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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