Differential Diagnosis for Tree-in-Bud Nodularity on CT Scan

Given the patient's symptoms of new onset chills, cough, unintentional weight loss, acute kidney injury (AKI), and recent exposure to moldy corn, along with the finding of tree-in-bud nodularity on a CT scan, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Invasive Aspergillosis: This is a fungal infection caused by Aspergillus species, which the patient may have been exposed to through moldy corn. The symptoms and imaging findings, including tree-in-bud nodularity which represents bronchiolar dilatation and filling with secretions or debris, are consistent with this diagnosis. Invasive aspergillosis can lead to severe pulmonary disease and is known to cause AKI, either directly or through the use of nephrotoxic antifungal medications.

• Other Likely Diagnoses

  • Bronchiolitis Obliterans: This condition could present with similar symptoms and imaging findings, especially in the context of an infectious or toxic exposure. However, it typically follows a more subacute or chronic course.
  • Mycobacterial Infection: Such as tuberculosis or non-tuberculous mycobacterial (NTM) infection, can cause tree-in-bud nodularity on CT scans. These infections can also lead to systemic symptoms like weight loss and cough.
  • Cryptogenic Organizing Pneumonia (COP): While less likely given the exposure history, COP can present with similar radiographic findings and systemic symptoms.

• Do Not Miss Diagnoses

  • Histoplasmosis: Another fungal infection that could be acquired through exposure to contaminated soil or organic matter. It can cause severe pulmonary and systemic disease, including AKI, and has a similar geographic distribution to areas where moldy corn might be found.
  • Blastomycosis: A fungal infection that can cause pulmonary disease with similar symptoms and imaging findings. It is also associated with exposure to soil and organic matter.
  • SARS-CoV-2 or Other Viral Pneumonias: Although less likely given the specific exposure to moldy corn, viral pneumonias can cause a wide range of pulmonary and systemic symptoms, including AKI, especially in severe cases.

• Rare Diagnoses

  • Hypersensitivity Pneumonitis: An immune-mediated lung disease caused by inhalation of various antigens, including moldy organic dusts. It could present with similar symptoms and radiographic findings, although the clinical context and exposure history would be key to distinguishing it from other diagnoses.
  • Idiopathic Tree-in-Bud Pattern: A rare condition where the tree-in-bud pattern on CT scan is not associated with any identifiable cause, presenting a diagnostic challenge.