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Thyroid carcinoma 

Etiology

  • Radiation – papillary carcinoma (ca)
  • Pre-existing multinodular goitre – follicular ca
  • Familial – medullary ca
  • Hashimoto’s is a predisposing factor for NHL/papillary ca
  • Genetic – Cowden syndrome
    • differentiated thyroid ca, breast ca, multiple harmatomas

Classification –Dunhill Classification

Differentiated – most common

  • Papillary ca
  • Follicular ca
  • Hurthle ca

Undifferentiated

  • Anaplastic ca

Medullary carcinoma

Malignant lymphoma

Secondaries – from colon, kidney, melanoma, breast

Papillary Carcinoma

Etiology

  • Most common in females and younger age group
  • Radiation – external or internal radio-iodine therapy
  • TSH levels are high in these patients – hormone dependent tumour

Pathoanatomy

  • Gross – can be soft, firm, hard, cystic, solitary or multiple. Contains brownish-black fluid
  • Microscopic – cystic spaces, papillary projections with Psammoma bodies , malignant cells with ‘Orphan Annie eye’

Clinical features

  • Soft/hard/firm, solid/cystic, solitary/multinodular thyroid swelling
  • Compression features are uncommon
  • Neck lymph nodes are palpable – secondaries

Investigations

  • FNAC – of nodule and lymph node
  • Radioisotope scan – cold nodule
  • High TSH level in blood
  • X-ray – calcification
  • US/CT neck – better to see non-palpable node in neck

Treatment

  • Total/near total thyroidectomy with central node compartment dissection
    • Level VI (central compartment) – paratracheal and pretracheal nodes
  • Suppressive dose of L-thyroxine
  • Radioactive 1131 therapy
  • Prognosis – good
    • AMES scoring assessing prognosis

Follicular Carcinoma

Etiology

  • Can occur de novo or in pre-existing multinodular goitre
  • More common in females

Pathophysiology

  • Thyroglobulin is produced by the follicular cells – it produces T3 and T4

Spread

  • Mainly through blood into the bones, lungs, liver
  • Bone secondaries are most common in the skull, long bones, ribs
  • Only 10% spread to the neck lymph nodes

Types

  • Noninvasive – blood spread uncommon
  • Invasive – blood spread common
    • Capsular invasion and angio-invasion

Clinical features

  • Neck swelling – firm or hard nodular
  • Tracheal compression/infiltration, stridor
  • Dyspnea, haemoptysis, chest pain – lung secondaries
  • Recurrent laryngeal nerve involvement – hoarseness
  • Berry’s sign – absence of carotid pulse in presence of neck swelling
    • Signifies advanced malignancy – infiltration into carotid sheath

Investigations

  • FNAC is often inconclusive – unable to detect capsular and angio-invasion
  • US abdomen, CXR, XR of bones
  • Trucut biopsy – gives tissue biopsy, but danger of haemorrhage and injury to vital structures
    • E.g. trachea, recurrent laryngeal nerve, vessels

Treatment

  • Total thyroidectomy with central node compartment dissection (level VI)
  • Functional neck node dissection – with preservation of sternocleidomastoid, spinal accessory nerve, internal jugular vein
  • Lifelong maintenance dose of L-thyroxine

Follow up

  • I131 scan at every 6 months – look for secondaries
  • Thyroglobulin estimation – >50μg signifies recurrent/metastatic disease
    • Normal value – 0.5-50μg

Hurthle Cell Carcinoma

  • Variant of follicular carcinoma which contains abundant oxyphill cells
  • Spreads more commonly to regional lymph nodes than follicular carcinoma

Anaplastic carcinoma

  • Aggressive tumour of short duration, most common in elderly females
  • Presents with swelling in thyroid region, rapidly progresses causing
    • Stridor and hoarseness due to tracheal obstruction
    • Dysphagia
    • Fixity to skin
    • Berry’s sign
  • Swelling is hard, involves isthmus and lateral lobes
  • FNAC – diagnostic
  • Tracheostomy and isthmectomy – relieve respiratory obstruction temporarily
  • Treatment
    • External radiotherapy
    • Chemo – adriamycin
  • Poor prognosis – few weeks to a month

Medullary Carcinoma

  • Arises from parafollicular C cells – derived from the neural crest
  • Contains amyloid stroma – where malignant cells are dispersed
    • Immunohistochemistry – shows calcitonin in amyloid
    • Patients have high blood levels of calcitonin – tumour marker
  • Tumour secretes serotonin, prostaglandin, ACTH, vasoactive intestinal polypeptide
  • Spreads mainly to lymph nodes
  • Sipple’s disease – medullary carcinoma associated with  MEN IIB (most aggressive)
  • Not TSH-dependent – so doesn’t take up radioactive iodine

Clinical features

  • Thyroid swelling and enlarged lymph nodes
  • Diarrhoea, flushing
  • Hypertension, phaeochromocytoma, mucosal neuromas – when associated with MEN II
  • Sporadic and familial types – most common in adulthood

Investigations

  • FNAC – amyloid deposits with dispersed malignant cells and C cell hyperplasia
  • Tumour marker – calcitonin
  • US abdomen and neck

Treatment

  • Total thyroidectomy with central node dissection (VI)
  • No role of suppressive hormone therapy or radioactive iodine
  • External radiotherapy – for residual tumour
  • Somatostatin/octreoide – for diarrhoea
  • Chemotherapy – adriamycin (limited results)

Malignant lymphoma

  • Type of non-Hodgkin lymphoma
  • Frequently associated with Hashimoto’s thyroiditis
  • Diagnosis – FNAC or Tru-cut biopsy
  • Treatment – chemotherapy and radiotherapy
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