Triad of Typhlitis
The classic triad of typhlitis consists of severe neutropenia, fever, and abdominal pain (typically right lower quadrant), with diarrhea frequently present as an additional gastrointestinal manifestation. 1, 2
Clinical Presentation
The triad manifests in a specific temporal pattern and clinical context:
Neutropenia: Severe neutropenia (typically <500 cells/mcL) is the foundational element, occurring 1-2 weeks after initiation of intensive myelosuppressive chemotherapy 1, 3
Fever: Present in 67-83% of cases, representing the inflammatory and often infectious nature of the condition 2, 3
Abdominal pain: Diffuse initially, then localizing to the right lower quadrant as cecal inflammation progresses; present in approximately 83% of patients 2, 3
Diarrhea: While not part of the traditional "triad," watery or bloody diarrhea occurs in the majority of cases and should be considered part of the gastrointestinal symptom complex 4, 3
Additional symptoms include nausea, vomiting, and abdominal distension 3.
Pathophysiology Context
Typhlitis follows chemotherapy-induced neutropenia and is characterized by inflammation localized to the cecal wall, likely caused by bacterial invasion through damaged mucosa. 3 The condition occurs most commonly in patients with hematologic malignancies (particularly acute myelogenous leukemia) undergoing high-dose chemotherapy, with an incidence of 4-12% among oncology patients on active chemotherapy 2, 5.
Diagnostic Confirmation
While the clinical triad raises suspicion, imaging confirmation is essential:
CT scan (gold standard): Bowel wall thickening >4 mm (transversal) or >30 mm (longitudinal) in the cecum and terminal ileum 1
Ultrasound: Bowel wall thickening >5 mm; mortality risk increases dramatically when thickness exceeds 10 mm (60% vs 4.2%) 1, 6
Critical Pitfall
The absence of one element of the triad does not exclude typhlitis. 2, 5 Clinical signs may be muted or absent in severely neutropenic patients, making imaging mandatory when typhlitis is suspected rather than waiting for the complete triad to manifest 6, 7. Fever may be absent in up to 33% of cases, and abdominal findings can be minimal despite catastrophic intra-abdominal pathology 2, 8.