---start medsurg.03.17.98----

medsurg
3/17/98
saunders

Pleura, Pleural 
space: we do not see normal pleura radiographically. the pleura have two 
parts - the visceral/pulmonary pleura, lining the lungs, and the parietal 
pleura, which itself is divided into three sections and lines the chest 
wall. the part lining the chest wall is the costal pleura. the part at 
the costophrenic angle and beyond becomes diaphragmatic pleura, and then 
up in the mediastinum it's called the mediastinal pleura. In between the 
pleura is the pleural space - a potential space in normal animals, which 
contains a little bit of fluid. Normally we don't see this. we only see 
it when it becomes abnormal. the two abnormalities to discuss today are 
pleural effusion (fluid in the space) and air in the space - 
pneumothorax.

Pleural effusion: fluid is equal to soft tissue in 
opacity, you recall from radiology. Air = black; bone/metal = white. in 
between is fat, soft tissue/fluid, then bone, then metal. so, effusions 
in the pleural space cause the chest rads to look more opaque than 
normal. you don't see the normal black lung fields filling the chest 
cavity. 

slide: increased opacity in chest of animal with pleural 
effusion. edges of lungs are visible. lungs are slightly atelectatic and 
slightly more opaque than they should be due to collapse. the edges of 
lungs contrast with the soft tissue density fluid in the pleural space. 
this is why we see the borders. normally the lungs are totally filling 
the chest and you can't see the lobulated edges of the lungs, but with an 
effusion you can. the effusion accumulates between chest wall and lungs, 
and between the lung lobes, between the layers of pulmonary pleura. you 
get little detail in a chest rad when there is an effusion - fluid 
obscures the heart, diaphragm, caudal vena cava - anything with soft 
tissue density in the chest is obscured. this radiograph is a lateral 
taken with the dog on its side - so there's no fluid line. you see the 
effusion even around the dorsal portions of the lungs. you see it both 
dorsal and ventral to the lobes when dog is lying down. with an effusion, 
there is separation of lobes from chest wall and from each other, and 
there is collapse/partial collapse of the lobes, and an obscured cardiac 
sillhouette and diaphragm.

slide: VD view - increased soft tissue 
opacity, very homogeneous. pleural fissures are visible,fluid is 
accumulating between lobes. heart is obscured, you don't see the 
diaphragm. everything is obscured. now, if you have  other abnormalities 
like a traumatic diaphragmatic hernia, you may also have a pleural 
effusion - which makes it hard to tell if the diaphragm is intact or not. 
so this can make it hard for you to interpret the situation.

small 
amounts of effusion can be hard to pick up.

slide: cat with small amount 
of pleural effusion. there is a scalloped appearance the the ventral lung 
border - pleural fissures. a very small amount of fluid accumulating in 
pleural space and separating the lung lobes by small amounts of fluid. 
the lines called "pleural fissures" are also visible - the lines 
separating the lung lobes. there are 4 lobes on the right, and two on the 
left. you can use the appearance of fissures to see wherefluid is 
accumulating. the right middle lung lobe is triangular, and it's outlined 
well in this radiograph. we  can also see the right cranial and right 
caudal lobes outlined by the visible pleural fissures caused by an 
accumulation of fluid. 

in some older dogs you'll see pleural fissures 
due to pleural fibrosis associated with age, or due to prior disease. in 
those cases,the lines are more distinct than with an effusion. there is 
no evidence of effusion in those cases, it's just pleural thickening.


slide: rad of chest of dog with pancreatitis and pleural effusion 
secondary to abdominal inflammation causing diaphragmatic inflammation 
and diaphragmatic pleural effusion. here we see increased soft tissue 
opacity in the chest on a lateral view, no real lines as in other view, 
though.
slide: DV of same dog. now we do see pleural fissures, and fluid 
is totally obscuring the heart and the diaphragm
slide: VD view of same 
dog. now we see fluid b/w chest wall and lungs, a couple of pleural 
fissures, and we see the heart pretty well, and the diaphragm. 

why the 
difference in appearance of the DV and VD? well, with dog on sternum,for 
the DV, the fluid is sitting adjacent to the heart, the lungs are 
floating up on top,the ventral chest is more narrow so the fluid rises 
higher,and collapses the lungs more against the back of the dog. you 
can't see the heart because it's surrounded by fluid. with the dog on its 
back, fluid sits in the paravertebral/paraspinal gutters. lungs float up 
to surround the heart, so you can see the heart better, and the diaphragm 
also. you still see signs of pleural effusion since fluid accumulates 
between lungs and chest wall.

so if you know the dog has a pleural 
effusion, do a VD view, not a DV view. if animal has severe respiratory 
compromise people often prefer to do a DV, but in case of pleural 
effusion, the DV doesn't offer much diagnostic clue, so you often have to 
do the VD if the dog can handle it.

most pleural effusions are 
bilateral. remember the mediastinum in small animals, dog/cat, although 
anatomically complete is functionally incomplete. has some small 
fenestrations. air/fluid can migrate from left to right relatively 
freely. most pneumothoraces and effusions are bilateral. we can't look at 
the rads and dx the type of effusion,either. you need to do a cytologic 
evaluation or fluid evaluation. 

exception - unilateral pleural effusion 
may be seen with hemorrhage or pyothorax, or in animals with chronic 
effusions due to fibrosis of mediastinal pleura and lack of communication 
b/w left and right pleural spaces.

slide: unilateral pleural effusion - 
lungs against chest wall on right. VD view. soft tissue opacity filling 
left hemithorax. this is a puppy with a pyothorax. you'd consider 
hemothorax or pyothorax when you have acute presentation of unilateral 
pleural effusion. if it's chronic, and one sided,it might be just due to 
fibrosis. 

slide: gross presentation of puppy above - normal on right, 
thickened pus covered pleura on left. 

Pneumothorax: accumulation of air 
within pleural space. this is similar to air in the lungs - black. so the 
radiograph looks blacker than normal. Also, on a lateral radiograph, 
you'll see separation of the heart from the sternum because air in the 
pleural space causes partial collapse of the lungs. the air in the 
pleural space pushes the lungs, which collapse, allowing the heart to 
fall away from the sternum. heart is more dorsal, because lungs aren't 
fully expanded keeping heart in place, and when dog lies on the side, the 
heart rolls back on the down chest wall. so you have increased opacity of 
the collapsed lobes, too. you can notice that the lobes are separated 
from the chest wall if the lobe is atelectatic and exhibiting increased 
opacity. 
so, chest looks radiolucent, heart is away from sternum, and 
using a bright light behind the radiograph, you can see that the air near 
the chest wall is free of pulmonary/interstitial markings, and is just 
total blackness, and you also see edges of lung lobes retracted from 
chest wall.

slide: pleural effusion - increased soft tissue opacity, 
separation of lungs,fluid in pleural fissures

slide: pneumothorax - 
black, black chest, heart away from sternum - apex should be down on 
sternum, lung lobe edges are separated from chest wall. free gas within 
pleural space.

how does air enter pleural space? can come through chest 
wall secondary to trauma - "open" pneumothorax (chest wall is open). or, 
can be "closed" pneumothorax - chest wall is intact, and air comes from 
ruptured trachea,or lacerated lung lobe, or ruptured bullae (gas pockets 
in lung not associated with alveoli). with open pneumothorax, there is 
often concurrent subq emphysema. in either condition, there is a third 
thing called "tension" pneumothorax, and  then there is some kind of 
valve created by a tissue flap which allows air to get sucked in during 
inspiration through the tear or hole, but which closes off during 
expiration, so that air is trapped within the pleural space. it goes into 
pleural space on inspiration,can't get out on expiration, causing more 
air to fill pleural space, and increased pressure within pleural space, 
beginning to reach atmospheric pressure - intrathoracic pressure rises, 
normal negative pressure is lost, animal has increasing dyspnea as it 
gets harder and harder to breathe. radiographically, the lungs get very 
collapsed and atelectatic with increased opacity of lobes. the heart will 
get smaller and smaller as well, since normal negative pressure allows 
better venous return, and as intrathoracic pressure increases there is 
decreased venous return. also with tension pneumothorax, the chest itself 
expands beyond normal limits - the diaphragm is pushed caudally, it loses 
its normal contour and gets flattened instead of dome shaped, or inverted 
V shape on the VD view, as it gets pushed against costal attachments. 
sometimes there is scalloping of the diaphragm. the chest will look very 
wide, and ribs will look perpendicular to the spine on the VD view - 
because it is hyperinflating the thorax. sometimes the opacity of the 
lungs in a very collapsed state will approach soft tissue - then the 
lungs may look like liver lobes. 

slide: tension pneumo, hyperinflated 
chest, as described above
slide: after air removed from thorax - still 
have pneumothorax, heart still separated from sternum, can barely make 
out tips of lung lobes. diaphragm more normal dome shaped appearance, 
width of chest reduced. this is after release of tension within pleural 
space. note that tension pneumo can occur with open or closed pneumo. 
this one was closed, due to torn lung or something. 

radiographic 
features of tension pneumo
wide chest, black lungs, small heart, 
collapsed lungs, abnormal diaphragmatic countour, perpendicular ribs. 
bilateral tension pneumothorax often results in death prior to arrival at 
the hospital. so sometimes, you'll see unilateral tension pneumothorax.


Mediastinum: defined by two layers of mediastinal pleura and potential 
mediastinal space and structures within it. bounded by two layers of 
mediastinal pleura. in some areas, mediastinal space is potential space, 
and in other areas there is real space - heart, caudal vena cava and 
aorta are all in the mediastinal space. note that the space is contiguous 
with the fascial planes of the neck, and caudally through aortic hiatus 
into the retroperitoneum. pneumomediastinum can be associated with air 
migrating into neck or retroperitoneum.

slide: lateral chest rad. you 
can't see the "mediastinal space" on a lateral, because it runs midline 
the length of the chest - but you can see structures within it. We see 
the heart, trachea, aorta, descending aorta, and caudal vena cava. those 
are the mediastinal structures we normally see. there are others we do 
not normally see - the esophagus (only visible if something is in it like 
food, air, FB), the cranial vena cava (sometimes you see the ventral 
border), the aortic arch,  the brachiocephalic and left subclavian 
branches, lymph nodes (3 tracheobronchial LNs (or "hilar" LNs), the 
cranial mediastinal LNs, and the sternal LNs at second or third 
sternebra). you don't see the LNs unless they are large. 

you need a DV 
or VD view to place structures within mediastinum.

slide: VD view - we 
see heart, descending aorta. cranial mediastinum is seen cranial to 
heart, midmediastinum is where heart is, and caudal to heart is caudal 
mediastinum. on VD we see cranial broad band of soft tissue opacity 
blending with heart, running up to thoracic inlet - this is the 
"mediastinal width" created by the trachea which is to the right of 
midline, the cranial vena cava, esophagus, LNs, aortic branches - and 
normally, the width should be 1 to 1.5 x the width of the vertebral 
bodies. in fat dogs, mediastinum widens but doesn't bulge like it does 
with masses in it. 

slide: back to the lateral view. note that the chest 
is very dark ventrally, where the layers of mediastinal pleura press 
against each other and ventral to that. 

slide: back to the VD - the 
cranial/ventral mediastinal reflection, where the mediastinal pleura 
press against eachother and nothing is within mediastinum - shows up as 
thin opaque line. the dorsal mediastinum is what creates the width. there 
is also a caudal ventral mediastinal reflection where the caudal 
mediastinal pleura press against each other. you see this in normal 
animals. used to be called the cardiophrenic ligament, incorrectly. but 
it's really the caudoventral mediastinal reflection, a normal pleural 
fissure. 

in puppies only, we see the thymus in the mediastinum (uh, 
kittens  too, right?). the thymus starts regressing in dogs at about 5 
mos of age. in puppies, it's a triangular shaped orggan in the cranial 
ventral mediastinal reflection. often called the "sail sign" because of 
the shape. it's on the left in this film. you don't really see it in the 
lateral, maybe you see a vague opacity cranial to the heart.

slide: 
diffuse mediastinal widening. not usually seen.usually due to 
inflammation from cervical fascial planes or from mediastinal 
inflammation or due to accumulation of blood. this slide is labeled 
"mediastinitis" - diffuse soft tissue opacity dorsally, trachea deviated 
ventrally. on the VD view we see enlargement of the cranial dorsal 
mediastinum. trachea is bowed to the right. it never deviates to the left 
because the aortic arch is in the way. this animal isn't fat, yet it does 
have a wide mediastinum.  we know it's dorsal cranial thickening. 


slide: dog from above slide after being on antibiotics. trachea isn't 
deviated anymore. mediastinum has returned to normal width on VD view. 


Mediastinal masses: more common than diffuse mediastinal widening. causes 
focal widening. most masses arise within cranial mediastinum

slide: lat 
chest rad. soft tissue opacity where we should see right and left cranial 
lung lobes. heart is elevated off sternum due to mass - probably this is 
enlargement of sternal and cranial mediastinal LNs - this dog has LSA. 


slide: VD view - marked thickening of cranial mediastinum, more of a 
ventral mass, elevating the trachea so it doesn't deviate away from the 
spine. same dog as in above slide. the enlarged LNs drive trachea 
dorsally, elevate heart,and cause marked thickening of cranial 
mediastinum in non-fat dog.

slide: cat with cranial mediastinal mass - 
trachea elevated slightly but not compressed. also a pleural effusion - 
lungs separated from chest wall and somewhat collapsed.  note tracheal 
bifurcation should be at 5th or 6th intercostal space, but here the 
carina is pushed back by the mass to 7th or 8th space. the mass is 
obscured by pleural effusion in the VD view. there's no expansion of lung 
lobes into cranial thorax at all. the effusion is pushing the lungs back, 
as is the mass. 

slide: ultrasound of chest - see large LNs. they did 
u/s guided aspirate of the LNs in the chest. this is much easier than 
what they used to do (drain the fluid and re-xray).

slide: after ten 
days of chemo - marked regression of lymphadenopathy, clearance of 
pleural effusion.

---break----

note: it's rare to see diffuse widening 
of the mediastinum outside of the cranial mediastinum. when we see 
widening of the cranial mediastinum due to masses, it's generally more 
focal. diffuse mediastinal widening is usually due to fat animal or 
infection or hemorrhage.

slide: enlarged tracheobronchial LNs, 
craniomediastinal LNs, and sternal LNs. the opacity dorsal to heart is 
tracheobronchial lymphadenopathy. this causes ventral deviation of 
mainstem bronchi which is visible here. left atrial enlargement of heart 
would cause dorsal deviation of mainstem bronchi. the sternal 
lymphadenopathy appears as a soft tissue density extrapleural sign type 
image on the sternum (broad based mass against chest wall). some dogs 
with LSA will have this kind of thing going on.

Pneumomediastinum: air 
in mediastinal space. because it's contiguous with cervical fascial 
planes and retroperitoneum, air in mediastinum can come from 
something 
in the mediastinum like trachea or esophagus or cervical fascial planes - 
eg, secondary to bite wounds in neck, excessive venipuncture, and so 
forth. air migrates down into mediastinum. how do you know where air is 
coming from? look at relative amounts of air. if there is more in 
mediastinum than in neck, look in mediastinum for a problem. if there is 
more in the neck, look in the neck. pneumomediastinum is usually not a 
problem, it's an observation, a manifestation of other problem like neck 
trauma. it's only a problem if it gets large enough to produce a 
pneumothorax, if air gets into the pleural space. it's rare for 
pneumothorax to produce pneumomediastinum - almost impossible. 

slide: 
an early, mild pneumomediastinum. radiographic signs include: because air 
is in mediastinum, the structures you don't normally see in there like 
esophagus, cranial vena cava, etc, start to show up. this dog swallowed a 
fish hook which is visible in the esophagus. ventral to the trachea we 
see some free gas, also some above the dorsal border of the trachea. 
small amounts of air accumulate along ventral border of trachea so we can 
see the tracheal wall defined by air along both sides. so we know the 
hook ruptured the esophagus. there's no air in the fascial planes of the 
neck. 

because esophagus isn't sterile, this dog also had mediastinitis 
and pleural effusion on left side of thorax. there's overall increased 
opacity on left, pleural fissures visible. probably there's some fluid in 
pleural space, and small pneumomediastinum.

slide: another example of a 
little air in mediastinum. we see the ventral border of trachea, and we 
see dorsal border and ventral border of ventral tracheal wall, outlined 
by air. this is the first sign of air in the mediastinum for some reason.


slide: large amounts of air in mediastinum creating overall lucency 
within chest and increased visualization of mediastinal structures - 
trachea, esophagus, aorta, cranial and caudal vena cava, all are more 
obvious. left subclavian and brachiocephalic are sort of visible although 
we can't see them at this time :). there's also a lot of air in fascial 
planes along the dorsum, greatly elevating skin off the top of the 
radiograph. not sure where the air is coming from. dog was HBC. turned 
out to be ruptured trachea with air migrating out thoracic inlet. this 
dog also seems to have pneumothorax, because heart is shifted up off the 
sternum. remember, pneumomediastinum can cause pneumothorax, but 
pneumothorax compresses mediastinal pleura together and can't really 
cause pneumomediastinum. 

slide: bad case of subq emphysema - lots of 
air in fascial planes of neck, whole animal's skin is elevated by air!, 
pneumothorax also present - free air in pleural space, lungs very opaque, 
increased visualization of mediastinal structures - this much air almost 
ahs to be due to ruptured trachea - this much air wouldn't come from 
anywhere else. extensive subq emphysema and large large pneumomediastinum 
is generally from ruptured trachea. this animal also has 
pneumoretroperitoneum due to vast amount of air in mediastinum - air 
migrates along aorta. we see air deflecting the kidneys ventrally. this 
animal had bilateral chest tubes placed and a chest wrap.

Mediastinal 
Shift:

sounds inconsequential, but is not. valuable in looking at 
pulmonary disease, trying to figure out if mediastinum is shifted from 
left to right. only two processes allow this - either it falls to the 
side due to a decrease in volume on one side of chest, or it gets pushed 
to one side by an increase in volume or pressure on one side of the 
chest. so you have either a loss of lung lobe volume or an increase in 
volume created by tension pneumothorax or pulmonary mass or gross 
accumulation of fluid.

slide: lat chest rad - looks like pneumothorax. 
heart apex is dorsal to sternum - but space isn't radiolucent, it's 
actually looking like lung parenchyma. there's no retraction of lung away 
from chest wall. on the VD view, the heart is shifted towards the left 
side of the chest. the heart is normally midline, with the apex sitting 
midline or slightly left of midline. but now, the apex of the heart is 
far left. the heart is the easiest thing to use to detect mediastinal 
shift. this dog was probably lying on the left side for a while. lungs 
are more opaque on left side than the right. one cause of mediastinal 
shift is prolonged lateral recumbency producing atelectasis of down lobes 
and hyperinflation of the up lobes. sick, recumbent animals often have 
this occur. it's very pronounced during general anesthesia. 

slide: dog 
under general anesthesia that's been lying on left side. you're really 
just inflating the up lobes and not the down lobes - you see atelectasis 
of down lobe and hyperinflation of up lobes and mediastinal shift over to 
the down side. so if you need chest rads you should have the anesthetist 
bag the animal a few times to eliminate this effect.

slide: rad from the 
pyothorax puppy - pleural effusion was all on the left, you may recall, 
and the heart is pushed way way over to the right. there is a lot of soft 
tissue density on the left, and it has to be space occupying because it 
is pushing the heart over to the right. if it were increased opacity 
because the lungs were atelectatic, the heart would be shifted over 
towards the atelectatic lungs, not away from them. 

Abnormal Pulmonary 
Patterns:

alveolar
interstitial
bronchial
vascular
mixed

this is one 
aspect of looking at a chest rad, but is often a big stumbling block for 
students in clinics. it's hard. what's evolved in radiographic exam of 
lung is that we describe things in lung according to a category of 
pulmonary patterns. the idea is that through experience and research, 
these things correspond to different areas of the lung.

we recognize 
five patterns. the first three correspond to structural lung components. 
alveolar has characteristics relating to alveolar disease. interstitial 
pattern relates to interstitial disease, bronchial pattern relates to 
airway disease. vascular we won't discuss until we talk about cardiac 
disease. mixed patterns are most ubiquitous - some combination of the 
first three. you have to say what the mix is. this is the best 
characterization we've been able to come up with. we correlate the 
radiographic abnormalities with where the actual problem in the lung is. 


think of lung. there are three structural components - major airway 
coming into alveoli, support tissue/stroma, and arteries and veins in 
interstitial spaces. 

Interstitial pattern: this means we see 
accumulation of fluid, cells, abnormal tissue within the interstitium. 
the alveoli are normal, the bronchi are normal, the interstitial space is 
abnormal. this is due to fluid, cellular debris, fibrosis, etc. 
main 
ddx: interstitial fibrosis esp in old dogs, neoplasia esp LSA, pneumonia 
(interstitial pneumonia tends to be viral or hematogenous), pulmonary 
edema, allergy (some acute reaction causing fluid accumulation), 
hemorrhage (hemorrhage in lung produces interstitial pattern at first)


slides: interstitial pattern produced as an artifact of the expiratory 
phase. we always take chest rads on inspiration so lungs are at peak 
expansion for best visualization. at peak inspiration the heart is 
separated from diaphragm. at peak expiration, heart looks enlarged and is 
next to diaphragm. lungs are more opaque than on inspiratory view. we see 
a slight change in opacity of the lungs, a diffuse haziness. there are 
two forms to the interstitial pattern - the reticular or linear type is 
the one that most people are talking about when they say there is an 
interstitial pattern. on an expiratory radiograph, there is an 
artifactual interstitial pattern. pulmonary vessels are less distinct 
since there is increased opacity of the lungs. this reticular form is 
diffuse haziness, increased opacity in the lung, with secondary loss of 
detail of soft tissue structures like vessels, and blurring of borders of 
heart and diaphragm. 

slide: dog with eosinophilic pneumonia due to HW - 
allergic process. there is a subtle increase in opacity, you can still 
see pulmonary vessels but they aren't as distinct as they should be. this 
is a good inspiratory radiograph - heart is away from diaphragm. 
slide: 
post treatment - lungs are more radiolucent even though this rad is a tad 
more expiratory. the haze is gone. (the  haze is gooooone. the haze is 
goooone awaaaayyy....)

slide: LSA dog. LSA sometimes infiltrates 
lymphatics in lungs, causing diffuse interstitial pulmonary pattern. we 
see mottling/haziness of lung lobes. more obvious in caudal region where 
there is more depth of lung for beam to pass through, instead of in 
narrower cranial region. there's lack of sharpness of pulmonary vessels, 
vague haziness.

other interstitial pattern is "nodular" interstitial 
pattern. this isn't' the "default" meaning of "interstitial pattern" 
though. now, we're talking about nodules within the interstitium.

slide: 
nodules can be discrete and easy to see, although we can't seem to focus 
this slide. there are multiple pulmonary masses, multiple well defined 
masses in the lung. this is metastatic pulmonary disease. there are soft 
tissue density nodules over the cardiac sillhouette - they are multiple 
and of varying size. if this were a primary neoplasia it would probably 
be one nodule. this is the nodular interstitial pulmonary pattern, common 
with metastatic neoplasia.

normal chest rads include left and right 
lateral and VD. why? well, most abnormalities are soft tissue ones within 
the lung. you see them best when they are surrounded by aerated lung. 
this is due to contrast between normal lung and the mass or infiltratoin 
causing the opacity. when you put a dog in lateral recumbency, the down 
lung is atelectatic and the up lung is well aerated. you see 
abnormalities best in the up, aerated lung. if a pneumonia or nodue is in 
the down lung, you may not see it.

slide: right lateral - no nodules 
seen.
slide: left lateral - two pulmonary nodules seen over the cardiac 
sillhouette.
these are in the right, up lung.
slide: VD of same animal - 
nodules are present in parenchyma of right lung.

we always do three 
views because it increases our sensitivity for picking up abnormalities.


slide: primary pulmonary neoplasia - large mass in caudal lung lobe with 
multiple smaller masses - the one large mass is likely to be a primary 
pulmonary neoplasia. when you see one large well defined pulmonary mass 
it is  likely to be a primary. the multiple small ones are likely to be 
metastatic.

some pulmonary masses are hard to pick up as masses. this 
lateral radiograph of a young puppy shows a nondescript soft tissue 
opacity, probably pleural effusion. it's all over ont he right, causing a 
mediastinal shift from right to left,there seems to be a mass pushing 
heart against left chest wall.this is technically a nodular interstitial 
pulmonary pattern but we have to consider it a mass. granulomas are rare. 
it could be an abcess
metastatic neoplasia
primary neoplasia
abcess

granuloma
are the ddx for nodular interstitial pulmonary disease. this 
one was  an abcess secondary to lung lobe torsion.

slide: dog with 
blastomycosis from someone at Auburn - there are multiple poorly defined 
pulmonary opacities within the lung, starting to coalesce into larger 
nodules. this is a granulomatous nodular infiltrate. some people call 
this a reticular-nodular pulmonary pattern, or miliar nodular pulmonary 
pattern. technically, it's still a nodular pulmonary pattern. we don't 
see these granulomatous lung patterns around here. when we see pulmonary 
nodules in the lung we think neoplasia based  on geography. in other 
areas, there is  more fungal disease.

slide: benign nodules in the lung. 
there are multiple,very small, well defined,radioopaque nodules probably 
representing calcification. something soft tissue of this size wouldn't 
show up. pulmonary masses have to be about 5 mm in diameter to show up on 
rads. this is heterotopic bone in the lung, also called benign pulmonary 
calcification. another possibility, although these are  too numerous, 
would be end on pulmonary vessels, which create tiny, distinct pulmonary 
opacities. 

slide: gross appearance of benign calcification


----end----