Thyroid Cancer: Adenoma, Papillary, Follicular, Medullary, Anaplastic for USMLE Step 1

Thyroid Cancers for USMLE Step 1:
In this video we will be looking at Adenoma Thyroid Cancer. Papillary Thyroid Cancer. Follicular Thyroid Cancer, Medullary Thyroid Cancer and finally anaplastic Thyroid Cancer. This will include the pathognesis of the thyroid cancers, histology of the thyroid cancers, symptoms of thyroid cancer, investigations and treatment of thyroid cancers as well as prognosis of thyroid cancers.

THYROID ADENOMA (benign)
Nonfunction is more common
Functional - much less likely to be benign
10% move on to become follicular carcinoma
Pathogenesis - mutation in TSHR signaling system. This is where 50% of our toxic adenomas come from. Also mutation in alpha subunit of Gs leads to constant activation

SYMPTOMS of Thyroid Cacer
Unilateral painless mass developing over a period of time. If non-functional then it is asymptomatic until mass effect. If functional the symptomatic. Therefore thyroid adenoma is difficult to detect

PAPILLARY Thyroid Cancer (Malignant)
Associated with radiation.
Papillary carcinoma is solitary, capsulated, infilrative or multiple, So Papillary carcinoma can have many different types. Asymptomatic nodule in the neck which moves freely when swsallowing. Disphagia and dyspnea.

Histology of Thyroid Cancer - psamomma bodies (also found in meningioma, and ovarian cancer). Orphan Annie Nucleus - Nucleus looks empty.

Treatment of Papillary Thyroid Cancer
Thyroidectomy, Radioactive Iodine which will kill a lot of tumor cells. Supression therapy which will increase T3 and TSH as well. When it mestastasize to the lymph node there is not change in prognosis.

FOLLICULAR THYROID CANCER
Etiology of Follicuar thyroid cancer is radiation. You must look for invasion in order to stage. It can be encapsulated or infiltrative. Lymph node metastasis is uncommon as it usually goes to the lung or bone.

MEDULLARY THYROID CANCER
Histology - tumor of the parafolicular cells which make calcitonin. The sporadic type (80%) and familial type (20%) Familial type of medular thyroid cancer is more common.
Pathogenesis is related to RET oncogene and therefore is associated with MEN2A and MEN 2B which are endocrine cancrees that are associated with other types of cancers. In the video I have drawn a diagram which helps memorize the differences. I hope it helps remember it better.
Complications - cushings

ANAPLASTIC THYROID CANCER
This is the most serious cancer. Elderly women with multnodular goiters and follicular thyroid cancer. Prognosis for anaplastic thyroid cancer is 100% fatal and common cause of death is tracheal compression

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  Thyroid Cancer