Thyroid neoplasia

Background

  • Usually present with a solitary nodule.
    • Most are benign; some ‘toxic’ adenomas also secrete excess thyroid hormone causing a mild hyperthyroidism.
  • More common in females
  • Can be classified according to the cell type of origin
    • Follicular
      • Papillary (75-85%; more common in young patients 20-40)
        • Seldom encapsulated so can spread, but usually only to lymph nodes (haematogenous and distant metastasis is rare)
      • Follicular (10-20%; more common in older patients 40-60)
        • Usually encapsulated (adenoma- single nodule) so spread is rare
        • If it does spread (carcinoma), it does so commonly to bones (presentation may be with a pathological fracture)
      • Anaplastic (<5%; usually >60)
        • Characteristically poorly differentiated, quite rapidly enlarging and locally invasive (may present with local symptoms e.g. hoarseness, stridor, pain etc)
    • Parafollicular C cells
      • Medullary (5-8%; >40)
        • Tumours of clear (C) cells
        • Often associated with MEN syndrome type 2

Toxic Adenoma

  • <5% of cases of hyperthyroidism; most cases female and >40.
  • Follicular adenoma (usually >3cm) which secretes thyroid hormone; inhibiting TSH secretion and causing atrophy of the rest of the thyroid gland
    • Thyrotoxicosis (and thus symptoms) is usually mild (often only elevated T3
  • Diagnosis with scintigraphy
  • Management is radioactive iodine (highly effective).  Often patients do not require supplementary thyroxine post-treatment as the unaffected normal thyroid gland can respond to normalised TSH levels.

Differentiated Thyroid Cancer

Risk Factors

  • Exposure to ionising radiation (esp papillary carcinoma), particularly at a young age
  • Family history of thyroid disease and thyroid cancer
  • Genetic predisposition: MEN2 (RET gene mutation); particularly medullary carcinoma

Presentation

  • Thyroid nodule, often hard and craggy feeling, and can be fixed; usually non-tender but insidious/persistent pain is worrying
  • Lymphadenopathy can also be present (papillary ca)
  • Other features of local compression may be present e.g. dysphagia, stridor, hoarseness
  • Important to ask about general features of cancer e.g. weight loss, sweats etc, although this is rare in thyroid cancers

Investigations

  • TFTs are often normal
  • Scintigraphy usually shows a ‘cold’ nodule (particularly in larger tumours) or can be normal
  • USS and FNA is is the diagnostic investigation

Management

  • Almost always surgery (total thyroidectomy) +/- radioactive ablation
    • + supplementary thyroxine for life

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