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Flashcards in thyroid nodules Deck (20):

How are thyroid nodules usually discovered

Most are noted by patient, then noted by third party or detected by other tests. Ultrasound > CT > PET


How common are thyroid nodules and how often are they cancerous

Nearly 60% of people will get a thyroid nodule but only 10-15% are cancer.


List the most common benign and malignant thyroid masses

Benign: adenoma. Malignant: papillary (85-90%), follicular (5%), anaplastic (<2%), medullary (5%), lymphoma, sarcoma and metastatic are rare


Types of follicular/hurthle cell carcinomas

1. minimally invasive- vascular or capsular invasion. 2. Widely invasive - more extensive


Papillary carcinoma characteristics

well differentiated, lymphatic spread, excellent prognosis


Papillary carcinoma histology

Papillae with vascular core, optically clear nuclei, neuclear pseudoinclusions, nuclear grooves, rare or absent mitoses, psammoma bodies


Anaplastic carcinoma characteristics

older age group, poor survival, rapidly growing mass


Patterns of anaplastic carcinoma

spindle cell, giant cells, squamoid cells


Medullary carcinoma histology

Solid proliferation of cells with granular cytoplasm (C cells), Highly vascular stroma, Hyalinized collagen and/or amyloid, May have Psammoma bodies


Immunostains for medullary carcinoma

Thyroglobulin negative, calcitonin positive, chromogranin positive


Thyroid lymphomas

large fleshy masses and background of autoimmune thyroiditis


List cancers which may metastasize to thyroid

melanoma, lung, head and neck, renal, breast, colon


Workup for thyroid nodules

1. TSH. 2. If TSH is low, nuclear imaging. If TSH is high/normal ultrasound. 3. If ultrasound shows nodule, fine needle aspiration. If no nodule on US, don’t do FNA. 4. If FNA is benign, follow. If FNA is malignant, surgery. If FNA is inadequate, re-biopsy. If FNA is suspicious, scan.


Papillary carcinoma of thyroid histology

Highly cellular, +/- colloid, nuclear enlargement and elongation, nuclear grooves and pseudoinclusions, multiple small to large nucleoli, psammoma bodies, papillary cellular aggregates


define proto oncogene

Normal gene which codes for a protein that promotes normal cell division


Define oncogene

Mutated gene which codes for a protein that causes unregulated cell division. Oncogene activation causes tumors


Define tumor suppressor gene

Normal gene which codes for a protein that restrains cell division or that promotes cell differentiation, DNA repair or apoptosis. Tumor suppressor gene loss results in tumors


Molecular mechanisms of papillary carcinoma

RE/PTC rearrangement (20%), Ras point mutation (20%), and/or BRAF point mutation (40%) leads to cell growth and division


Molecuar mechanisms of follicular thyroid carcinoma

Pax8-PPARgamma gene rearangement/fusion leads to abnormal expression in thyroid cells and follicular thyroid carcinoma in 50%.


Describe the progression of thyroid tumor development.

thyroid follicular cell > follicular adenoma (Ras methylation) > follicular carcinoma (Pax8-PPARgamma fusion) > anaplastic carcinoma (p53 and Beta catenin mutations). Also thyroid follicular cell > papillary thyroid carcinoma (RET/PTC, Trk, Met, Ras, BRAF mutations). Also thyroid follicular cell > hyperfunctioning adenoma (TSH-R, g protein mutations)