Fundamentals of HRCT - Nodular lung disease

Question 1

what are the 3 considerations when forming a ddx for a nodular pattern on HRCT?

Answer 1

1) cradiocaudal 2) well defined vs not well defined and 3) relationship to other lung structures

Question 2

what is the differential for upper lobe (5) vs lower lobe (1) vs no preference (7)

Answer 2

upper lobe nodules - SARCOID, pneumoconiosis, langerhans cell histiocytosis, respiratory bronchiolitis, miliary TB

lower lobe - hematogenous spread of mets

no preference - lymphangitic carcinomatois, HP, endobronchial infection spread, invasive mucinous adeno, miliary TB, miliary fungal, follicular bronchiolitis

Question 3

what is the differential for well defined (4) vs ill-defined (10) nodules?

Answer 3

well defined = interstitium = sarcoid, mets, miliary infection, amyloid

ill defined = alveoli = HP, respiratory bronchiolitis, follicular bronchiolitis, infection, invasive adeno, aspiration, edema, hemorrhage, PAH, metastatic calcification

Question 4

where are the 4 areas of “perilymphatics” in the lung

Answer 4

1) parahilar peribronchovascular interstitium
2) subpleural intersitium
3) interlobular septa
4) centrilobular peribronchovascular intersitium

Question 5

ddx of perilymphatic nodules

Answer 5

sarcoid, lymphangitic spread, lymphoma/leukemia, pneumconiosis, LIP, amyloid

Question 6

when nodules are randomly distributed, what does that imply?

Answer 6

hematogenous spread

Question 7

what is the ddx of random nodules

Answer 7

miliary tb, miliary fungal infeection, hematogenous spread

consider perilymphatic

Question 8

what are some characteristics of centrilobular nodules

Answer 8

they spare the subpleural interstitium and are relatively evenly spacced

Question 9

what is the ddx for centrilobular nodules that are ggos?

Answer 9

HP, RB-ILD, infection, follicular bronchiolitis, pneumoniosis (siderosis, CWP)

Question 10

ddx for centrilobular nodules that are soft tissue

Answer 10

bronchpneumonia (any type), endobronchial tumor spread (mucinous adeno), edema, hemorrhage

Question 11

what does tree in bud signify?

Answer 11

aspiration or infection, rarely mucinous adeno, follicular bronchiolitis, mucoid impaction in asthma, ABPA

Question 12

what are the 3 different relevant distribution patterns with respect to other lung structures?

Answer 12

1) perilymphatic, 2) random 3) centrilobular

Question 13

how do sub pleural nodules narrow down your ddx?

Answer 13

cannot be centrilobular

Question 14

what type of distribution pattern is tree in bud found in?

Answer 14

centrilobular