Practice question answers Pathology of thyroid I

Practice question answers

Pathology of thyroid I

© Jun Wang, MD, PhD

1. E. This patient has features of hypothyroidism, and thyroid function test should be included. Bone marrow aspiration/biopsy may be indicated for anemia or other hematopoietic disorders. Head CT is for intracranial abnormalities that usually have more neurological abnormalities. Bilateral deep vein thrombosis may cause pedal edema, but usually not associated other systemic presentations.

2. D. Abnormal TSH levels are the most sensitive test for thyroid functions. A high level of TSH is seen in hypothyroidism, and suppressed TSH is seen in thyrotoxicosis.

3. D. Follicular destruction in a background of diffuse polyclonal lymphoid infiltrate, with or without lymphoid follicle formations, is consistent with Hashimoto thyroiditis. Diffuse large B cell lymphoma has diffuse lymphocytic infiltration with marked cytological atypia. Follicular lymphoma is a monoclonal lymphoid proliferation. Graves disease does not have follicular destruction. Papillary thyroid carcinoma is diagnosed based on typical nuclear features, such as enlarged nuclei, washed out chromatin, nuclear grooves or inclusion.

4. C. Hashimoto thyroiditis is an autoimmune process, most commonly with autoantibodies against thyroid peroxidase or thyroglobulin. Activated T cells cross reacting with TSH receptor and activating autoantibodies against TSH receptor is seen in Graves disease. Reduced levels of TRH in hypothyroidism is seen in hypothalamus failure and should not have thyroid presentations of lymphocytic infiltrating, etc. Reduced levels of TSH is seen in thyrotoxicosis, not hypothyroidism.

5. A. An infant with coarse skin, poor neurological development and failure to thrive, as well as physical findings of large protruding tongue is likely neonatal hypothyroidism. It is confirmed by high TSH and low T4. Granulomatous thyroiditis usually presents with thyroid pain, fever and transient hyperthyroidism. Graves disease, Hashimoto thyroiditis, and subacute lymphocytic thyroiditis are rare in infant, and usually do not presents with developmental defects.

6. A. Anatomic defect is the most common cause of infant hypothyroidism. Activating antibodies against TSH receptor is seen in Graves disease. Autoantibodies against thyroid peroxidase or thyroglobulin are seen in Hashimoto thyroiditis. Reduced levels of TRH in hypothyroidism seen in hypothalamus failure and is very rare. Reduced levels of TSH is seen in thyrotoxicosis, NOT hypothyroidism.

7. E. This patient has presentations suggestive of thyrotoxicosis, and TSH is the most sensitive test for abnormal thyroid functions. Higher levels of adrenalin is associated with hypertension. Higher levels of cortisol will cause Cushing syndrome. Parathyroid hormone will elevate serum calcium, while calcitonin reduces serum calcium. None of these will cause thyrotoxicosis.

8. B. Thyrotoxicosis with proptosis is highly suggestive of Graves disease, since proptosis is not seen in other types of thyrotoxicosis, such as early phase of Hashimoto thyroiditis. Simple goiter and papillary thyroid carcinoma are usually euthyroid, and the later has discrete thyroid mass. TSH producing tumor should have higher level of TSH.

9. A. 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. Ectopic thyroid tissue, as seen in struma ovarii or thyroglossal duct cyst, may cause thyrotoxicosis, but not proptosis. Hyperfunctioning thyroid nodules, as seen in follicular thyroid adenoma, or toxic goiter, usually has discrete thyroid nodules. Iodine deficiency is associated with goiter and hypothyroidism, not Graves disease.

10. E. Proptosis seen in Graves disease is caused by increased volume of retroorbital connective tissue, as a result of cross action with TSH receptors by activated T cells.

11. B. Proliferation of follicular cells, thin pale colloid with vacuoles adjacent to follicular cells, with intact follicular structure, is seen in Graves disease. Family history of hyperlipidemia raises the concern of heart attack, but usually heart attack does not have presentations of enlarged thyroid and lid-lag, etc, as seen in thyrotoxicosis. Hashimoto thyroiditis is characterized by follicular destruction in a background of diffuse polyclonal lymphoid infiltrate, with or without lymphoid follicle formation. Multinodular goiter usually has flat to low cuboid follicular cells without proliferation. Papillary thyroid carcinoma is diagnosed based on typical nuclear features, such as enlarged nuclei, washed out chromatin, nuclear grooves or inclusion.

12. E. Abnormal TSH levels are the most sensitive test for thyroid functions.

13. B. Staring gaze seen in thyrotoxicosis is caused by hyperactivity of superior tarsal muscle due to increased sympathetic tone. Facial nerve paralysis will have abnormalities in other facial muscles. Myxedematous changes, or proliferation of connectives tissue should be identified through physical examination, but they are not associated with movement of eyelid.

14. E. Thyroid tissue in ovary is seen in struma ovarii, a type of mature teratoma. Goiter, follicular carcinoma, Graves disease and Hashimoto thyroiditis all have abnormal thyroid gland findings.

15. E. Abnormal TSH levels are the most sensitive test for thyroid functions. Elevated AFP is seen in Yolk sac tumor. CA125 is usually elevated in serous ovarian carcinoma. CEA is usually elevated in mucinous ovarian carcinoma. hCG is elevated in any tumor with trophoblast components.

16. E. Acute exaggeration of thyrotoxicosis is compatible with thyroid storm, a life threatening emergency.

17. C. Although the patient presents with depression, a sign usually seen in hypothyroidism, the presence of weight loss and atrial fibrillation is more suggestive of apathetic hyperthyroidism, especially in elder population. Symptomatic thyrotoxicosis usually has low TSH and high T3 or T4.

18. A. See discussion in question 17.

19. B. Granulomatous thyroiditis is most common cause of thyroid pain, and usually presents with transient thyrotoxicosis. Presence of follicular destruction, granulomatous changes, such as multinucleated giant cells, in the absence of microorganism, is characteristic for granulomatous thyroiditis. Acute thyroiditis is usually bacterial infection with neutrophilic infiltration. Graves disease and Hashimoto thyroiditis do not have granulomatous changes. Any adenocarcinoma should be certain degree of glandular differentiation, such as irregular glands.

20. C. See discussion of question 17.

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