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)
- Papillary (75-85%; more common in young patients 20-40)
- Parafollicular C cells
- Medullary (5-8%; >40)
- Tumours of clear (C) cells
- Often associated with MEN syndrome type 2
- Medullary (5-8%; >40)
- Follicular
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