0:00

Let's look at the screening CT

0:02

and a 60-year-old man with a 60 pack cure history

0:05

of cigarette smoking.

0:06

We have the current screening CT on the left from November

0:10

of 2021,

0:11

and we have their prior annual screening CT from

0:14

October of 2020.

0:15

On the right, of course, we're going

0:17

to have our comparison report know what the radiologist said

0:20

before in terms of lung, cardiovascular,

0:23

and center findings, as well as lung nodules.

0:26

And as we're looking at the CT, we can already see

0:29

that there's some mild upper lung predominant emphysema.

0:33

And as we continue down the lung windows, we

0:36

come into a nodule,

0:38

looks like a thick walled cafeteria nodule

0:41

with a little bit of air in it.

0:43

And if we look on the prior exam, there was a smaller

0:47

Cary nodule present before.

0:49

The growth rate of this nodule has been relatively quick.

0:53

It went from being five millimeters on the prior exam

0:57

and now it's 60 millimeters when we've measured it.

1:01

It also has a thick irregular wall

1:04

with a small loosen component,

1:07

and we're gonna look at the soft tissue windows

1:09

to see if there's any other elements to it.

1:12

There's a suggestion of a little bit

1:14

of new calcification along this little edge here,

1:18

this little bright spot.

1:19

There's no artifact that that's in

1:21

that area to be causing that.

1:23

So we've got a growing cavitary nodule with an area

1:25

of cavitation that was a lung RADS three

1:29

before by the cystic cavitary criteria,

1:33

and now it's increased in size.

1:37

So this now makes it a long rans four A.

1:39

And the recommendation is going to be

1:41

to bring the patient back in three months

1:43

to do an interval assessment

1:45

and see if this is continuing to grow.

1:48

Note the growth rate is rapid.

1:50

When we measured the volume of the nodule,

1:53

the volume doubling time could be calculated

1:55

between the two time points and the growth rate of volume.

1:59

Doubling time measured only 76 days.

2:02

Generally the growth rate of lung cancer is between 100

2:06

and 400 days.

2:08

And in many screen detected cancers,

2:10

particularly the ground glass adenocarcinomas,

2:13

the doubling time can be 500, 600, 700,

2:17

or even 800 days.

2:19

They tend to grow very, very slowly. Rapidly.

2:22

Growing nodules under a hundred day growth rate are most

2:25

consistent with infection,

2:27

and here we have fairly rapid growth with a 76

2:30

day volume doubling time.

2:33

So we're gonna bring this patient back

2:34

for an interim assessment.

2:37

So we look at some serial cts.

2:39

Now on this patient we have that baseline

2:40

or comparison lung cancer screening CT

2:43

with a smaller cavitary nodule, the bigger cavitary nodule

2:47

that we just looked at with small area

2:48

of calcification along one edge,

2:51

and now the patient comes back for that interval.

2:54

ct. Looks like it's gotten a little bit smaller in

2:57

size, but if we

2:58

Also look at the internal nodule characteristics,

3:02

it's developed more calcification.

3:04

There's that little calcification we saw

3:06

before on that edge of the cystic component

3:09

or the cavitary component that's gotten bigger.

3:12

And we have new areas of cavitation.

3:14

So this is acting like a healed granulomatous infection.

3:18

Could be tuberculosis,

3:20

could be a fungal infection depending on which

3:22

part of the country you live in.

3:23

With endemic fungus, in particular in my of the country,

3:26

in the upper Midwest, Ohio River Valley,

3:28

it's usually histoplasmosis, but it's gotten smaller

3:32

and it's developing cavitation,

3:34

which is evidence of healing.

3:35

So rapid growth rates suggest infection.

3:38

Now we have evidence of healing smaller in calcification.

3:41

And then when we look at a followup CT

3:43

that was just done more recently, which is now 2024,

3:48

about two and a half years

3:50

after the first CT we were looking at,

3:53

it has shrunk down even further.

3:55

It's gotten much smaller

3:57

and now it's almost completely calcified.

4:00

Just a tiny little soft tissue room along the edge.

4:03

So this is clearly acting like a benign lesion.

4:06

It grew during a phase of active infection

4:09

and then it began to heal,

4:10

develop calcification becomes smaller

4:14

and leave us much smaller footprint.

4:16

So this is an example of infection.

4:18

The patient did have a TB test, was negative.

4:21

This was presumed to be fungal infection due

4:24

to endemic fungus that was healing.

4:26

The patient did not want any intervention

4:28

or bronchoscopy to make a specific diagnosis.

4:31

He did have some positive histoplasmosis antigen

4:35

and titers so that they put that together

4:38

with these findings and considered this to be a diagnosis

4:40

of histoplasmosis.

4:43

Unlike the cases of infection that we call lung rad zero,

4:46

where they obscure enough of the lung

4:48

that we can't clear the rest of the lung from lung cancer,

4:52

and we call a patient back in a short timeframe

4:55

to clear the infection

4:56

and make sure we're not missing an underlying cancer.

4:58

And then rescore using the lung rad schema.

5:01

In this case, we're dealing with a discreet nodule.

5:03

The rest of the lung parenchyma was well evaluated.

5:06

We think it's an infection by its rapid growth rate, but

5:10

because it's a discrete nodular abnormality,

5:12

we categorize this using the lung red schema,

5:14

bring them back for the short term interval, follow up

5:17

and continue to manage accordingly.