All of the following are true regarding medullary carcinoma of thyroid except: March 2010
Correct Answer: TSH dependent
Description: Ans. C: TSH dependentMedullary tumors are the third most common of all thyroid cancers (about 5 to 8 percent).Unlike papillary and follicular thyroid cancers which arise from thyroid hormone producing cells, medullary cancer of the thyroid originates from the parafollicular cells (also called C cells) of the thyroid.These C cells make a different hormone called calcitonin.High levels of serum calcitonin and carcinoembryonic antigen are produced by many medullary tumours.Levels falls after resection and rise again with recurrence making it a valuable tumour marker in the follow-up of patients with this diseaseThis cancer has a much lower cure rate than does the "well differentiated" thyroid cancers (papillary and follicular), but cure rates are higher than they are for anaplastic thyroid cancer.Sporadic- Accounts for 80% of all cases of medullary thyroid cancer.They are typically unilateral and there are no associated endocrinopathies (not associated with disease in other endocrine glands.Peak onset 40 - 60. Females outnumber males by 3:2 ratio.One third will present with intractable diarrhea. Diarrhea is caused by increased gastrointestinal secretion and hypermotility due to the hormones secreted by the tumor (calcitonin, prostaglandins, serotonin, or VIP).MEN H-A (Sipple Syndrome). Multiple Endocrine Neoplasia Syndromes are a group of endocrine disorders. Sipple syndrome has bilateral medullary carcinoma or C cell C cell hyperplasia, pheochromocytoma and hyperparathyroidism.This syndrome is inherited and is due to a defect of a gene (DNA) which helps control the normal growth of endocrine tissues.This inherited syndrome is passed on to all children who get the gene (inherited in an autosomal dominant fashion). Males and females are equally affected. Peak incidence of medullary carcinoma in these patients is in the 30's.MEN II-B. This syndrome also has medullary carcinoma and pheochromocytoma, but only rarely will have hyperparathyroidism. Instead these patients have an unusual appearance which is characterized by mucosal ganglioneuromas (tumors in the mouth) and a Marfanoid habitus.Inheritance is autosomal dominant as in MEN II-a, or it can occur sporadically (without being inherited). MEN II-B patients usually get medullary carcinoma in their 30's, and males and females are equally effected.As with MEN II-A, pheochromocytomas must be detected prior to any operation. The idea here is to remove the pheochromocytoma first to remove the risk of severe hypeensive episodes while the thyroid or parathyroid is being operated on.Inherited medullary carcinoma without associated endocrinopathies. This form of medullary carcinoma is the least aggressive. Like other types of thyroid cancers, the peak incidence is between the ages of 40 and 50. Involvement of lymph nodes occurs in 50-60% of cases of MCT and blood-borne metastases are common. They are not TSH dependent and do not take up radioactive iodineTreatment is by total thyroidectomy and either prophylactic or therapeutic resection of the central and bilateral cervical lymph nodes.
Category:
Surgery
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now