Junior Surgery Lecture
Salivary & Thyroid
This lecture is on salivary
gland diseases and thyroid diseases.
This an overview, but will touch on the topics you’ll need to know for
the exam.
Slide 1: We’ll start
with salivary gland diseases. The
salivary gland functions are to maintain oral and dental hygiene, prepare food
for mastication, taste and deglutition, and begin carbohydrate digestion with
amylase. In addition, they indirectly
regulate body hydration because if you’re dehydrated, you’ll likely have a dry
mouth, and you’ll want to drink more.
Slide 2: This is a
cartoon of the right side of the mandible, looking from inside the mouth. This is the cut edge of the mandible. This is the sublingual gland; ducts of
Rivinus; Wharton’s duct; submandibular gland (aka submaxillary gland). Note in this cartoon that the mylohyoid
separates the superficial and deep lobes of the submandibular gland.
Slide 3: This
cartoon shows the facial nerve coming out of the stylomastoid foramen, just
below the auditory canal. The facial
nerve separates the parotid gland into the superficial and deep lobes.
Slide 4: This
cartoon shows the facial nerve after removal of the superficial and deep lobes
of the parotid. A point to emphasize
here is that facial weakness may be caused by a parotid malignancy.
Slide 5: The
most common symptom of salivary gland disease is swelling of the gland. Rapid swelling typically occurs with
inflammatory disorders, while a slower onset of swelling occurs with neoplasms. Bilateral swelling is more typical of
infectious of autoimmune disorders, but may also occur with some tumors.
Slide 6: The diagnosis
of salivary gland disorders begins with a complete history and physical
examination. Plain x-rays can detect up
to 90% of submandibular stones, but only 105 of parotid stones are
radiopaque. A dental occlusal view is
the best view to see a submandibular stone.
Contrast sialography can identify radiolucent stones. Some salivary gland neoplasms take up the
radionucleotide tracer, Technecium 99.
This tracer concentrates in Warthin’s tumor, also known as papillary
cystadenoma lymphomatosum, as well as in oncocytomas, because these tumors have
lots of mitochondria, which is where the Technecium 99 concentrates. Pleomorphic adenoma, which is the most
common parotid neoplasm, does not take Technecium 99. CR or MRI is obtained for deep tumors or if malignancy is
suspected. Angiography is rarely
useful. A fine needle aspiration, or
FNA, is commonly obtained for salivary gland masses. FNA is the best initial management for almost all masses in the
parotid area. An open biopsy of
salivary glands is done carefully because of nearby nerves. A parotid gland open biopsy is performed by
first identifying the facial nerve, and then removing the overlying superficial
parotid gland. This is called a
superficial parotidectomy. A
submandibular open biopsy if performed as an excision of the gland, with
identification and preservation of the lingual nerve.
Slide 7: Infection of
the salivary glands may be either viral or bacterial in origin. Viral sialadenitis may be caused by
Coxsackie virus, echovirus, CMV or mumps virus. Mumps virus is the most common cause of viral salivary gland
infection. It causes acute,
nonsuppurative enlargement of both parotid glands with low-grade fever, malaise
and anorexia. Its course is usually
mild.
Slide 8: This is in
contrast to bacterial sialadenitis, also known as suppurative sialadenitis or
surgical parotitis. It occurs in
dehydrated, debilitated patients. There
is a rapid onset of swelling and fever, with erythema and warmth over the
affected gland. You can sometimes see
pus coming from the duct. Staph. Aureus
is the most common organism. Treatment
is IV fluids, augmented penicillins and sialogogues, and possibly surgical
drainage.
Slide 9: This is
bacterial sialadenitis of the submandibular gland.
Slide 10:
Sialolithiasis is stones in the salivary gland or duct. Ninety percent of salivary stones occur in
the submandibular gland, and 10% occur in the parotid gland. Seventy to 90% of all stones are radiopaque;
that is, they are white on plain films.
However, only 10% of parotid stones are radiopaque. Sialolithiasis is associated with sudden
pain or swelling with eating, relieved by a sudden gush of fluid into the
mouth. Sialolithiasis may predispose
the patient to repeated episodes of bacterial sialadenitis.
Slide 11: Neoplasms of
the salivary glands usually occur in the major salivary glands, with 80%
occurring in the parotids, and almost 20% occurring in the submandibular
glands. Parotid tumors are benign 80%
of the time, and malignant 20%.
One-half of submandibular tumors are malignant. Eighty percent of salivary gland tumors are
malignant. Minor salivary glands are
located in the lips buccal mucosa and palate.
The most common site of minor salivary glands is the hard palate.
Slide 12: Benign
epithelial neoplasms include pleomorphic adenoma, which is also known as mixed
tumor. It is the most common benign
salivary gland tumor. Warthin’s tumor,
also known as papillary cystadenoma lymphomatosum, is common in elderly men,
and can be bilateral. Monomorphic
adenoma is another benign neoplasm of the salivary glands. These tumors present as discrete painless,
slowly enlarging masses, usually in the superficial lobe of the parotid
gland. There is no facial nerve
weakness. Treatment is superficial
parotidectomy.
Slide 13: This is
pleomorphic adenoma. Again, the most
common benign salivary tumor in adulthood.
Slide 14: This is
Warthin’s tumor, again usually seen in elderly men.
Slide 15: And this is
bilateral Warthin’s, which can sometimes happen.
Slide 16:
Mucoepidermoid carcinoma is the most common malignant neoplasm of the
parotid gland. Adenoid cystic carcinoma
is the most common malignant tumor of the submandibular gland, also called the
submaxillary gland. Adenoid cystic
carcinoma is particularly nasty in that it has a very high tendency to invade
and travel along nerves, making curative resections very difficult. Acinic cell carcinoma and these others are
less common salivary gland malignancies.
Slide 17: The lesion
with enlarged vessels in the overlying skin is adenoid cystic carcinoma. It’s not unusual to have to cut into the
mastoid bone to remove the invaded facial nerve in these cases.
Slide 18: This is
mucoepidermoid carcinoma, often hard to distinguish from benign tumor without
pathologic examination.
Slide 19: Studies have
been done on salivary malignancies. The
main point here is that facial weakness is a sign of malignancy, and it’s also
a sign of poor long-term survival.
Slide 20: Nonepithelial
neoplasms of the salivary glands are uncommon in adults. They are usually located in the parotid
gland, and can be any tumor of mesenchymal origin.
Slide 21: In children,
salivary gland tumors are rare.
Non-epithelial tumors are the most common in children. Specifically, the most common salivary gland
tumor in children is hemangioma. The
most common malignant tumor is mucoepidermoid carcinoma, the same as in adults.
Slide 22: This is a
parotid hemangioma. They will usually
resolve spontaneously.
Slide 23 – 27: The thyroid
gland is located just below the cricoid cartilage in the anterior part of the
neck. The arterial blood supply is from
the superior thyroid artery, which is the first branch off the external carotid
artery, and the inferior thyroid artery, which is a branch of the thyrocervical
trunk. There is a superior, inferior
and a middle thyroid vein of each side.
The recurrent laryngeal nerve courses just deep and lateral to the
thyroid gland. As you know, it supplies
the only muscles that open the vocal cords, so these nerves need to be
identified and preserved in thyroid surgery.
Slide 24: The most
common thyroid abnormality that we see patients for is the thyroid nodule. Nodules occur in 4% of the population, with
10, 000 nodules diagnosed each year.
Only 1-10% of these nodules are malignant, and malignancies are slightly
more prevalent in females.
Slides 28 & 29: As
with most workups, the diagnostic workup for thyroid nodules begins with a
complete history and physical exam.
Prior radiation exposure or family history of thyroid malignancy point
towards a nodule being malignant. The
vocal cords should be evaluated, because vocal cord weakness or paralysis would
also point towards a nodule being malignant.
Thyroid function tests are less helpful in distinguishing a benign from
malignant nodule. Radionucleotide scanning
is done to differentiate hot from cold nodules. Hot nodules are those that take up increased amounts of the
radionucleotide. Cold nodules are more
likely to be malignant. A cold nodule
is the most important finding on a thyroid scan. Ultrasound distinguishes cystic from solid nodules. Fine needle aspiration is performed on most
palpable nodules, and can identify certain malignancies.
Slide 30: Papillary
carcinoma is the most common thyroid malignancy. Most patients are asymptomatic.
The tumor is slow growing, and many patients will present with cervical
lymph node metastases.
Slide 31: Follicular
carcinoma account for up to one quarter of thyroid malignancies. It is also slow growing and usually
asymptomatic. It usually presents in
the 5th and 6th decades of life, is more common in
females, and may spread both via lymphatics and in the blood.
Slide 32: Medullary
carcinoma of the thyroid arises from parafollicular of C-cells. It may be associated with multiple endocrine
neoplasia syndromes, specifically MEN II.
This lesion is often detected by elevated calcitonin levels.
Slide 33: Anaplastic
carcinoma occurs in 4-8% of thyroid malignancies. It grows rapidly, invades adjacent tissues, and often presents
with vocal cord paralysis from recurrent laryngeal nerve involvement. It has a very poor prognosis.
Slide 34: This graph
shows the survival curve for anaplastic thyroid carcinoma. Pretty pitiful.
Slide 35: Treatment for thyroid carcinoma is total or subtotal thyroidectomy with neck dissection if lymph nodes are palpated in the neck.
Lymphoma of thyroid is rare,
but does occur. It is treated like
lymphoma elsewhere, with chemotherapy or radiation. Lymphoma is sometimes seen in patients who have had Hashimoto’s
thyroiditis.