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Tumour seeding was only in the incisional biopsy. False negative is problem with fine needle.

Normal Thyroid Structure and Function

  • Patient swallow water --> makes thyroid easier to see.

Thyroid anat.PNG Thyroid histo.PNG Thyroid phys.PNG

T3 = Triiodothyronine; T4 = thyroxine

Investigating the Thyroid

  • Thyroid function tests
    • Radionucleotide, use a geiger counter gadget to see which parts of the thyroid are "cold" and don't take up radionucleotide
  • Thyroid imaging
    • ultrasound
    • thyroid scans
  • FNA of the thyroid

FNAB

  • Simple, quick and safe diagnosis of thyroid lesions
  • Indications
    • Diffuse goitre
    • Solitary dominant nodule
    • Confirmation of malignancy
  • Benefits
    • Decreased diagnostic costs
    • Decreased surgery

Venepuncture is normally done with a 21 gauge needle. Haemolysis occurs if you use too small a needle because it will artefactually increase K+ concentration

Diseases of the thyroid

  • Thyroid neoplasia
  • Thyroid hyperplasia
  • Thyroiditis

Thyroid neoplasms

  • Papillary carcinoma - people our age, increasing in prevalence
  • Follicular neoplasms
    • Thyroid (follicular) adenoma
    • Follicular carcinoma of the thyroid (Note importance of capsular invasion)
  • Medullary carcinoma
  • Anaplastic carcinoma - undifferentiated; very aggressive, in old people; invades great vessels and vital structures in the neck
    • Poor prognosis
  • Other ‐ lymphoma, metastases

Papillary cancers metastasise by lymphatics, medullary ones go in bloodstream. Metastatic thyroid cancer is all curable

Papillary Carcinoma

  • Commonest(75%)
  • Often multiple
  • Predisposed by radiation exposure
  • Spread by lymphatics to cervical nodes
  • Good prognosis - 98% (maybe even above 100% due to increased follow ups). Surgery + chemotherapy.
  • Presents as a lump in the neck, and can cause lumpy cervical lymph nodes

Distinctive cells, a lot of glycogen in the nucleus (hence they're often clear); orphan henny nucleus?, distinctive longitudinal groove in nucleus

Follicular neoplasms

  • Follicular adenoma
    • Absence of capsular invasion
  • Follicular carcinoma
    • Presence of capsular invasion; very good at spreading - especially bone.
    • 10‐20% of thyroid malignancies
    • Single lesion,typically cold
    • Defined by capsule or vessel invasion
    • Spread by bloodstream
    • Treated by surgical resection and radioactive iodine
      • Need to surgically remove all normal thyroid as well
    • Forms a thick collagenous pseudocapsule
    • FNAB shows clusters of epithelial cells; has pale RBCs in background. Distinctive pattern - lots of follicular cells but missing colloid. "Atypical follicular pattern" - cut it out and slice it to check for capsular invasion - if there's capsular invasion it's a cancer. If there isn't any, it's adenoma
    • FNAB can't differentiate between adenoma and carcinoma but it can say 'this is a neoplasm'
    • Salt and pepper chromatin

Medullary carcinoma

  • C cell tumour = parafollicular cell
    • Neuroendocrine tumour
  • Sporadic or familial(20%)
  • Pathology
    • Amyloid in stroma
    • Calcitonin +ve

Multifocal mass, nests of cells (typical of neuroendocrine tumours). Amyloid is between the clusters. Amyloid is not a particular protein, but a method in which proteins form beta pleated sheet, giving them chemical properties (Alzheimer's, diabetes glomerulus, medullary carcinoma of the thyroid, amyloidosis)

Non‐toxic goitre

Goitre = enlargement of thyroid.

  • Synonyms
    • Goitre,multinodular goitre, diffuse goitre,simple hyperplasaia,nodular hyperplasia
      • Diffuse goitre spreads over time to nodular hyperplasia
  • Causes
    • Sporadic
    • Endemic (endemic defined as > 10% of population)
      • Common in Nepal, Tibet, etc where there is low iodine in the soil since high mountains mean the rain washes it out. Developing countries don't put iodine in salt. Live on lowlands near the sea = can't get iodine deficient
  • Clinical
    • Enlarged thyroid (initially diffuse but progressively nodular)
    • Obstructive symptoms - e.g. lift hands above head and face goes red = Pemberton's (obstruct great veins in neck), thoracic inlet symptoms
    • No abnormal thyroid function (euthyroid)
    • FNAB lets you separate out a dysplastic from a neoplastic process
  • Macro
    • Typically multiple colloid nodules, haemorrhage
  • Micro
    • Variable sized follicles, incomplete capsule
    • Chronic inflammation, fibrosis, calcification

Needle in = lump will shrink, so you know it's full of fluid, not tumour --> hyperplastic. Lots of colloid. Result: follicular cells and blood and inflammatory cells and colloid (purple background)

  • Pathologists then tell you it's hyperplasia, avoid unnecessary surgery.
  • Crazy pavement in the background = colloid = don't worry as it's hyperplasia

Graves Disease

Chemosis diplopia and exopthalmus = features of graves disease; as well as affecting the thyroid, it results in mucopolysaccharides behind the eye, and also under the skin. Causes oedema of conjunctiva (chemosis) and affects functioning of extraocular muscles (diplopia)

  • Lid retraction = sympathomimetic effects of thyroxine = most typically seen in hyperthyroidism (any cause), because there are many causes of hyperthyroidism, and Graves is only one of them. (E.g. tumour of pituitary, secondary hyperthyroidism, thyroxine tablets)
  • T3 and T4 are elevated in Graves disease
  • Graves disease is because there are antibodies that act like TSH, they stimulate the TSH receptor, causing increased T3/T4 production, this causes negative feedback on TSH.

Graves path.PNG

Autoimmune attach on the thyroid

  • Goitre – neck swelling
  • Effects of overproduction of thyroxine
    • Thyrotoxicosis
  • Changesin soft tissues
    • Eyes ‐ exophthalmos (weakened perioccular muscles + oedema behind eyeball --> bulging eye), ophthalmoplegia
    • Skin ‐ pretibial myxoedema (NB unrelated: low functioning thyroid = myxoedematous in clinical parlance)
    • Hyperdefecation
    • Affects soft tissues

Thyroiditis

  • Chronic lymphocytic thyroiditis (Hashimoto thyroiditis)
  • Subacute granulomatousthyroiditis (DeQuervain thyroiditis)
  • Other

Hashimoto thyroiditis

  • Clinical
    • Female, 40‐60
    • Family or self history of autoimmune disease
    • Typically hypothyroid
    • Small, firm, “woody” goitre
    • Anti‐thyroid Abs assist diagnosis
  • Pathology
    • Dense lymphoplasmacytic infiltrate
    • Oncocytic change in thyrocytes
    • Increasing fibrosis fibrosis overtime

Hashimoto path.PNG