Thyroid nodules and neoplasms

Thyroid nodules and neoplasms

• Upon completion of this lecture the students will be able to:

• Understand the concept of diffuse and multinodular goiter and solitary nodule.

• Recognize the difference between adenoma and carcinomas.

• Describe the pathological findings in adenoma and the different types of thyroid carcinomas.

Thyroid Neoplsms

• Solitary nodules : neoplastic• Nodules in younger patients : neoplastic• Nodules in males : neoplastic• A history of radiation : neoplastic• Nodules radioactive iodine (hot nodules) :

benign

Adenomas

• Adenomas of the thyroid are typically discrete, solitary masses. (follicular adenomas)

• Degree of follicle formation and the colloid content of the follicles:

• Simple colloid adenomas (macrofollicular adenomas)

• A common form recapitulate stages in the embryogenesis of the normal thyroid (fetal or microfollicular, embryonal or trabecular).

Adenoma

Thyroid Adenoma

Carcinomas

• Carcinomas of the thyroid : 1.5%• Papillary carcinoma (75% to 85% of cases)• Follicular carcinoma (10% to 20% of cases)• Medullary carcinoma (5% of cases)• Anaplastic carcinoma (<5% of cases)

Carcinomas • Follicular Thyroid Carcinomas: mutations in the RAS family of

oncogenes (HRAS, NRAS, and KRAS) NRAS mutations being the most common.

• Papillary Thyroid Carcinomas. rearrangements of the tyrosine kinase receptors RET or NTRK1

• Medullary Thyroid Carcinomas: Familial medullary thyroid carcinomas occur in multiple endocrine neoplasia type 2 (MEN-2) RET protooncogene mutation

• Anaplastic Carcinomas: Inactivating point mutations in the p53 tumor suppressor gene are rare in well-differentiated thyroid carcinomas but common in anaplastic tumors.

• Environmental Factors. The major risk factor predisposing to thyroid cancer is exposure to ionizing radiation

Papillary Carcinomas

• Papillary structures• Orphan Annie nuclei• Psammoma bodies• Pseudoinclusions• Grooved nuclei

Papillary Carcinomas

• Tall cell variant• Hyalinizingtrabecular tumors ( ret/PTC gene

rearrangement)• Follicular • Encapsulated• Diffuse sclerosing

Papillary Carcinomas

Follicular Carcinomas

• Minimally invasive• Widely invasive

Follicular Carcinomas

Follicular Carcinomas

Medullary Carcinomas

• Medullary carcinomas of the thyroid are neuroendocrineneoplasms derived from the parafollicular cells, or C cells, of the thyroid.

Medullary Carcinomas

• Polygonal to spindle cells• Amyloid deposition• Bilaterality• Multicentricity• Necrosis • Hemorrhage

Medullary Carcinomas

Anaplastic Carcinomas

• Anaplastic carcinomas of the thyroid are undifferentiated tumors of the thyroid follicular epithelium.

• Arising from a more differentiated carcinoma (papillary)

• Lethal (100%)• Older age group > 65year

Anaplastic Carcinomas

• Highly anaplastic cells:• (1) large, pleomorphicgiant cells, including

occasional osteoclast-like multinucleate giant cells

• (2) spindle cells with a sarcomatous appearance

• (3) mixed spindle and giant cells• (4) small cells

Anaplastic Carcinomas

Conclusion

• Homework:• MEN