Typhlitis

Typhlitis, also known as neutropenic colitis, is a necrotising inflammatory condition which typically originates in the caecum and, often extends into the ascending colon, appendix or terminal ileum, by the time of presentation. In general patients are immunocompromised, usually neutropenic.

Terminology

With regards to nosology, typhlitis is an unusual term, in that it refers to an inflammation of part of the body restricted to those cases which are neutropenic, or rarely non-neutropenic immunocompromise ¹⁵. In general, inflammation of the caecum or caecitis, in the non-immunocompromised patient is not called typhlitis. Other synonyms used for typhlitis include neutropenic caecitis, neutropenic enterocolitis, neutropenic enterocecitis and typhlenteritis ^14,15.

Epidemiology

Typhlitis was first described in children with leukaemia and severe neutropenia (seen with an absolute neutrophil count <1000 per microlitre). It most commonly occurs in immunocompromised patients, chemotherapy and steroid therapy patients including:

• leukaemia (most common)

• lymphoma

• aplastic anaemia

• AIDS

• solid organ transplant

Clinical presentation

Clinically, patients with typhlitis present with a mixture of localised and systemic symptoms including a fever, chills, nausea, vomiting, diarrhoea, abdominal pain, tenderness and a distended abdomen. Peritoneal irritation and occult bloody stools may be present. Pain in the right lower quadrant may mimic appendicitis.

Pathology

The condition is characterised by intramural bacterial invasion without an inflammatory reaction in the context of immunosuppression. This then leads to oedematous thickening and induration of the caecal wall or other mural segments of the colon and distal small bowel.

The exact cause is unknown but is believed due to be a combination of ischaemia, infection (especially with cytomegalovirus, Pseudomonas aeruginosa), mucosal haemorrhage, and perhaps neoplastic infiltration ¹.

Radiographic features

Plain radiograph

Plain film findings are often non-specific. May show evidence of a small bowel obstruction (SBO), soft-tissue mass in the right lower quadrant, thumbprinting due to bowel wall oedema, intramural gas and/or bowel wall thickening.

Ultrasound

Transabdominal ultrasonography demonstrating bowel wall thickening in an appropriate clinical context has been used to supplement the clinical diagnosis of typhlitis. Bowel wall thickening may be eccentric or concentric and is often dramatic; caecal wall measurements are often above 1 cm in severe cases. Sonographic findings are relatively non-specific, but are especially helpful in high pretest probability patients, and may also address the possibility of cholecystitis which, especially in the immunocompromised, has an atypical presentation ¹³. 

Bowel wall thickening >4 mm is virtually always demonstrated; other features consistent with the diagnosis include:

• preferential involvement of terminal ileum, caecum, and ascending colon

  • involved segments often demonstrate luminal distension with hypoechoic fluid

  • increased echogenicity of pericaecal fat

• localised hypokinesis/akinesis of involved bowel loops, with otherwise preserved motility

• hypoechogenicity of the thickened bowel wall

  • haustral folds in involved colonic segments are usually preserved

  • colour flow interrogation of involved bowel demonstrates preservation of bowel wall perfusion

  • characteristic echogenic thickening of the mucosa has been reported in some paediatric reports ⁸

Computed tomography should always supplement sonographic evaluation of typhlitis, especially for occult complications including intra-abdominal abscess and bowel perforation.

CT

This is often the imaging modality of choice in patients suspected of having typhlitis in view of high risks of perforation during optical colonoscopy or during a barium enema ⁵.

CT may demonstrate thickening of the caecum as well as fat stranding, pneumatosis intestinalis, bowel wall thickening and ileus. Features of small bowel obstruction may also be seen. There may be intramural areas of low attenuation which may represent haemorrhage or oedema ⁴. 

Serial CT may also play a role in monitoring the success of treatment ⁵. 

Angiography (DSA)

Arteriography is not part of the routine assessment. The entire caecum may be hypervascular, which may be seen as intense staining of the mucosa and its folds ².

Treatment and prognosis

If possible, management should be conservative with IV antibiotics, nasogastric suctioning, and bowel rest. Any delay in diagnosis may result in transmural bowel necrosis. Surgical resection may be necessary for bleeding or bowel infarction.

Differential diagnosis

For terminal ileitis consider the differential diagnosis of a terminal ileitis.

If a patient is not immunocompromised, then it is usually worth considering an alternative diagnosis, as a few case reports aside, typhlitis is not usually considered to be an entity in the immunocompetent ¹⁶.

History and etymology

Refers to "typhlós", ancient Greek word for "blind" (referring to the blind-ending caecum) ¹².