagnosis of cecal wall thickening associated with neutropenic colitis includes lymphomatous or leukemic intramural deposits and hemorrhage. Lymphomas and leukemia often occur simultaneously, and both diseases may involve the bowel wall. Intramural hemorrhage and lymphomatous or leukemic deposits present as focal eccentric rather than diffuse bowel wall thickening. An abscess related to appendicitis and neutropenic colitis may exhibit similar clinical presentation. Appendicitis is a rare and deadly complication of acute leukemia and has been linked to drug toxicity. On CT, a periappendiceal abscess usually appears as a low-density mass with sharp or irregular margin. An enhancing rim or intrinsic air bubbles may be observed. Cecal wall thickening, however, is not an expected CT finding in appendicitis.

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