AKT · Endocrine/Thyroid

Thyroid cancer

Malignancy of thyroid follicular/parafollicular cells (papillary/follicular/medullary/anaplastic)

Overview

Thyroid malignancy — papillary (commonest, lymphatic spread, excellent prognosis), follicular (haematogenous, needs histology not cytology), medullary (parafollicular C cells, secretes calcitonin, MEN2-associated), and anaplastic (aggressive, elderly, poor prognosis). Usually a euthyroid solitary nodule; treated with surgery ± radioiodine, then TSH suppression.

Recognise

Painless thyroid nodule (usually euthyroid TFTs), ± cervical lymphadenopathy, hoarseness if locally invasive
Papillary: young, lymph-node spread, psammoma bodies, best prognosis; Follicular: vascular/capsular invasion (needs excision histology)
Medullary: calcitonin-secreting (flushing/diarrhoea), part of MEN2 (RET) — screen family; Anaplastic: rapidly enlarging hard mass in the elderly, airway compromise

Red flags

Rapidly enlarging hard mass + stridor/hoarseness in the elderly → anaplastic — urgent airway/oncology
Medullary cancer → test RET and screen for MEN2 (phaeochromocytoma BEFORE any surgery)

Differentials & how to tell them apart

Benign nodule/multinodular goitrelow-risk ultrasound/cytology, functioning nodule

Lymphoma (thyroid)rapidly growing mass on a background of Hashimoto's

Parathyroid/branchial lesionimaging/biochemistry

Investigations

Ultrasound + FNA cytology (papillary diagnosable on cytology; follicular needs excision). Calcitonin (medullary), RET genetics, CEA. TFTs usually normal. Thyroglobulin as a post-treatment marker.

Management

Surgery (thyroidectomy) ± radioiodine, then TSH-suppressive levothyroxine

1Ultrasound + FNA. Surgery (lobectomy/total thyroidectomy) is the primary treatment for differentiated cancers.Gate: MEDULLARY cancer mandates RET testing + screening for MEN2 — exclude/treat a PHAEOCHROMOCYTOMA before any thyroid surgery (operating with an untreated phaeo can be fatal)
2Radioiodine ablation for differentiated (papillary/follicular) cancer; TSH-suppressive levothyroxine; thyroglobulin/calcitonin surveillance; anaplastic → palliative/airway management.

Total/hemithyroidectomy — primary treatment

Radioiodine ablation — papillary/follicular (iodine-avid) — remnant ablation/metastases

Levothyroxine (TSH-suppressive dose) — reduces recurrence in differentiated cancer

Key points

Papillary = commonest, nodes, great prognosis. Medullary = calcitonin + MEN2 → always exclude phaeo first. Anaplastic = aggressive elderly airway emergency. TFTs are usually normal — it's a structural diagnosis.

Monitor & prognosis

Thyroglobulin (differentiated) / calcitonin (medullary); imaging.

Excellent (papillary/follicular); dire (anaplastic).

Source: British Thyroid Association; NICE NG12