Immune Compromise

Jonathan H. Chung, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

Nonspecific Interstitial Pneumonitis
Organizing Pneumonia
Tumor
- Lung Cancer (HIV), AIDS-related Lymphoma, Kaposi Sarcoma, Post-transplant Lymphoproliferative Disease

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Immune compromise: Congenital or acquired conditions, which adversely affect immune system
- Hematological malignancy, congenital immune deficiency, HIV
- Stem cell transplantation, chemotherapy, corticosteroids, splenectomy
Fever not always due to infection
- Infection, drug toxicity, pulmonary hemorrhage, transfusion reaction, pulmonary emboli

Helpful Clues for Common Diagnoses

Pneumonia
- Often nonspecific clinical findings; fever, cough, chest pain, dyspnea
- Different imaging findings for specific microbial agents
  - Nodular consolidation with ground-glass halo or cavitation: Invasive fungal pneumonia (especially in neutropenia)
  - Diffuse ground-glass opacity, ± interlobular septal thickening: PCP or viral pneumonia
  - Upper lung fibrocavitary consolidation and bronchiectasis: Mycobacterial pneumonia
- Follow-up to resolution helpful to exclude malignancy
Pulmonary Edema
- History of left-sided heart failure, mitral valvular disease, or fluid overload
- Central preponderant airspace opacities with superimposed interlobular septal thickening
  - Kerley A and B lines represent thickened interlobular septa
- Rapid resolution with diuretics, inotropic agents, etc.
- Bilateral pleural effusions
Pulmonary Hemorrhage
- Ground-glass opacities > consolidation; tendency to spare peripheral, apical, and costophrenic aspects of lungs
- Increased interlobular and intralobular septal thickening over 1-2 days as blood products clear through lymphatics
- Rapid resolution over course of days
Drug Toxicity
- Imaging appearance depends upon underlying histology
  - Diffuse alveolar damage, organizing pneumonia, NSIP, eosinophilic pneumonia, hemorrhage
  - Hypersensitivity pneumonitis (rarely)

Helpful Clues for Less Common Diagnoses

Pulmonary Emboli
- High relative risk of venous thrombosis in hematological malignancy
- Filling defect in pulmonary artery
- Subpleural and lower lung preponderant pulmonary infarct(s)
  - Infarcts resolve over months, shrink in size while retaining original shape
Septic Emboli
- Longstanding central venous catheters predispose to septic emboli
- Multiple peripheral, basilar-predominant cavitary nodules/focal consolidation
- Loculated empyema
- Feeding vessel sign: Vessel leads directly into center of nodule or mass

Helpful Clues for Rare Diagnoses

Nonspecific Interstitial Pneumonitis
- Lower lung or diffuse ground-glass opacities; ± subpleural sparing
- Extensive traction bronchiectasis
- Reticular opacities (mild)
- Honeycombing not predominant CT pattern
Organizing Pneumonia
- Bilateral basilar predominant peripheral or peribronchovascular consolidation and ground-glass opacity
  - May be migratory or wax and wane
- Atoll sign (a.k.a. reverse halo sign): Central ground-glass opacity surrounded by rim of consolidation
- Perilobular opacities: Poorly marginated opacities outlining secondary pulmonary lobule
- Linear band-like opacities superimposed on airspace opacities in setting of stem cell transplantation
Tumor
- Non-small cell lung cancer more common in HIV(+) patients
- Kaposi sarcoma: Peribronchovascular, flame-shaped consolidation in AIDS
  - Usually associated mucocutaneous lesions
- AIDS-related lymphoma: Extranodal disease common, multiple pulmonary nodules, mild lymphadenopathy
- Post-transplant lymphoproliferative disease: Most common in solid organ transplant, multiple nodules or consolidation and lymphadenopathy

Alternative Differential Approaches

Tags: EXPERTddx: Chest

Aug 8, 2016 | Posted by drzezo in CARDIOLOGY | Comments Off

Thoracic Key