Differential Diagnosis for Nephrostomy Site Infection in a Patient on Chemotherapy

Single Most Likely Diagnosis

• Urinary Tract Infection (UTI) or Pyelonephritis: The presence of a nephrostomy tube increases the risk of introducing bacteria into the urinary tract, leading to infection. The symptoms of a raw area underneath the nephrostomy site with possible pus are consistent with a localized infection. Chemotherapy can suppress the immune system, making the patient more susceptible to infections.

Other Likely Diagnoses

• Exit Site Infection: This is a common complication of nephrostomy tubes, where the skin around the exit site of the tube becomes infected. Symptoms include redness, swelling, and pus at the site.
• Tunnel Infection: Similar to an exit site infection but occurs along the subcutaneous tract of the nephrostomy tube. It presents with signs of infection along the tunnel.
• Fungal Infection: Patients on chemotherapy are at an increased risk of fungal infections due to immunosuppression. Candida species are common pathogens in such cases, and the infection can manifest similarly to bacterial infections.

Do Not Miss Diagnoses

• Sepsis: Although less likely as a primary diagnosis, any infection in an immunocompromised patient can quickly escalate to sepsis, a life-threatening condition. Early recognition and treatment are crucial.
• Necrotizing Fasciitis: A rare but deadly infection of the skin and subcutaneous tissue. It requires immediate surgical intervention and can be masked by the presence of a nephrostomy tube, making it a "do not miss" diagnosis.

Rare Diagnoses

• Mycobacterial Infection: Infections caused by Mycobacterium species (e.g., tuberculosis) can occur in immunocompromised patients and may present with chronic or atypical symptoms.
• Atypical Bacterial Infections: Certain bacteria that are less common causes of infection, such as Pseudomonas or Enterobacter species, might be considered, especially if the patient has been exposed to broad-spectrum antibiotics.

Management and Treatment

Treatment will depend on the specific diagnosis but generally includes:

• Antibiotics: For bacterial infections, guided by culture and sensitivity results.
• Antifungals: For fungal infections.
• Supportive Care: Wound care, pain management, and monitoring for signs of sepsis or other complications.
• Surgical Intervention: May be necessary for tunnel infections, necrotizing fasciitis, or in cases where the infection does not respond to medical management.
• Removal or Replacement of Nephrostomy Tube: If the tube is the source of infection and cannot be salvaged with antibiotics.