Thyroid Tumors

Thyroid Tumors

1. Benign

   • Types
     • Follicular Adenoma
       • "Cold"
         • Almost all are cold
           • May still produce worrisome symptoms
             • Compression of trachea
             • Dysphagia
       • "Hot"
         • Functioning
           • Clinical Findings
             • Increased radioactive iodine uptake
             • May have signs of hyperthyroidism
       • Subtypes
         • Macro (colloid)
         • Normo
         • Micro
         • Trabecular
       • General
         • Most common benign thyroid tumor
         • Encapsulated tumor with follicular differentiation
         • Very low malignant potential
         • Almost always solitary
       • Treatment
         • Partial or complete thyroidectomy
     • Solitary Nodule
     • Granular Cell Tumor

2. Malignant

   • Types
     • Papillary Carcinoma
       • General
         • Most common thyroid malignancy
         • F>M, 3:1
         • a/w childhood radiation exposure
         • Excellent prognosis
       • Gross and Microscopic Findings
         • Multifocal
         • Empty appearing nuclei
           • Orphan Annie eyes
         • Papillary projections within glandular space
         • Psamomma bodies
           • Collection of calcified cancer cells; stain deep purple
         • Lymphatic invasion
           • Mets to cervical LNs and lung
       • Diagnosis and Treatment
         • Dx: FNA
         • Partial or complete thyroidectomy
           • Followed by radiotherapy with radioactive Iodine
         • Suppression therapy
           • levothyroxine to increase negative feedback on TSH secretion
             • Shrinks the tumor
     • Follicular Carcinoma
       • General
         • F>M
         • Good prognosis
         • a/w radiation exposure (less so than papillary) and iodine deficiency
       • Gross and Microscopic Findings
         • Usually a single cold, encapsulated nodule
         • Haematogenous spread
           • Rather than lymphatic spread as seen in papillary carcinoma
           • Mets to lung and bone first
         • Well-differentiated, uniform follicles
         • No psamomma bodies
         • Widely invasive or minimally invasive classification
           • Minimally invasive: capsule invasion only (may have some vascular invasion of a few small vessels) Widely invasive: extends through capsule and into thyroid parenchyma and vasculature
       • Hurthle cell carcinoma often considered a variant
       • Diagnosis and Treatment
         • FNA is NOT diagnostic
           • Microscopically the same as follicular adenoma
             • Need evidence of invasion
         • Definitive dx requires lobectomy
         • Treated similarly to papillary carcinoma
     • Medullary Carcinoma
       • Findings
         • Increased serum calcitonin
           • Causes diarrhoea
           • Tumor marker
         • May have ectopic hormone production, paraneoplastic syndromes
           • Ex. ACTH causing Cushing syndrome
         • Calcitonin amyloid material in stroma
         • Mets
           • Early regional LN mets common
           • Distant mets to liver, lung, bone and brain
       • Diagnosis and Treatment
         • Dx: FNA, increased calcitonin
         • Total thyroidectomy and genetic screening of RET gene if familial
       • General
         • Neuroendocrine tumor of parafollicular C cells
           • C-cell hyperplasia is a precursor lesion
         • Causes
           • Sporadic (80%)
             • Poorer prognosis than familial type
             • Unilateral
           • Familial (20%)
             • a/w MEN 2A and 2B
               • Recall:  MEN 2A- medullary carcinoma, hyperparathyroidism, pheochromocytoma MEN 2B- medullary carcinoma, mucosal neuromas, pheochromocytoma
             • Younger patients
             • Bilateral and multicentric
     • Anaplastic
       • General
         • Elderly women
         • a/w multinodular goiter and positive follicular cancer history
         • Rapidly aggressive
           • VERY poor prognosis
           • Early dissemination
           • Invasion of local structures (trachea, oesophagus) common
           • 50% have lung mets at presentation
       • Gross and Microscopic Findings
         • Regions of spontaneous haemorrhage and necrosis
         • Infiltration of adjacent structures
       • Diagnosis and Treatment
         • Dx: FNA or surgery if inconclusive
         • Palliative treatment
           • Partial surgical resection
             • Tumor often compresses the trachea
             • Extensive resection of tumor and surrounding structures generally NOT indicated
               • High post-op morbidity
                 • Ex. vocal cord paralysis
               • No proven survival benefit
           • Chemo or radiation
     • Primary B Cell Lymphoma
       • Most commonly a/w Hashimoto's thyroiditis

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