Practice question answers II Pathology of thyroid

Practice question answers II 

Pathology of thyroid

© Jun Wang, MD, PhD
1. A. An evenly enlarge thyroid gland without abnormal thyroid function is most consistent with simple goiter, most commonly caused by iodine deficiency. Follicular adenoma and papillary thyroid carcinoma have discrete growth. Graves disease has presentations of thyrotoxicosis. Hashimoto thyroiditis is characterized by thyroitoxicosis at early phase and hypothyroidism at later phase.  

2. C. Endemic goiter is most commonly caused by iodine deficiency. Autoimmune process is associated with Graves disease and Hashimoto thyroiditis. Bacterial infection is seen in acute thyroiditis.  Ret mutation is seen in medullary carcinoma and papillary thyroid carcinoma. Viral infection may be associated with granulomatous thyroiditis (de Quervain's thyroiditis).

3. B. Cycling changes of follicular hypertrophy due to TSH effects and involution is thought to cause thyroid enlargement in patients with goiter. Activating antibodies against TSH receptor is seen in Graves disease. Proliferation of parafollicular cells are seen in C cell hyperplasia and medullary carcinoma. Autoantibodies against thyroid peroxidase or thyroglobulin are seen in Hashimoto thyroiditis. In addition, follicular destruction is NOT a feature of goiter.

4. C. Unevenly benign enlargement of thyroid with nodular pattern is multinodular goiter. Follicular adenoma has packed small follicles, usually similar sizes. Graves disease has presentations of thyrotoxicosis. Squamous cell carcinoma has typical features of squamous differentiation, such as intercellular bridges and/or squamous pearls. Thyroglossal duct cyst may contain ectopic thyroid tissue, but is typically a cyst lined by with stratified squamous or respiratory type epithelium.

5. E. Thyrotoxicosis in a background of multinodular goiter is most likely toxic goiter (Plummer syndrome). Granulomatous thyroiditis is may have transient thyrotoxicosis, and it has follicular destruction and granulomatous changes, such as multinucleated giant cells, in the absence of microorganism. Follicular cell activation as characterized by columnar shape with finger like crowded growth, as well as thin pale colloid are seen in Graves disease, but these changes are diffuse, not focal, in Graves disease. Hashimoto thyroiditis is characterized by follicular destruction in a background of diffuse polyclonal lymphoid infiltrate, with or without lymphoid follicle formation. Follicular carcinoma has packed small follicles with vascular or capsular invasion.

6. A. Well-formed nodular growth of packed small follicles with normal appearing follicular cells is follicular adenoma, if no invasion can be seen. Follicular adenoma can be functional with presentations of thyrotoxicosis.   Follicular carcinoma has packed small follicles with vascular or capsular invasion. Graves disease is characterized by proliferation of follicular cells, thin pale colloid with vacuoles adjacent to follicular cells, with intact follicular structure.  Hashimoto thyroiditis is characterized by follicular destruction in a background of diffuse polyclonal lymphoid infiltrate, with or without lymphoid follicle formation. Papillary thyroid carcinoma, including follicular variant, is diagnosed based on typical nuclear features, such as enlarged nuclei, washed out chromatin, nuclear grooves or inclusion.

7. D. Activating mutation of TSH receptors is seen in many cases of toxic follicular adenoma. Activating antibodies against TSH receptor is seen in Graves disease. Destruction of follicles may cause elevated thyroid hormone, as in Hashimoto thyroiditis and granulomatous thyroiditis. Negative feed back to pituitary TSH producing cells will lead to higher, NOT lower, levels of TSH.

8. A. See discussion in question 6.

9. E. See discussion in question 6.

10. D. Papillary thyroid carcinoma is most commonly associated with RET-PTC translocation. Menin 1 mutation is seen in MEN 1, characterized by tumors of parathyroid glands, the enteropancreatic endocrine cells, the anterior pituitary gland, and the skin. PAX8 and PTEN mutation is seen in various tumors, including follicular carcinoma of thyroid. TSH receptor mutation may be seen in toxic follicular adenoma.

11. C. One of the most characterized feature for papillary thyroid carcinoma is its tendency to be multifocal and bilateral. Regression with iodine supplementation may be seen in patient with iodine deficiency associated goiter.

12. E. Clear cell type renal cell carcinoma is characterized by islands of cells with clear cytoplasma and fine vasculature, not nuclear inclusion or grooves. Also see discussion in question 6.

13. D. See discussion in question 10.

14. E. Total thyroidectomy is the appropriate management for papillary thyroid carcinoma.

15. C. Follicular carcinoma has packed small follicles with vascular or capsular invasion. Anaplastic thyroid carcinoma is an undifferentiated malignant tumor with markedly atypical tumor cells. Also see discussion of question 6.

16. C. p53 mutation is usually seen high grade malignancies, including Anaplastic thyroid carcinoma.It is usually not seen in follicular carcinoma of thyroid. Also see discussion is question 10.

17. D. A thyroid tumor with eccentric nuclei, punctuate chromatin, and amyloid deposit, but has with no follicular differentiation is likely to be medullary thyroid carcinoma. Anaplastic thyroid carcinoma is an undifferentiated malignant tumor with markedly atypical tumor cells. Also see discussion of question 6.

18. D. Activating RET mutation can be seen in medullary thyroid carcinoma. Also see discussion is question 10.

19. D. Medullary thyroid carcinoma derived for C cells and produces calcitonin. Autoantibodies against thyroid peroxidase or thyroglobulin, and inhibitory antibodies against TSH receptor are seen in Hashimoto thyroiditis. Hypercalcemia and elevated parathyroid hormone are seen in hyperparathyroidism.

20. A. Anaplastic thyroid carcinoma is an undifferentiated malignant tumor with markedly atypical tumor cells. Follicular carcinoma has packed small follicles with vascular or capsular invasion. Hodgkin lymphoma has Reed-Sternberg or LP cells in a background of lymphocytes, and is negative for cytokeratin. Medullary thyroid carcinoma has eccentric nuclei, punctuate chromatin, and amyloid deposit, and usually does not have marked pleomorphism. Undifferentiated pleomorphic sarcoma is a diagnosis of exclusion, and is negative for cytokeratin.


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