Thyroid nodules and thyroid cancer: Pathology review

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Thyroid nodules and thyroid cancer: Pathology review

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Thyroid nodules and thyroid cancer: Pathology review

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A 45-year-old woman is evaluated for voice changes after thyroid surgery. The patient was diagnosed with papillary thyroid cancer and subsequently underwent thyroidectomy. Immediately after the surgery, she noticed some mild voice changes, but the doctor informed her that this is usually transient due to local edema and will likely self-resolve. Currently, the patient describes only mild voice and pitch changes but denies any dysphagia. On physical examination, sensation of the mucosa above the glottis is intact. After evaluation, the doctor suspects an isolated unilateral paralysis of the cricothyroid muscle. Which of the following nerves demonstrated in the picture below was most likely injured during the surgery?


Transcript

On the endocrinology ward, two individuals came in.

Both individuals complained about feeling a lump on their necks, but reports no other symptoms.

The first one is 49 year old Dasha who as a child, lived close to Chernobyl.

The other one is 27 year old Mike, who’s family history involves multiple endocrine neoplasia type 2A.

On exam, they each had a painless mass on their thyroid.

Both people had normal T3, T4, and TSH levels.

They underwent thyroid echography, which showed cold nodules.

Afterwards, fine-needle biopsies were done.

Both individuals had tumors on their thyroids.

First, let’s refresh some info on the thyroid.

The thyroid gland is an endocrine gland located in the neck.

The thyroid gland is made up of thousands of follicles, which are small spheres lined with follicular cells.

Follicular cells convert thyroglobulin, a protein found in follicles, into two iodine-containing hormones, tri-iodo-thyronine or T3, and thyroxine or T4.

Once released from the thyroid gland, these hormones enter the blood and bind to circulating plasma proteins.

Once inside the cell T­4 is mostly converted into T3, at which point it can exert its effect.

T3, among other effects, speeds up the basal metabolic rate, increases cardiac output, stimulates bone resorption and activates the sympathetic nervous system.

The thyroid is also made up of parafollicular or C cells, which are near the follicles.

These cells produce calcitonin, a hormone that lowers blood calcium levels by inhibiting osteoclasts.

Calcitonin also inhibits renal tubular cell reabsorption of calcium, allowing the calcium to be excreted in the urine.

Now, DNA mutations can cause thyroid cells to become cancerous.

For example, a mutation might change a proto-oncogenes like RET and BRAF, which are genes that code for proteins that promote cell growth and proliferation, into oncogenes.

Summary

Thyroid nodules are lumps or growths that form in the thyroid gland, which is located in the neck. Thyroid nodules are relatively common and are often benign. They may cause no symptoms and be discovered incidentally during a physical exam or imaging study, or they may cause symptoms such as difficulty swallowing, hoarseness, or a visible lump in the neck.

Thyroid cancers, on the other hand, are less common than benign thyroid nodules, but the incidence of thyroid cancer has been increasing in recent years. There are several types of thyroid cancer, including papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, and anaplastic thyroid cancer.

The risk factors for thyroid cancer include a family history of thyroid cancer, radiation exposure, and certain genetic syndromes. Symptoms of thyroid cancer can vary, but may include pain in the neck or throat, difficulty swallowing or breathing, and hoarseness. Treatment for thyroid cancer depends on the specific type and stage of the condition. Options may include surgery to remove all or part of the thyroid gland, radiation therapy, and medication to regulate thyroid hormone levels.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Williams Textbook of Endocrinology" Elsevier (2019)
  4. "Ultrasound-Guided Fine-Needle Aspiration of the Thyroid Assessed by Ultrafast Papanicolaou Stain: Data from 1135 Biopsies with a Two- to Six-Year Follow-Up" Thyroid (2001)
  5. "Anaplastic Thyroid Cancer with Uncommon Long-term Survival" Journal of the Chinese Medical Association (2006)
  6. "Diagnosis and Management of Anaplastic Thyroid Cancer" Endocrinology and Metabolism Clinics of North America (2019)
  7. "Thyroid cancer" The Lancet (2016)
  8. "Multiple Endocrine Neoplasia" Surgical Oncology Clinics of North America (2015)
Elsevier

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