Surgical Endocrinology

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Text of Surgical Endocrinology

  • 1. Surgical Endocrinology University of Virginia Clinical Clerkship in Surgery Peter I. Ellman M.D.

2. Plan for Talk

  • Review the objectives as outlined by the Lawrence text.
  • Discuss the anatomy, physiology, pathophysiology, diagnosis and treatment of thyroid, parathyroid and adrenal gland disorders.
  • Discuss the MEN syndromes.

3. Objectives for the Thyroid Gland

  • Discuss the evaluation and differential dx of a patient with a thyroid nodule.
  • List the different types of thyroid cancer, their cell types of origin, and the appropriate theraputic strategy for each.
  • Major risk factors for carcinoma of the thyroid gland and prognostic variables that dictate therapy.
  • SX of Hyperthyroidism, DDX and TX

4. Objectives for the Parathyroid Glands

  • Understand the role of the parathyroid glands in the physiology of calcium hemostasis.
  • List the causes, symptoms, and signs of hypercalcemia.
  • Know the difference between 1, 2,4 hyperparathyroidism.
  • Discuss the evaluation and ddx of a paitent with hypercalcemia.
  • Understand the management of acute and severe hypercalcemia.
  • Surgical indications for hyperparathyroidism
  • Complications of parathyroid surgery.

5. Objectives for the Adrenal Glands

  • Describe the clinical features of Cushings syndrome and discuss how lesions in the pituitary, adrenal cortex and extraadrenal sites are distinguished diagnostically.
  • Med and surg mgmt of patients with adrenal adenoma, pituitary adenoma causing adrenal hyperplasia, and with ACTH producing neoplasm.
  • Path, clinical features, lab findings, W/U, mgmt. of pt with 1 aldosteronism.
  • Discuss pheochromocytoma, signs and symptoms, W/U, mgmt.
  • Discuss adrenal cortical carcinoma, assoicated signs and symptoms, W/U managment.
  • Mgmt. and evaluation of incidentally discovered adrenal mass.
  • Causes of adrenal insufficiency in surgical setting, as well as clinical and laboratory findings (RECENT JAMA ARTICLE)

6. Thyroid Anatomy

  • Two lobes in neck, connected by isthmus at second tracheal ring.
  • Embryologic origin at site of foramen cecum on tonguemigrates ventral to the hyoid bone why people get thyroglossal duct cyst.
  • Arerial supply2 : Superior thyroid artery via the external carotid and Inferior thyroid artery via the Thyrocervical trunk (off the subclavian).
  • Venous drainage3: through the superior, middle and inferior thryoid veins.

7. Thyroid Physiology

  • Two groups of hormone producing cells
    • 1: Follicular cells produce, store and release T 4and T 3
    • 2: Parafollicular cells secrete calcitonin.

8. Follicular cells

  • Capture iodide from the circulation and concentrate it and then oxidize it (organification, occuring in the apical membranes of the cells)
  • Tyrosine residues of thyrogolbulin are then iodinated by oxidized iodides, forming monoiodotyrosine and diiodotyrosine which then couple to form T 4and T 3 -which is then stored.
  • When thyroid stimulating hormone (TSH) stimulates the thyroid, the iodinated thyroglobulin then is taken into the cell and is hydrolized to T 4and T 3 -which is then released into the circulation.

9. TSH

  • Besides stimulating the release of T3 and T4, TSH can stimulate the cell to increase production of thyroid hormones.
  • TSH production is stimulated by Thyrotropin-releasing hormone (TRH) which is secretedby the hypothalamus. This intern is controlled by a feedback mechanism. Increased T3 and T4 have a negative feedback mechanism on TRH as well as TSH

10. The parafollicular (aka C cells)

  • Secrete calcitonin which is stimulated by high serum calcium levels, which inhibits osteoclast activity, which in turn decreased calcium levels.
  • Total absence of these cells produces no demonstrable negative physiologic effect!

11. Objective T1:W/U of Thyroid Nodule

  • Always a thorough H & P (remember for oral exam).
    • Hx of irradiation to the head or neck?
    • Family history of MEN syndrome (will get to this later)
    • Carefully palpate the thyroid and regional lymph nodes.
    • How long has nodule been present? Any associated pain, hoarseness, dysphagia, dyspnea, or hemoptysis?

12. Objective T1:W/U of Thyroid Nodule

  • On physical exam:
    • Nodule shouldbe carefully examined to assess size, consitency, extension and fixation. Single or multiple?
    • Is there cervical lymphadenopathy?
    • Is there a rapid pulse, tremor, exopthalmos?
    • Direct laryngoscopy is important in preoperative evaluation to assess for vocal cord paralysis.

13. DDX of thyroid nodule

  • Benign
    • Toxic thyroid adenoma
    • Cyst
    • Papillary adenoma
    • Follicular adenoma (most common adenoma)
      • Colloid (macrofollicular)
      • Fetal (microfollicular)
      • Embryonal
    • Hrthle cell adenoma
  • Malignant
    • Papillary CA
    • Follicular CA
    • Hrthle Cell CA
    • Medullary CA
    • Anaplastic CA
    • Thyroid Lymphoma
    • Metastatic Carcinoma to the Throid Gland.

14. FNA

  • Fine needle aspiration is the single most important study in evaluating a thyroid mass.
    • Only 3% of patients with a benign dx on FNA have thryoid cancer, and 85% of nodules identified as malignant on FNA are cancers at resection.
      • 68% to 98% sensitive and 56% to 100% specific.
      • Approx 75% areclassified as benign, 25% as suspicious and 5% as malignant.
  • Follow patients with benign dx closely
  • Follicular adenomas cannot be distinguished from follicular carcinoma by FNA and warrants a surgical exploration--most likely total thyroidectomy.
    • do not do frozen section! It has been shown to be notoriously inaccurate!)

15. Other imaging modalities

  • Not required for the routine evaluation of the vast majority of thyroid nodules.
  • It is important to try and avoid the use of iondinated contrast materials preperatively.
    • This can impair postoperative tx.
  • Hot vs. Cold nodules.
    • A technicium thyroid scan may show a cold or hypofunctioning nodule. While it is c/w cancer, it could also be benign solid or cystic nodule that could be diagnosed with or even treated with FNA.

16. Use of ultrasound

  • Good for determining the size, number and location of thyroid nodules accurately.
  • Questionable use as a screening tool. Can increase the rate of finding incidentalomas.

17. Objective T2: List7Thyroid Carcinomas, Cell Types, and Tx.

  • Papillary CA
  • Follicular CA
  • Hrthle Cell CA
  • Medullary CA
  • Anaplastic CA
  • Thyroid Lymphoma
  • Metastatic Carcinoma to the Throid Gland.

18. Papillary CA

  • Divided into the papillary, mixed papillary/follicular and follicular variant of papillary.
  • Most Common Thyroid Malignancies!
  • Arises fromFollicular Cells
    • Histologically associated with fibrosis, calicifications, squamous metaplasia, psammoma bodies, lymphatic invasion.

19. Papillary CA TX

  • Tx is somewhat controversial. At the very least pt needs ipsilateral lobectomy and isthmusectomy. Some surgeons recommend total thyroidectomy. It is important to know that you dont just take out the nodule!
  • LND for clinically significant nodal disease.
  • Surgery is followed by scanning with radioactive iodine to detect residual normal thyroid tissue as well as metastatic disease (lungs and bones).

20. Follicular CA- Overview

  • Increased in regions of the world where iodine is deficient.
  • Dx of malignancy requires that either vascular or capsular invasion by tumor be demonstrated.
  • Again, FNA and Frozen Section cannot be trusted. Dx is deferred pending histologic review.

21. Follicular CACell origins

  • Come from follicular cells (not surprising)
  • On histologic exam there is a pauc