Micronodules

2-3mms

random

centrilobular- do not touch the pleural surfaces

discrete solid

infection

aspiration

silicosis

Langerhans Cell Histiocytosis

ground glass

hypersensitivity pneumonitis

bronchiolitis

respiratory

infection (viral)

adenocarcinoma (BAC)

organizing pneumonia/NSIP

vasculitis

edema

tree in bud

Atypical TB

virus

bacterial

aspiration

perilymphatic

along the bronchovascular bundle

along interlobular septa

pleural surface

fissural surface

Cause most commonly sarcoidosis

lymphangitic disease

When perilymphatic is clustered highly suspicious of sarcoidosis otherwise perilymphatic dd is silicosis

Random distribution

- random nodules in the vascular distribution and lymphatic
- lower lobes (that is where blood flow goes)
- solid
- well defined
- +/- feeding vessel sign
- +/- cavitation
- +/- lymphangitic appearance
Causes
- Metastases
  - renal
  - melanoma
  - thyroid
  - testicular
- Miliary
  - TB
  - Fungal
    - - coccidiomycoses
      - histoplasmosis
      - pneumocytis
    - Viral

Histoplasmosis

MIP IMAGE SHOWING EXTENSIVE MICRONODULES – ACUTE MILIARY PULMONARY HISTOPLASMOSIS
22-year-old female presents with flu like symptoms and has a normal CXR
3 weeks later a chest CT shows extensive diffuse bilateral micronodular military disease associated with mediastinal lymphadenopathy, and hepatosplenomegaly.
A week later she was admitted to the ICU with confluent pneumonic infiltrates with air bronchograms in the lower lobes.
Later that month her CXR started to improve but still showed military disease.
A CXR 9 months later shows resolution.
Ashley Davidoff MD

ACUTE PULMONARY HISTOPLASMOSIS – PNEUMONIA
22-year-old female presents with flu like symptoms and has a normal CXR
3 weeks later a chest CT shows extensive diffuse bilateral micronodular military disease associated with mediastinal lymphadenopathy, and hepatosplenomegaly.
A week later she was admitted to the ICU with confluent pneumonic infiltrates with air bronchograms in the lower lobes.
Later that month her CXR started to improve but still showed military disease.
A CXR 9 months later shows resolution.
Ashley Davidoff MD

ACUTE PULMONARY HISTOPLASMOSIS – 1 WEEK LATER IMPROVING
22-year-old female presents with flu like symptoms and has a normal CXR
3 weeks later a chest CT shows extensive diffuse bilateral micronodular military disease associated with mediastinal lymphadenopathy, and hepatosplenomegaly.
A week later she was admitted to the ICU with confluent pneumonic infiltrates with air bronchograms in the lower lobes.
Later that month her CXR started to improve but still showed military disease.
A CXR 9 months later shows resolution.
Ashley Davidoff MD

ACUTE PULMONARY HISTOPLASMOSIS RESOLUTION 9 MONTHS LATER
22-year-old female presents with flu like symptoms and has a normal CXR
3 weeks later a chest CT shows extensive diffuse bilateral micronodular military disease associated with mediastinal lymphadenopathy, and hepatosplenomegaly.
A week later she was admitted to the ICU with confluent pneumonic infiltrates with air bronchograms in the lower lobes.
Later that month her CXR started to improve but still showed military disease.
A CXR 9 months later shows resolution.
Ashley Davidoff MD

MICRONODULES IN ILD

NODULAR PATTERN ON CXR IN ILD
Frontal view exemplifies a diffuse nodular pattern of ILD such as is seen in silicosis and sarcoidosis

NODULES IN ILD
Micronodules in ILD is another CT feature of interstitial lung disease and is characterised by nodules of a variety of shapes and sizes and likely centrilobular in origin. Sometimes they are ill defined such as in this case.

42-year-old cement worker presents with dyspnea .
A CXR performed 5 years prior was close to normal with possible right hilar prominence.
The CT scan, shows diffuse micronodular lung disease, predominantly in the upper lobes with mediastinal widening consistent with mediastinal lymphadenopathy, dominant in the right paratracheal region and in the subcarinal region.
Lung windows show the presence of extensive diffuse micronodular disease accumulating along lymphatics along fissures and pleural surfaces, and along the bronchovascular bundles. Although there is diffuse disease, the upper lobes are slightly more involved than the lower lobes. The extensive thickening along bronchovascular bundles and prominent adenopathy favors a diagnosis of sarcoidosis but with a work history of being a cement worker, silicosis still remains in the differential diagnosis as a less likely possibility.