Differential Diagnosis for a 37-year-old Kidney Transplant Recipient with Fever

Single Most Likely Diagnosis

• Chronic rejection or graft dysfunction: This is a common issue in transplant patients, especially if there's a history of non-adherence to immunosuppressive medication or previous episodes of rejection. Fever can be a sign of an underlying infection or inflammation affecting the graft.

Other Likely Diagnoses

• Infections (e.g., urinary tract infections, pneumonia): Given the patient's immunocompromised state due to immunosuppressive therapy, they are at an increased risk for various infections.
• CMV (Cytomegalovirus) infection: A common viral infection in immunocompromised patients, especially in the first few months after transplant, but can occur at any time, especially if the patient is not on prophylaxis or has a high viral load.
• BK virus nephropathy: A viral infection that can cause damage to the transplanted kidney, particularly in patients with high levels of immunosuppression.

Do Not Miss Diagnoses

• Post-transplant lymphoproliferative disorder (PTLD): Although less common, this is a potentially life-threatening condition that can occur in transplant patients due to their immunosuppressed state. Fever can be an early symptom.
• Sepsis: Given the patient's immunocompromised status, any infection can quickly escalate to sepsis, a life-threatening condition that requires immediate attention.
• Medication side effects or toxicity: Certain immunosuppressive drugs can have side effects that include fever. Recognizing these early can prevent unnecessary complications.

Rare Diagnoses

• Transplant renal artery stenosis: A rare condition that can cause graft dysfunction and potentially lead to fever due to associated hypertension or renal ischemia.
• Recurrence of the original disease: Depending on the reason for the initial kidney failure (e.g., certain types of glomerulonephritis), there's a possibility, albeit rare, of the disease recurring in the transplanted kidney, potentially presenting with fever among other symptoms.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, laboratory results, and potentially imaging studies to determine the underlying cause of the fever.