Thyroid tumours
How the thyroid’s two cell lines give rise to its tumours: common benign nodules and follicular adenomas, papillary and follicular carcinoma, medullary carcinoma from C cells, and rare, rapidly invasive anaplastic carcinoma.
By the end, you can
- Relate follicular cells and C cells to the tumours that arise from each, and explain why most thyroid nodules are benign.
- Describe the gross and microscopic features of papillary carcinoma and explain why it spreads to neck nodes.
- Explain why follicular carcinoma is diagnosed by capsular or vascular invasion and spreads through the blood.
- Relate medullary carcinoma to calcitonin, amyloid and inherited RET mutations, and anaplastic carcinoma to dedifferentiation and local invasion.
- Explain what grading and staging measure in thyroid cancer and why age enters its staging.
- Recognise the classic microscopic features, Bethesda categories, ultrasound features and markers of thyroid tumours, and explain how thyroidectomy, radioactive iodine, TSH suppression and kinase inhibitors act on what each tumour keeps from its cell of origin.
What it is
Thyroid tumours arise mostly from follicular cells (follicular adenoma; papillary, follicular and oncocytic carcinoma; and, by dedifferentiation, poorly differentiated and anaplastic carcinoma) and less often from C cells (medullary carcinoma). Most thyroid nodules are benign; most thyroid cancers are well differentiated and grow slowly, while anaplastic carcinoma is among the most aggressive human cancers.
5 types to tell apart
- Follicular adenoma
- A benign, encapsulated tumour of follicular cells with no capsular or vascular invasion.
- Papillary carcinoma
- The commonest thyroid cancer, defined by its nuclei; spreads through lymphatics to neck nodes.
- Follicular carcinoma
- Defined by invasion of its capsule or vessels; spreads through the blood to bone and lung.
- Medullary carcinoma
- From C cells; secretes calcitonin; about a quarter are inherited through RET mutations (MEN2).
- Anaplastic carcinoma
- Undifferentiated, often arising from a differentiated carcinoma; invades the neck within weeks.
US spelling: tumours → tumors, oesophagus → esophagus.
Normal function
Follicles, C cells and lymph drainage
The has two lobes joined by an across the front of the . Its units are follicles: spheres of follicular epithelium around a store of colloid. Follicular cells trap iodide, make thyroglobulin and release T4 and T3 under the control of TSH, which is also a growth signal for them.
Scattered between the follicles are C cells (parafollicular cells), which come from the neural crest and make calcitonin. The two cell lines give rise to different tumours: follicular cells to almost all thyroid tumours, C cells to medullary carcinoma.
Lymph drains first to central nodes beside the trachea and then to the deep cervical nodes along the internal jugular vein. Behind each lobe lie the and the recurrent laryngeal nerve, which moves the vocal cord; the lies behind the trachea.
Underlying change · Step 1 of 5
Nodules and follicular adenoma
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 5
Papillary carcinoma: nuclei and lymph nodes
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 5
Follicular carcinoma: invasion and blood-borne spread
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 4 of 5
Medullary and anaplastic carcinoma
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
Effects, grading and staging
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .