Classification of thyroid diseases

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Classification of thyroid diseases

• Enlargement of the gland
• Goiters
• Tumors
• Hyperthyroidism
• Graves disease
• Toxic multinodular goiter
• Toxic adenoma
• Hypothyroidism
• Hashimoto thyroiditis
• Suabcute thyroiditis
• Riedel thyroiditis
• Congenital Cretinism

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Enlargement of the gland

• Goiters
• Non toxic goiter
• Diffuse non toxic goiter
• Multinodular goiter
• Thyroid cancer

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Goiters

• Goiter an overgrown of the thyroid gland
  usually seen as a swelling in the neck.
• The swelling may be linked to hyperthyroidism,
  hypothyroidism or normal levels of thyroid
  function
• There are many types of goiters
• Non toxic goiter
• Diffuse goiters
• Multinodular non toxic goiters
• Multinodular toxic goiter included under
  hyperthyroidism

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A. Non toxic goiters

• Non toxic goiters are also called simple, colloid
  or multinodular goiter.
• It refers to an enlargement of the thyroid that
  is NOT associated with functional, inflammatory
  or neoplastic alterations ? therefore, patients
  are euthyroid
• More common in females
• Diffuse form of goiters presents mostly in
  adolescents and pregnancy
• Multinodular form presents in persons older than
  50 years of age.

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A. Non toxic goiters

• Pathogenesis
• Patients are thought to have a subtle impairment
  of iodine utilization and to respond in an
  exaggerated fashion to normal TSH levels

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A. Non toxic goiters

• Pathology
• Diffuse non toxic goiter
• Early stage of the disease
• The gland is diffusely enlarge
• Microscopically ? it exhibits hypertrophy and
  hyperplasia of follicular epithelial cells

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Non toxic goiters

• Pathology
• Multinodular non toxic goiter
• Evolves as the disease becomes more chronic
• Many patients develop TOXIC multinodular goiters
• The enlarged gland assumes an increasingly
  nodular configuration
• Microscopically,
• The nodules vary in size and shape.Some are
  distended with colloid and others are collapsed
• Lining epithelial cells are flat to cuboidal and
  are arrayed as papillae that project into
  follicular lumen
• Hemorrhagic, necrotic and cystic areas are common
  and fibrous band traverse the gland.

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A. Non toxic goiters

• Clinical features
• Patients are asymptomatic presenting with a mass
  in the neck
• Large goiters ? compress trachea and esophagus ?
  cause inspiratory stridor or dysphagia
• Hoarseness result from compression pf recurrent
  laryngeal nerve
• Thyroid function test TSH, T4, T3 normal

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A. Non toxic goiters

• Treatment
• Administration of thyroid hormone to reduce TSH
  levels and stimulation to thyroid growth
• In older patients, Radioactive iodine therapy is
  indicated
• Surgery is contraindicated unless the local
  obstructive symptoms become troublesome.

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B. Thyroid cancer

• It is more common in females between the 30 70s
  years of age
• Types
• Papillary
• Follicular
• Medullary
• Anaplastic undifferentatited

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B. Thyroid cancer

• Papillary thyroid carcinoma
• The most common thyroid cancer
• Pathogenesis
• Iodine excess
• Previous radiation to the neck
• Genetic factors such as HLA DR7
• Pathology
• Orphan Annie nuclei
• Eosinophilic pseudoinclusions
• Nuclear grooves

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Orphan Annie nucleus
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B. Thyroid cancer

• Follicular thyroid carcinoma
• 15 25 of all thyroid cancers
• It could be minimally invasive or widely invasive
  ? blood borne metastasis
• Metastasis are directed to the bones of the
  shoulder, pelvis, sternum and skull
• Some patients present with pathological fractures
  due to metastasis
• Treatment Radio labeled Iodine

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B. Thyroid cancer

• Medullary thyroid carcinoma
• Tumor derived from parafollicular or C cells
• Less than 5 of thyroid carcinomas
• Patients having familial form of this carcinoma
  are afflicted with MEN type 2 that includes
  pheochromocytoma of the adrenal medulla and
  parathyroid hyperplasia
• Pathology
• Presence of stromal amyloid which represents the
  deposition of procalcitonin

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B. Thyroid cancer

• Anaplastic Undifferentiated thyroid carcinoma
• Rapidly fatal
• History of long standing goiter
• Invasion of the soft tissues of the neck
• Pathology
• Sarcoma like proliferation of spindles and giant
  cells with polyploid nuclei, necrosis and stromal
  fibrosis

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Hyperthyroidism

• Refers to the clinical consequences of excessive
  circulating thyroid hormone
• Graves Disease
• Toxic multinodular goiter
• Toxic adenoma

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1. Graves Disease

• Autoimmune disorder that is characterized by
  diffuse goiter, hyperthyroidism and exophthalmos
• Most frequent cause of hyperthyroidism in
  patients younger than 40 years of age

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1. Graves Disease

• Pathogenesis
• Immune mechanism
• Patients are hyperthyroid owing to the presence
  of IgG antibodies directed against components of
  the plasma membrane of the thyroid follicular
  epithelium presumably the TSH receptor
• These antibodies function as an agonist they
  stimulate the TSH receptor ? activate adenyl
  cyclase ? increase in thyroid hormone secretion
• Under continuous stimulation, the thyroid becomes
  diffusely hyperplastic and excessively vascular
• Patients with Graves disease and their relatives
  both have a higher incidence of other autoimmune
  disease including pernicious anemia and Hashimoto
  thyroiditis

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1. Graves Disease

• Pathogenesis
• Sex
• More common in females than males
• Emotional influences
• The onset of Graves disease often follows a
  period of emotional stress.
• Opthalmopathy
• Exophthalmos is a common complication of Graves
  disease
• T lymphocytes that are sensitized to antigens
  shared by thyroid follicular cells and orbital
  fibroblasts accumulate around the eye where they
  secrete cytokines that activate fibroblasts.

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1. Graves Disease

• Pathology
• The thyroid is symmetrically enlarged
• Microscopically,
• The thyroid is diffusely hyperplastic and highly
  vascular
• The epithelial cells are tall and columnar and
  are often arranged as papillae that project into
  the lumen of the follicles
• The colloid tends to be depleted and presents a
  scalloped moth-eaten appearance
• Scattered lymphocytes and plasma cells infiltrate
  the interstitial tissue

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Graves Disease

• Clinical features
• gradual onset of nonspecific symptoms such as
  nervousness, emotional lability, tremor, weakness
  and weight loss
• They are intolerant of heat, and tend to sweat
  profusely
• Almost all patients exhibit tachycardia or
  palpitations
• Physical examination reveals
• a symmetrically enlarged thyroid often with an
  audible bruit and palpable thrill
• Protrusion of the eyeball and retraction of the
  eyelids expose the sclera
• The skin is warm and moist
• Some patients exhibit Graves dermopathy which is
  a peculiar pretibial edema caused by the
  accumulation of fluid and glycosaminoglycans

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1. Graves Disease

• Treatment
• antithyroid drugs
• Radioiodine
• adjuvant therapy with corticosteroids
• adrenergic anatagonist

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2. Toxic Multinodular Goiter

• Many patients who are older than 50 years of age
  develop functional autonomy of the nodules and a
  toxic form of the disease
• More frequent in women
• Never develop exophthalmos
• Patients complain of cardiac complications such
  as atrial fibrillation and congestive heart
  failure
• Serum T4 T3 are minimally elevated
• Microscopic examination reveals groups of small
  hyperplasic follicles mixed with other nodules of
  varying size that appear to be inactive.
• Treatment radio labeled iodine

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3. Toxic adenoma

• A solitary hyperfunctioning follicular neoplasm
  in a normal thyroid
• Hyperfunctioning of the adenoma suppresses the
  remainder of the thyroid which then atrophies
• Treatment radiolabeled iodine and surgery for
  large nodules.

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Hypothyroidism

• Refers to the clinical manifestation of the
  thyroid hormone deficiency
• It can be the consequence of 3 general processes
• Defective synthesis of the thyroid hormone
• Inadequate function of the thyroid parenchyma
• Inadequate secretion of TSH by the pituitary or
  TRH by the hypothalamus

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1. Hashimoto Thyroiditis

• An autoimmune disease that is characterized by
  circulating antibodies to thyroid antigens and
  features that are suggestive of cell-mediated
  immunity to thyroid tissue
• Arises most commonly in women during the 4th and
  5th decades of life
• in regions where supplies of Iodine are adequate
  ? Hashimoto thyroiditis is the most common cause
  of goitrous hypothyroidism

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1. Hashimoto Thyroiditis

• Pathogenesis
• Patients exhibit high titers of circulating
  autoantibodies directed against thyroid
  peroxidase, thyroglobulin and the TSH receptor
• The intense filtration of the thyroid parenchyma
  by lymphocytes and plasma cells suggest
  cell-mediated destruction of the gland
• Both patients of Hashimoto and their relatives
  have a higher incidence of other autoimmune
  diseases, such as Insulin dependent diabetes
  mellitus, pernicious anemia, Addison disease, and
  myasthenia gravis
• Hashimoto is associated with an increased
  frequency of the HLA- B8, HLA-Dr3, and HLA-DR5
  haplotypes

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1. Hashimoto Thyroidtis

• Pathology
• The gland in Hashimoto is diffusely enlarged,
  firm and slightly lobular
• Microscopically, the gland displays
• Infiltrate of lymphocytes and plasma cells
• Destruction and atrophy of the follicles
• Oxyphilic metaplasia of the follicular epithelial
  cells

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1. Hashimoto Thyroiditis

• Clinical features
• The patient notes a gradual onset of a goiter
• Majority of these patients are euthyroid, few are
  hypothyroid when they present for medical
  attention
• Most cases progress to a hypothyroid state
• Many patients require no treatment
• Thyroid hormone is administered to alleviate
  hypothyroidism and to decrease the size of the
  gland

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2. Subacute Thyroiditis

• It is also called (DeQuervain, Granulomatous, or
  Giant cell thyroiditis)
• Infrequent self-limited viral infection of the
  thyroid that is characterized by granulomatous
  inflammation
• The disease typically occurs after upper
  respiratory tract infections including those
  caused by Influenza Virus, adenovirus, echovirus,
  and coxsackievirus
• Affect women between 30 50 years of age

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2. Subacute thyroiditis

• Pathology
• The gland is enlarged and the cut surface is firm
  and pale
• Microscopic examination reveals
• An acute inflammatory reaction often with micro
  abscesses
• Appearance of a patchy infiltrate of lymphocytes,
  plasma cells and macrophages throughout the gland
  
• Numerous multinucleated giant cell of the foreign
  body type often containing colloid

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2. Subacute Thyroiditis

• Clinical features
• Pain in the anterior neck which is sometimes
  accompanied by fever
• On physical examination, the thyroid is
  moderately enlarged and tender
• Generally resolves within a few months and
  without clinical sequelae

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3. Riedel thyroiditis

• Rare disease that is characterized by dense
  fibrosis of the thyroid
• The disease involves extrathyroid soft tissues of
  the neck and is often associated with progressive
  fibrosis in other locations including the
  reroperitoneum, mediastinum, and orbit
• A disease of middle age with a female male ratio
  of 31
• Cause is unknown
• Patients notice a gradual onset of painless
  goiter
• Patients may suffer from the consequences of
  compression of the trachea, esophagus and
  recurrent laryngeal nerves
• Treatment is primarily surgical to relieve
  compression of local organs

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