Cystic Lung Disease

This post is derived from notes I took during training. Any images are copyright their respective owners.

Cystic Lung Disease

• Lymphangioleiomyomatosis
• Demographics: reproductive age women
• Pathophysiology: mutations of TSC1 & 2. non-neoplastic hamartomatous proliferation of atypical muscle cells that leads to progressive cystic destruction of lung parenchyma
• Associated with recurrent pneumothoraces, chylous effusion, tuberous sclerosis, renal angiomyolipomas, autosomal dominant polycystic kidney disease (gene location closeby)
• Findings: 2 mm thick walled cysts, diffuse smooth walled, without other features of interstitial lung disease
• Treatment: sirolimus

• Pulmonary Langerhans cell histiocytosis
• Inhalational disease associated with smoking
• Lab findings: CD1a, S-100+. Electron microscopy: Birbeck granules
• Findings: upper lobe predominant. Nodules up to 1 cm which cavitate with varied shape “cysts” (really, distorted airways). Spares costophrenic angles. Associated with recurrent pneumothorax
  

  

  
  
  
• Lymphocytic interstitial pneumonia (follicular bronchiolitis)
• Demographics: Men
• Pathophysiology: ball-valve mechanism, peribronchovascular lymphoid aggregates
• Findings: Mid/lower lobe ground glass opacities, centrilobular/subpleural nodules, thickening of septa, perivascular varying 3 - 20 mm cysts with basilar predominance and < 20 in number

References:

• Core Radiology
• Felson's Principles of Chest Roentenology

     

Interstitial Lung Disease

This post is derived from notes I took during training. Any images are copyright their respective owners.

Interstitial Lung Disease

• Questions to ask
• volumes reduced (fibrotic) vs. increased (airways disease)
• distribution upper (trapped inhaled particulates) vs. lower (blood, lymphatic flow)
• central vs. peripheral
• centrilobular vs. septal
• Interstitial disease
• All tend to be related to smoking
• causes peribronchial cuffing, which looks the same as bronchial wall thickening
• Nonspecific Interstitial Pneumonia (NSIP)
• Pathophysiology: homogeneous interstitial inflammation, many started as organizing pneumonia. Many etiologies, including connective tissue disease (*except* rheumatoid arthritis (RA))
• Findings: lower lobe predominance. Subpleural, symmetric distribution of lower lobe patchy ground-glass opacities (GGO) - dominant feature with reticular opacities and limited traction bronchiectasis.

• Usual Interstitial Pneumonia (UIP)
• S l o w l y develop dyspnea, also associated with aspiration
• Pathophysiology: the radiographic finding consistent with clinical syndrome of Idiopathic pulmonary fibrosis (IPF) - see temporal & geographic heterogeneity with fibroblast foci. For connective tissue disease, only RA gives this pattern.
• Volume loss predominates fibrosis → honeycombing (dilated respiratory bronchioles) is collapse, not fibrosis
• Findings: lower lobe peripheral honeycombing with spatial/temporal heterogeneity
• Prognosis: 50% mortality at 3 years; biopsy has high mortality rate
• Acute Interstitial Pneumonia (AIP; aka Hamman-Rich, ARDS)
• Diffuse alveolar collapse with areas of sparing (possibly representing areas of arterial thrombosis) causing reduced volumes over rapid course
• Treatment: Vent on PEEP mode to keep alveoli open
• Constrictive bronchiolitis (Bronchiolitis obliterans)
• Cough, dyspnea, malaise. Radiographically occult usually, may show air trapping/mosaic attenuation
• Causes: diverse inhalational causes (e.g. Iraq lung, popcorn oil, graft-vs-host disease)
• DI: hyperinflation, discrete nodules, mosaicism
• 
• Cryptogenic organizing pneumonia (COP)
• Organization -  histologically, the incorporation of alveolar material into the interstitial wall by fibroblasts, seen in many processes
• Findings: Peripheral consolidations or nodules along bronchovascular bundles with surrounding halo of consolidation (atoll / reverse halo sign - nonspecific), air bronchograms, and sparing of peripheral lung
• 80% likely old infections with progressive scarring

• Smoking related lung disease
• Respiratory bronchiolitis (RB)
• Respiratory bronchiolitis - Interstitial Lung Disease (RB-ILD)
• Macrophages in interstitium causing GGO/nodules in slightly upper > lower lobes
• Desquamative interstitial pneumonia (DIP)

• Demographics: age 30-60s, M:F 2:1
• Pathophysiology: Misleading name because no desquamation of alveolar epithelium present, but rather cells in alveolar space are pigment laden macrophages, thought to represent end-stage of RB-ILD
• Findings: GGO and alveolar opacities, lower lobe predominant, ground glass
• Treatment: steroids
• 
• Scleroderma

• Progressive systemic sclerosis, esophageal involvement (patulous esophagus) (80%), cardiac involvement (40%),
• CXR: fibrosis in lower lobes
• CT: NSIP >> UIP pattern (4:1)
• Prognosis: associated with increased lung adenocarcinoma
• Eosinophilic Pneumonia (EP)
• Can be secondary to unknown causes (Loeffler pneumonia, Acute EP, Chronic EP) versus secondary to known cause (drugs, fungal, parasitic infections)
• Findings:
• Simple / Loeffler: Peripheral ground glass opacities with interlobular septal thickening (ie reverse / photographic negative of pulmonary edema, upper lobe predominance. Positive blood eosinophils
• Acute EP: bilateral GGO and interlobular septal thickening
• Chronic EP: homogeneous peripheral airspace consolidation (reverse bat-wing pattern). Differential diagnosis: Churg-Strauss
• Treatment: Steroids (good response)

References:

• Core Radiology
• Felson's Principles of Chest Roentenology

     

Thoracic Masses and Malignancies

This post is derived from notes I took during training. Any images are copyright their respective owners.

Neoplasms

• Solitary pulmonary nodule (SPN)
• Defined as a lesion < 3 cm, considered benign if stable for 2 years
• 50% benign, 40% primary lung cancer, 10% metastasis
• Signs of benignity
• Fat
• Doubling time <1 mo="" or="">16 months
• Calcification
• PET-CT avid nodules are much more likely to be malignant, although active granulomatous disease can create false positive.  Bronchoalveolar carcinoma (BAC) or carcinoid may create false negative.

• Hamartoma
• Gender ratio M:F 2:3, most asymptomatic
• Benign mass of mesenchymal origin (possibly chromosome 12), containing fat and calcification if degenerating (popcorn pattern)

• Small cell lung carcinoma
• 20% of all lung cancer. Central, rapid growth, early metastasis.
• Associated with Eaton-Lambert syndrome (proximal muscle weakness), paraneoplastic Cushing's syndrome, SIADH
• Adenocarcinoma in situ (Bronchoalveolar carcinoma)
• Peripheral
• FDG poor so not well seen on PET
• Bronchogenic cancer often spreads to adrenal glands
• Synchronous cancers - two separate primaries detected within 6 months of each other without metastases
• Metachronous cancers - two separate primaries diagnosed at separate times without metastases.
• Lymphangitic carcinomatosis - reticulonodular opacities, septal lines, mediastinal/hilar lymphadenopathy
• Inflammatory pseudotumor (inflammatory myofibroblastic tumor) - rare, invasive
• Solitary fibrous tumor of pleura - associated with hypoglycemia and fibrous hypertrophic osteoarthropathy
• Superior sulcus (Pancoast) tumor - associated with brachial plexopathy, pupillary / Horner's syndrome triad (ptosis (lid dropping), miosis (pupillary constriction), anhidrosis (loss of sweating))
• Radiation pneumonitis
• Acute: 1-3 months post treatment, patchy ground glass opacities, lucencies, volume loss
• Chronic: 6-12 months, consolidation, traction bronchiectasis, volume loss

References: