Centrilobular Lung Nodules

• bronchiolitis
• endobronchial spread of TB, MAC
• bronchopenumonia
• hypersensitivity pneumonitis
• endobronchial spread of tumor
• pneumoconiosis
• organizing pneumonia (BOOP)
• histiocytosis
• edema or vasculitis

Random Lung Nodules

• miliary TB
• miliary fungal infections
• hematogenous mets
• sarcoidosis

Perilymphatic Lung Nodules

• sarcoid
• lymphangitic spread of tumor
• silicosis and CWP
• amyloid
• LIP

AIDS Chest Differential

Focal Lung Disease

• Bacterial pneumonia
• PCP
• Mycobacterial/fungal infection
• Non-Hodgkin lymphoma

Diffuse lung disease

• PCP
• PCP + infection
• Mycobacterium tuberculosis
• Fungal infection
• NSIP
• Lymphocytic interstitial pneumonia
• Kaposi sarcoma

Nodules

• Non-Hodgkin lymphoma
• Kaposi sarcoma
• Septic emboli
• Mycobacterial/fungal infection

Adenopathy

• Mycobacterial/fungal infection
• Kaposi Sarcoma
• Non-Hadgkin lymphoma
• PCP

Pleural Effusion

• Kaposi Sarcoma
• Mycobacterial/fungal infection
• Non-Hadgkin lymphoma
• Pyogenic empyema
• PCP

Wegener’s Granulomatosis

• necrotizing vasculitis
• upper respiratory tracts, lungs, renal glomeruli
• lungs
  • multiple pulmonary nodules; 50% cavitate, angiocentric
  • diffuse alveolar consolidation = hemorrhage
• +cANCA
• Rx: cyclophosphamide and steroids

Solitary Pulmonary Nodule Workup

• Nipple? Use nipple markers…it’s cheap and fast.
• 3cm = mass
• 95% fall into 1 of 3: malignant neoplasm, infectious granulomas, benign hamartoma
• Always: Look at AP/LA views; Look for old studies
• What to think about:

1. Clinical ( 35yo)
2. Growth pattern (doubling time)
3. Size (not reliable)
4. Margins
5. density

Most likely B9 if:

• Calcium (extremely rare eccentric scar carcinomas and carcinoid tumors) or fat present (hamartoma)
• well circumscribed

Volume Doubling time (increased diameter by 25%):

• 1-24 months = bronchogenic carcinoma
• >24 months = granuloma, hamartoma, bronchial carcinoid, salivary gland adenoid cystic carcinoma, thyroid carcinoma met, round atelectasis, adenocarcinoma, carcinoid tumors

Margins
Smooth, well circumscribed

• Most likely benign = granuloma, hamartoma
• Rare malignant causes = carcinoid tumor, adenocarcinoma, solitary met

– Other (notched, lobulated, spiculated)

• Strongly suggestive of malignancy, but not diagnositic
• B9 causes = lipod pneumonia, organizing pneumonia, TB, progressive fibrosis from silicosis
• Differentiate round atelectasis (on CT):
  • Comet tail of bronchi and vessels swirling around density
  • Crow’s feet branching from consolidation to lung parenchyma
  • Associated with pleural effusion or pleural disease (ie asbestos)
  • Lung bases predominate

Density ( most important factor)

• Calcification pattern:
  • B9 = central, complete, concentric/laminated, peripheral, or popcorn
  • Bronchogenic Carcinoma = eccentric internal calcification (engulfment)

• Fat = harmartoma

Contrast Enhancement

• Virtually all malignant lesions enhance 15HU
• Lack of significant enhancement = B9

PET

• FDG-PET has high sensitivity and specificity for lesions >10mm (97% and 78%), for being malignant

Fleischner Society Guidelines: Radiology 2005 Nov; 237:395-400.

Low risk patients

• < or = 4 mm: No follow-up needed.
• >4 – 6: Follow-up at 12 months. If no change, no further imaging needed.
• >6 – 8: Initial follow-up CT at 6 -12 months and then at 18 – 24 months if no change.
• >8: Follow-up CTs at around 3, 9, and 24 months. Dynamic contrast enhanced CT, PET, and/or biopsy.

High risk patients

• < or = 4 mm: Follow-up at 12 months. If no change, no further imaging needed.
• >4-6: Initial follow-up CT at 6 -12 months and then at 18 – 24 months if no change.
• >6-8: Initial follow-up CT at 3 – 6 months and then at 9 -12 and 24 months if no change.
• >8: Follow-up CTs at around 3, 9, and 24 months. Dynamic contrast enhanced CT, PET, and/or biopsy.

Management Algorithm

Differential Diagnosis

Multiple Pulmonary Nodules

• Mets
• **Infection (Histoplasmosis) **
• Lymphoma (non-Hodgkins, + gallium scan)
• Bronchogenic Carcinoma
• Kapsoi’s sarcoma (+HIV)
• Granulomatous Disease
• Sarcoidosis
• Wegener’s Granulomatosis
• RA
• Amyloid
• Septic emboli

lung

Solitary Pulmonary Nodule Differential

Neoplasm

• bronchogenic carcinoma
• hamartoma
• adenoma
• granular cell myoblastoma
• mesenchymal neoplasm

Infection

• septic emboli
• round PNA
• abscess
• granuloma (TB, histo)
• parasitc

Collagen Vascular Disease

• RA
• Wegener’s

Vascular

• Infarct
• AVM
• Pulmonary artery aneurysm (Rassmussen)
• hematoma

Airways

• congenital foregut malformation
• bronchogenic cyst
• sequestration
• mucocele
• infected bulla

Other

• amyloid
• round atelectasis