Interstitial |
67 |
Findings: Diffuse lines distributed throughout lungs bilaterally. Pattern: Interstitial, specifically lines (reticulations).
Differential diagnosis
L – Lymphangitic metastases (the diagnosis in this case)
I – Inflammation including infection
F – Fibrosis (less likely in this case due to pattern characteristics)
E – Edema (again less likely due to pattern characteristics, distribution)
To help differentiate interstitial lines in this case with normal tapering vasculature using an analogy with tree branching, see Fig. 4.43b comparing to normal left lower lung field.
In Figs. 4.44 – 4.46, you can see how in a CT of lymphangitic spread (here, the same case shown above), lines appear between vessels, like they do in a reticulated giraffe.
Figures 4.47 and 4.48 present another example of a CXR with an interstitial (specifically lines) pattern. This example shows Kerley lines in the LLL peripherally from interstitial edema.
Nodular Form: Dots
Nodules should be differentiated from normal vessels on-end before categorizing in the nodular pattern. See related information on the Mass Considerations at the beginning of this chapter.
Fig. 4.43a Case of lymphangitic spread, showing diffuse lines (all directions, crossing and obscuring vasculature) throughout the lungs bilaterally
68 |
4 Abnormal Lung Patterns |
Fig. 4.43b Compare the normal tapering vessels on CXR (left images) similar to branching of trees to the crossing lines in all directions in our patient (right images). Note the crossing of lines is similar to how cudzu vines cross the normal tree branching, causing lines in all directions
Fig. 4.44 Lymphangitic spread on CT
Processes resulting in nodular interstitial patterns include the following: Remember HGP for this differential (it somehow has a ring to it).
•Granulomatous diseases
•Hematogenous spread of malignancy, miliary disease, lymphocytic interstitial pneumonia (LIP)
•Pneumoconiosis
Interstitial |
69 |
Fig. 4.45 Reticulated Giraffe (photo by Dr. Folio). Note the reticulated pattern that is very similar to the reticulated septal lines on CT
Note: One should consider the differential for mass when categorizing nodules, since they are essentially small masses.
Case 4.15
Figure 4.49 is an example of multiple, diffusely distributed nodules. Note the white dots are even in size, even when going from hila to periphery, ruling out vessels on end. This case represents Miliary Tuberculosis (TB).
Findings: Multiple, diffusely distributed nodules. Pattern: Interstitial, specifically dots.
Differential Diagnosis: Miliary TB, histoplasmosis, coccidiomycosis, silicosis. The miliary nodular interstitial pattern has an extensive differential; however,
you can use TEMPS as a mnemonic to help you remember these causes of miliary interstitial pulmonary nodules [6].
T – TB, fungal, viral pneumonias, tuberous sclerosis
E – Eosinophilic granuloma (EG); see langerhans cell histiocytosis (LCH) M – Metastatic disease (thyroid, renal)
P – Pneumoconioses, parasites S – Sarcoidosis, Silicosis
70
Fig. 4.46 (a) Close-up of the giraffe; then grayscale manipulation (b) to increase the contrast to better simulate septal lines seen on CT (c) ((a, b) created by USUHS ETI Support Office)
4 Abnormal Lung Patterns
Interstitial |
71 |
Fig. 4.47 |
Kerley lines |
(left costophrenic angle in a) on a dual energy (note that the ribs are digitally subtracted) CXR. Also note spine sign on
a
lateral (b) supporting a right pleural effusion with atelectasis
b