Clinical History
A 40 year old woman with acute myeloid leukaemia (AML) was evaluated for neutropenic fever, malaise and abdominal pain.
Imaging Findings
A 40 year old woman with AML was admitted with severe neutropenia, fever, malaise and abdominal pain after the last cycle of chemotherapy. Abdominal CT scan revealed diffuse thickening (ranging 4-20 mm) of the intestinal wall, from the last ileal loop to the transverse colon. The thickened cecum was isodense to normal gut with intramural areas of lower density, and it was surrounded by adipose tissue oedema and severe ascites.
Ileum adjacent to the abnormal cecum was slightly distended (mild paralytic ileus) with no signs of intestinal perforation. Typical clinical features and CT findings suggested the presence of neutropenic colitis. Laparotomy was promptly performed, revealing an indurated and thickened cecum. There were no perforation signs, but resection was performed.
Discussion
Neutropenic colitis, also termed typhlitis or necrotizing enteropathy, is an infectious condition coincident with severe neutropenia. It occurs as a complication of acute leukemia, aplastic anaemia, or cyclic neutropenia and it is characterized by intramural bacterial invasion without an inflammatory reaction. Bacteria, viruses, and fungi penetrating the damaged cecal mucosa grow profusely in the absence of neutrophils. This leads to oedematous thickening and induration of the cecal wall or other segments of the colon and distal small bowel, which often results in septicemia and death. The cecum is most commonly involved, because it represents an area of relative stasis of bowel content and is easily distensible.
Mucosal ulcerations and perforations create a mural port of entry for the resident microflora and occur with ischemia, which may be associated with distension alone or aggravated by intramural haemorrhage. Typical clinical features of neutropenic colitis are fever, watery diarrhoea, abdominal pain, and occasionally a palpable mass.
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. Pneumatosis of the cecum also has been described in neutropenic colitis and carries a poor prognosis.
Contrast studies are often avoided during episodes of suspected neutropenic colitis because of the danger of perforation and sepsis. Sonography may demonstrate cecal wall thickening, but the presence of a pericecal paralytic ileus might impair sonographic results in some instances.
CT scans show diffuse cecal wall thickening in all patients with neutropenic colitis (wall thickness greater than 4 mm in a distended bowel segment is considered abnormal). As in our case, the thickened cecum may be isodense to surrounding normal bowel or contain intramural low-density areas consistent with oedema, haemorrhage or necrosis, or pneumatosis. A mild paralytic ileus is often associated with neutropenic colitis. These findings suggest neutropenic colitis in patients with fever, abdominal pain, neutropenia, and either acute leukaemia, aplastic anaemia, or cyclic neutropenia.
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.
Differential Diagnosis List
