One day while admiring yourself in the mirror, you happen to
notice an odd lump in the lower part of your neck. “Gee, that wasn’t there before,” you ponder
to yourself, “or maybe it was.” Your
spouse or significant-other happens to be walking by and stops to look as well,
since obviously you must’ve been thinking aloud or maybe it was the funny
expression in the mirror. Anyway, she
notices it too.
“You oughta get that checked. Could be a tumor. Oh, look at the time! Gotta go--meeting the girls for coffee!” She hustles
out, as your jaw hits the floor.
The thyroid gland is located on the lower part of the
neck. It’s an organ you’ll hardly notice
unless it causes problems, like an unexpected nodule, which is a nonspecific
term for any lump or bump in the gland.
Sometimes the gland has a bunch of nodules causing it to enlarge. Sometimes it becomes large with no nodules. Sometimes patients present not so much with a
visible finding, but with other symptoms such as a sense of choking, difficulty
swallowing, voice changes. Other times there
are nonspecific symptoms such as weight gain or loss, tiredness or anxiety, a
sense of feeling cold or hot when others are comfortably warm (symptoms of hypothyroidism
or hyperthyroidism) which leads to examination of your thyroid gland.
We’ve covered thyroid anatomy and function already. If you need a refresher or you’re hankering
for something fun ‘cause you’ve got nothing better to do on a Saturday night,
then check out The
Thyroid Gland: Where is it and What is it?
Anyway, you’re at the doctor’s office since this lump is
driving you nuts. Your doctor asks a
bunch of questions as doctors always do, makes a few jokes if you’re really
lucky, and then proceeds to feel your neck.
Don’t be alarmed if the doc stands behind you and places their hands
around your neck, just as if you’re going to be choked to death. Relax: a doctor’s a doctor and won’t harm
you, unless you were misbehaving or stiffed the overworked doc on your last bill.
Let’s assume you’re still alive or at least conscious, you
weren’t choked to death and the exam continues.
Now for some real fun. I and most
ENTs want to assess the function of your vocal cords, those two bands of tissue
in your larynx that allows you to converse with friends or complain about your
ginormous deductible or the absurdity of your $8.99 co-pay.
To view the vocal cords and confirm they’re moving normally, the doc will grab your tongue, jam a dental mirror down
your throat and make you gag, all the while forcing you to say something stupid
such as “aaaaa” or “eeeee” which feels impossible to do since your tongue,
covered in gauze, is pulled towards your feet.
Honestly, it’s not that bad and despite the weirdness of it all, most
people tolerate this well, though a few “chunks” were blown my way by a few
highly gag-prone people. Since the
larynx is viewed indirectly with a mirror, this exam is also called an indirect
laryngoscopy.
If an adequate view is not possible with the indirect mirror
exam, we’ll do a nifty procedure with a flexible, fiberoptic scope, called
a nasopharyngoscopy. This looks and sounds more hideous than the reality of the experience and
takes just about a minute.
“Why must you put me through this?” you may ask. Answer: The nerves that move the vocal cords lie
against the backside of the thyroid gland.
Weakness of a cord could be harbinger of malignancy (ie, a cancer)
invading into the nerve.
Sometimes structures around the thyroid can give the
impression be mistaken for a nodule or enlargement. For instance, variations of normal anatomy
such as a generous amount of subcutaneous (below the skin) fat, a prominent
laryngeal cartilage, prominence or tightness of muscles overlying the gland are
examples. Other not-so-normal findings are enlarged
lymph node(s), lipoma (benign fatty tumor), sebaceous cyst (benign cyst found
under the skin), thyroglossal duct cyst, or a variety of other masses.
We mentioned the concept of ultrasound in the last post and
provided a nice picture of a normal study.
Below is one that is not normal.
Ultrasound is great to assess for nodules but also has
another important use: to biopsy a
nodule. One can do a needle biopsy,
which is a sampling of tissue obtained a hollow needle. Ultrasound helps immensely in locating the
nodule in question and guides the doc doing the biopsy (often an interventional
radiologist) for the proper placement the needle.
I try to explain to patients that a thyroid biopsy in the office without ultrasound is
often a “blind pass”—it is difficult to know how deep the needle must be placed
or if something other than the nodule is biopsies. You must pass the needle through skin,
subcutaneous fat, muscle, the thyroid gland itself, before getting to the
nodule. If normal thyroid gland is
sampled away from the nodule, then you can have a false negative
result. Also, there are some good-sized
blood vessels around the thyroid, and you can imagine the bloody mess should
you "biopsy" one of these instead.
The specimen from a needle biopsy is small. The pathologist (a doctor who examines tissue
to determine the nature and cause of disease) then studies the specimen under a
microscope, looking at individual cells to determine a diagnosis. This is difficult to do, which is the reason
pathology is a four-year residency after medical school.
Thyroid cytology (the study of cells, cellular
biology) gets pretty tricky, compared to the cytology of other organs. Usually biopsy will render not only the
diagnosis, but whether it is benign or malignant, the latter being a potential
life-threatening disease. However, there
is one form of thyroid neoplasm (neoplasm means unusual growth) that can
be benign or malignant. This is called a
follicular neoplasm. A variant of this
is a Hurthle cell neoplasm. It is typically
not possible to distinguish the benign versus the malignant form on cytology,
since the cells look the same for both.
The only criteria that makes the tumor malignant are 1. Invasion outside
the capsule of the nodule or 2. Invasion
into a blood vessel. The only way to
determine this is to remove the part of the thyroid gland containing the
nodule(s) in question, and this requires surgery. Then the pathologist can study the entire
gland and see its architecture under the microscope, i.e., how the tumor cells
relate with other cells in the thyroid gland.
Often times people undergo surgery and the final result is a
benign follicular adenoma (adenoma is a benign tumor of a gland) or just a benign goiterous nodule. Benign means non-life-threatening and often
do not need treatment or surgery. Thus, a whole
lot of people have undergone surgery unnecessarily.
However, in the past several years there have been genetic
studies that can be done on thyroid biopsies that show a follicular
neoplasm. One of these tests is called Affirma,
which looks for specific genes that can increase the risk for malignancy. This can add another week or more to the
pathology process (cytology usually takes up to a week). This additional study can then guide whether
to do a thyroid surgery or not.
Nodules are a frequent finding in thyroid glands, more so in
females. The good news is that after the
workup above, the majority of thyroid nodules are benign and need no further
treatment.
We’ll talk more about indications for thyroid surgery in a
future post, so hang tight!
©Randall S. Fong, M.D.
For more topics on medicine, health and the weirdness
of life in general, check out the rest of the blog site at randallfong.blogspot.com
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