What type of patients are at risk of developing typhlitis, particularly those with compromised immune systems due to conditions such as cancer, Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS), or immunosuppressive therapy?

Patient Populations at Risk for Typhlitis

Typhlitis (neutropenic enterocolitis) occurs predominantly in patients with severe neutropenia following chemotherapy for hematologic malignancies, particularly acute myelogenous leukemia, though it can also develop in other immunocompromised states including solid organ transplant recipients, HIV/AIDS patients, and those on immunosuppressive medications. 1

Primary High-Risk Populations

Cancer Patients on Chemotherapy

• Acute myelogenous leukemia patients represent the highest risk group, especially those receiving high-dose cytosine arabinoside (Ara-C) chemotherapy 2, 3
• Typhlitis typically develops 1-2 weeks after chemotherapy initiation, during the period of maximal mucosal damage and neutropenia 1
• Approximately 6.5% of neutropenic patients undergoing myelosuppressive therapy develop neutropenic enterocolitis 1
• The real incidence ranges from 0.8% to 26% across cancer populations 1
• Patients with non-Hodgkin lymphoma and other hematologic malignancies are also at significant risk 3
• Solid organ cancer patients receiving high-dose chemotherapy can develop typhlitis 1

Transplant Recipients

• Solid organ transplant patients, particularly kidney transplant recipients, are at risk due to chronic immunosuppression with medications like prednisone and cyclosporine 3
• These patients have moderate to severe immunocompromise that predisposes to neutropenic enterocolitis 1

HIV/AIDS Patients

• Patients with HIV who have progressed to AIDS represent an acquired immunodeficiency state that increases typhlitis risk 1, 3
• The combination of HIV-related immunosuppression and potential concurrent medications creates vulnerability 1

Other Immunosuppressive Conditions

• Patients with aplastic anemia are at risk due to baseline neutropenia 3
• Patients on immunosuppressive therapy for rheumatologic conditions (e.g., sulfasalazine for psoriatic arthritis) can rarely develop typhlitis 4
• Patients with common variable immunodeficiency have documented cases 5

Critical Risk Factors and Timing

Neutropenia Characteristics

• Severe neutropenia is the hallmark risk factor, with typhlitis occurring during the nadir of white blood cell counts following chemotherapy 1, 2
• The condition typically manifests during the second to third week after chemotherapy initiation 1
• Resolution directly correlates with recovery of neutrophil counts 1, 2

Medication-Related Risk

• Specific chemotherapy agents carry higher risk: cytosine arabinoside (Ara-C), vincristine 3
• Chronic corticosteroid therapy increases risk 1, 3
• Cyclosporine and other immunomodulatory drugs for transplant or autoimmune conditions 3

Important Clinical Context

Severity Stratification

• Patients with bowel wall thickening >10mm on CT imaging have a 60% mortality risk, indicating advanced disease 1, 6
• Mortality in patients with radiologic signs of neutropenic enteritis reaches 29.5% even with appropriate treatment 1

Rare Presentations

• While typhlitis has been described in a non-immunocompromised elderly patient, this represents an exceptional case 7
• The overwhelming majority of cases occur in clearly immunocompromised hosts 1, 2
• Clinicians should maintain high suspicion primarily in neutropenic and immunosuppressed populations, though elderly patients with atypical presentations warrant consideration 7

Common Pitfall

• Do not dismiss the diagnosis in patients whose absolute neutrophil count appears elevated if they are in the recovery phase post-chemotherapy, as relative leukocytosis can occur during neutrophil recovery while mucosal damage persists 8
• The diagnosis requires combining clinical presentation (fever, right lower quadrant pain, diarrhea) with imaging findings (cecal wall thickening >5mm) and patient history of recent chemotherapy or immunosuppression 1, 2