Thyroid Carcinoma

CAUSES AND RISK FACTORS:
  • Chronic Iodine deficiency ↑ risk for Follicular carcinoma.
Gender:
  • Female > Males.
Age:
  • More common at young adults.
  • MTC usually diagnosed after 60.
Race:
  • White race > Black race.
Genetics:
  • Abnormal RET oncogene may cause MTC.
  • MEN 2A, 2B Syndrome.
  • Family History:
  • Hx of goiters increase risk for Papillary Ca.
  • Gardner’s Syndrome and FAP increase risk for Papillary Ca.
  • Radiation Exposure:
  • Radiation therapy to Head or Neck.
  • Exposure to Radioactive Iodine during childhood, or other radioactive substances (Chernobyl) ↑ risk for particularly Papillary carcinoma.
PRESENTATION:
  • Solitary or Multiple thyroid nodules
  • Neck Nodes
  • Hoarse voice of recent onset
  • Mediastinal adenopathy
  • Bone or lung metastasis
IMPORTANT HISTORY
  • Radiation to neck / chest
  • MEN syndrome
  • Family history
  • Diarrhoea
  • Adrenal tumour
  • Recent change in a pre-existing goitre
  • Size change/nodularity
  • Vocal cord palsy
EVALUATION:
  • Thyroid profile
  • Serum Thyroglobulin
  • Serum Calcitonin
  • Thyroid scan
  • Hot/warm/cold nodule 20% malignant
  • Serum Ca++
DIAGNOSIS:
  • Imaging
  1. U/S
  2. C.T
  3. MRI
  • Scintigraphy (I-123)
  • Staging of follicular and papillary Ca
  • Characterizing funtioning nodules
Laboratory:
  1. TSH
  2. T3, T4
  3. Serum Thyroglobulin
  4. Serum Thyroid Antibodies
  5. FNAC
  • Most patients are Euthyroid.
  • Hyperfunctioning nodule à 1% chance of malignancy.
  • Serum Tg cannot differentiate between benign and Malignant nodules
Tg is used for:
  1. F/U after total thyroidectomy
  2. Serial F/U for non-operative treatment
  • Serum Calcitonin à patients with MTC, or with family hx of MTC (MEN2)
PAPILLARY CARCINOMA:
  • Most common Thyroid carcinoma (80%)
  • Related to radiation exposure in I-sufficient areas.
  • Female:male ratio is 2:1
  • Mean age of presentation is 30 to 40 yrs.
  • Slow growing painless mass. Euthyroid-status.
  • LN metastases is common, may be the presenting symptom (Lateral Aberrant Thyroid).
  • Distant metastases is uncommon at initial presentation.
  • Develop in 20% of cases. (Lungs, liver, bones,brain)
  • FNA biopsy is diagnostic.

FOLLICULAR CARCINOMA:
  • Account for 10% of all thyroid cancers.
  • More common in I-deficient areas.
  • Female:male ratio is 3:1
  • Mean age at presentation is 50 yrs.
  • Solitary thyroid nodule, rapid increase in size and long-standing goiter.
  • Cervical LN metastasis is uncommon at presentation (5%), distant metastasis may be present.
  • Hyperfunctioning < 1%. (S&S of Thyrotoxicosis)
  • FNA biopsy cannot differentiate between benign and malignant follicular tumors.
  • Pre-operative diagnosis of malignancy is difficult unless there is distant metastasis.
  • Large follicular tumor > 4 cm in old individual à CA.
MEDULLARY CARCINOMA:
  • 5% of all thyroid malignancies.
  • Arise from Parafollicular cells, concentrated in superolateral aspect of thyroid lobes.
  • Most cases are sporadic, 25% are inherited (Germline mutation in RET oncogene).
  • Female:Male ratio is 1.5:1
  • Most patients present between 50 and 60 yrs.
  • Neck mass + palpable cervical LN (15-20%).
  • Local pain or aching is common.
MTC secrets a range of compounds:
  1. Calcitonin, CEA, CGRP, PG A2 and F2α, Seritonin.
  2. May develop flushing and diarrhoea, Cushing’s syndome (ectopic ACTH).
  3. Diagnosis
  • Hx and P/E (Family hx of similar tumors).
  1. ↑ Serum Calcitonin, ↑ CEA
  2. FNAC
Screen patient for:
  1. RET point mutation.
  2. Coexisting Pheochromocytoma (24-hour urinary level of VMA, catecholamine, metanephrine).
  3. Hyperparathyroidism (Serum calcium).

ANAPLASTIC CARCINOMA:
  • 1% of all thyroid malignancies.
  • Women > Men.
  • Majority present at 7th - 8th decade of life.
  • Long-standing neck mass, rapidly enlarging in size.
  • May be painful, with dyphonia, dyspnea, dysphagia.
  • LN are usually involved at presentation.
  • ± Distant metastasis.

PROGNOSIS:

Tumor Prognosis
Papillary Ca. 74-93% long-term survival rate
Follicular Ca. 43-94% long-term survival rate
Hurthle Cell Ca. 20% mortality rate at 10 years
Medullary Ca. 80% 10-year survival rate45% with LN involvement
Anaplastic Tumor Median survival of 4 to 5 months at time of diagnosis
Exam Question
  • Thyroid carcinoma associated with hypocalcemia is Medullary carcinoma
  • FNAC cannot distinguish between a Follicular Adenoma and a Follicular Carcinoma
  • In Medullary carcinoma thyroid Patients should be screened for RET point mutation on chromosome 10
  • Medullary carcinoma thyroid Secretes calcitonin
  • Medullary carcinoma thyroid Contains amyloid
  • Papillary carcinoma of thyroid have Excellent prognosis
  • Amyloid deposition is seen in Medullary carcinoma thyroid
  • Total thyroidectomy is done in Medullary carcinoma thyroid
  • Parafollicular cells involved in Medullary carcinoma thyroid
  • Medullary carcinoma thyroid is TSH dependent
  • Radionuclide scan is is initial investigation of choice for a patient presenting with solitary nodule of thyroid
  • Percentage of cold thyroid nodules likely to be malignant are 20%
  • Psammoma bodies are seen in Seminaoma
  • Medullary thyroid carcinoma is associated with MEN II
  • Multiple,round figures in histopathological picture of a patient suffering from carcinoma is due to a mineral deposition can be diagnosed to have Adenocarcinoma of Lung, Meningioma or papillary thyroid carcinoma.
  • Medullary thyroid carcinoma is classically associated with calcitonin induced amyloid deposition
Don't Forget to Solve all the previous Year Question asked on Thyroid Carcinoma