Interactive Transcript
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As I mentioned previously, in the adult,
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the most common masses that are palpated in the
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neck are thyroid nodules and lymph nodes.
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Let's talk briefly about thyroid nodules.
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When you're reading cases in the emergency room,
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particularly cervical spine CT scans for trauma,
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you will find quite a bit of thyroid nodules as incidental
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findings on the cervical spine CT or even
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on a neck CT for other purposes.
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So what are we to do with these incidental
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thyroid nodules which are so prevalent?
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Notice that the palpable thyroid nodule prevalence
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is about 5% in all women and about 1% in men.
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So if you're reading 20 CT scans of the cervical spine in an
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evening, you're going to find thyroid nodules in the women.
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When you look at ultrasound detected thyroid nodules,
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the numbers generally that are referred to are about 40% of all
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comers to ultrasound for the evaluation of carotid stenosis.
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So on your doppler ultrasound of the carotid artery,
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about 40% of individuals show some nodularity in their thyroid
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gland, which again is more common in women than in men.
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Only 5% to 10%, to 15% of thyroid nodules that
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are aspirated are cancerous. And yet,
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because thyroid cancer is such a benign cancer
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with a 95% five-year survival and cure rate,
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it's really an issue that we are over diagnosing thyroid
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nodules and over diagnosing thyroid cancers,
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which in general do not kill you.
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Now, there are some variants of thyroid cancers such as
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anaplastic carcinoma as well as medullary carcinoma,
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which have a worse prognosis.
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But 90% of the cancers are the papillary and follicular
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variety, which are well differentiated and have,
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as I said, about a 95% cure rate at five years.
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When you aspirate the thyroid nodules,
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the vast majorities of these may be hyperplastic nodules,
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sometimes functioning nodules.
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You do have a 10% incidence of about benign adenomas
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and then the carcinomas are about 5% to 10%,
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and those are usually papillary and follicular carcinomas.
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Thyroiditis accounts for about 1% to 5%.
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And sometimes you will have lesions in the thyroid gland
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that are secondary to parathyroid adenomas
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or metastases to the thyroid gland,
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or pure follicular or colloid cysts.
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Again, as you get older,
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you see that the incidence of nodularity within your thyroid
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gland increases and increases. At autopsy specimens,
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in a person who is 70 years old,
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the rate at which you find thyroid nodules is 60%.
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Now, these are nodules. These are not cancers.
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So in autopsy specimens of 70 year olds,
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you'll probably find about a 15% rate of incidental papillary
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carcinomas of the thyroid glands relatively
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common incidental diagnosis,
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but never spreads from the thyroid gland
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into the adjacent tissues or lymph nodes.
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My colleague Jenny Hong,
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who I mentioned previously in the publication on retropharyngeal space,
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has done a really great job in creating an algorithm that is
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supported by the American College of Radiology for
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the evaluation of incidental thyroid nodules, or ITNs.
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And this is from that ACR white paper.
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What they said was that if there are suspicious CT
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or MRI findings of this incidental thyroid nodule,
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those suspicious findings being spread outside the thyroids
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capsule or adjacent lymph adenopathy, or
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invasion into the trachea or esophagus,
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that patient should be immediately evaluated with
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thyroid ultrasound and subsequent
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cytology or aspiration histology.
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If, on the other hand,
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it's just a nodule that is identified within the thyroid
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gland, without suspicious CT or MRI findings,
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we separate them into those that occur in less than 35 year
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olds and those that occur in greater than 35 year olds.
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Of those that are less than 1 cm in a patient less
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than 35 years old, we usually don't do anything.
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However, if it's greater than 1 cm,
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it will be evaluated with thyroid ultrasound, and based on
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TI-RADS, the evaluation of the thyroid nodule by ultrasound,
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it may or may not go on to aspiration cytology.
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However, in the patients who are greater than 35 year olds,
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we use a different marker, and that is 1.5 cm.
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If it's less than 1.5 cm in a 70-year-old,
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we say no further evaluation.
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If it's greater than 1.5 cm in a 70-year-old,
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you would evaluate that with thyroid ultrasound.
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And depending upon its characteristics on thyroid
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ultrasound, it would get aspirated or biopsied.
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So this is the age criteria as well as the size criteria that
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the American College of Radiology recommends for
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separating those that get evaluated
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with ultrasound versus not. Now,
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you notice that there's a little sidebar over here.
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Those patients who have other comorbidities that are life
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threatening, IE, they already have a nasopharyngeal carcinoma,
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or they already have congestive heart failure that is
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associated with a high morbidity.
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Those patients,
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we don't need to work up these thyroid glands because
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patients very, very rarely will die from thyroid carcinoma.
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They're more likely to die from their
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life limiting comorbidities.
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So this is the outline of the ACR white paper
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that Jenny is the first author on,
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and I recommend you create a macro for
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your reports that describes this workup.
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And then when you find an incidental thyroid
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gland on the CT scan of the neck,
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you just fill in that template macro with the patient's age and
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the size of the nodule to determine whether
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or not to evaluate with thyroid ultrasound.
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The problem with thyroid nodules is
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that based on the imaging features,
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it's very difficult to predict which ones are going to be
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benign and which ones are going to be malignant.
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So here we have two different patients.
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One of these has a malignancy and the
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other has a benign nodule.
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Which is it?
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Benign versus malignant?
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Both have cysts with enhancing nodules.
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Let's look at this case.
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Both of these are solid nodules within the thyroid gland.
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Is this benign or malignant?
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That was benign.
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This one was aspirated and was a malignant mass.
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Can't tell. This is by MRI scan.
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None of the features are diagnostic one way or the other.
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How about this one? We have a mass here,
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and we have a mass here.
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Which one of these two is the benign one?
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Which one is the malignant one?
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This one was malignant in the left side.
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This one a little bit more of a diffuse process than
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you might think of as multinodular goiter.
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But the point is that on CT and MRI,
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there are no really salient features of a thyroid mass
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to determine whether it's benign or malignant.
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Unless it has spread outside the thyroid capsule,
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invaded the trachea or the esophagus,
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or caused recurrent laryngeal nerve paralysis or
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is associated with malignant lymphadenopathy.
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