fna of the thyroid
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FNA of the Thyroid
Lisa Kendrick BSc., RT Cytology, CT (ASCP)
School of Diagnostic Cytology
Health Sciences Centre
Objectives
Describe the anatomy of the thyroid. Describe the histologic features of the thyroid List and describe the normal cytologic features of the thyroid. State the requirement of adequacy for a FNA of the thyroid. List and describe the common benign conditions of the thyroid. List and describe the common malignancies of the thyroid. List and describe the common metastatic malignancies of the
thyroid. Discuss the various methods of treatment of malignancies of the
thyroid.
Anatomy
Located below the larynx Consists of two lobes
that lie on either side of the trachea
Lobes are connected by an ithmus
Is an endocrine gland
Concepts of Human Anatomy and Physiology, Van de Graff and Fox, page 504, Figure 19.13
Histology
Consists of spherical sacs – thyroid follicles
Lined by simple cuboidal epithelium
Contains colloid
Wheater’s Functional Histology 3rd Edition, Burkitt, Young and Heath, page 310, Figure 17.7
Thyroid - Histology
Cells of the Thyroid
Follicular Cells
Nucleus– Central– Round/oval– Finely granular chromatin– 1 – 2 nucleoli
Cytoplasm– Pale– Indistinct
Arrangement– Honeycomb pattern
Hurthle Cells
AKA Askanazy cells or Oncocytes
Large, polygonal cells Nucleus
– Round/oval– Eccentric– Finely granular chromatin
Cytoplasm– Abundant– Granular – Eosinophilic
Colloid
Found in the background May stain blue, pink or metachromatic Two states:
– Watery Thick
Satisfactory Specimen
5 or more groups of 10 cells each on a minimum of 2 slides
Benign Conditions of the Thyroid
Colloid Nodule
Most common form of goiter in adolescents and young women
Follicular cells cease to proliferate and colloid accumulates within the follicles
Colloid Nodule
Cytology– Macrofollicular pattern– Variable cellularity– Hurthle cell change may
be seen– Scant follicular cells
(normal in appearance)– Macrophages– Abundant colloid
Cystic Degeneration
FNA can cure 20 – 60% of cystic lesions by evacuation Cytology
– Few follicular cells– Abundant macrophages
Hashimoto’s Thyroiditis
AKA chronic thyroiditis An autoimmune disorder Affects women more than men Associated with hyperthyroidism
Hashimoto’s Thyroiditis
Cytology– Cellular aspirate presenting in small groups, fragments– Groups of Hurthle cells– Follicular cells with Hurthle cell
change– Inflammatory cells
(lymphocytes and macrophages)
– Tingible body macrophages– Little colloid– Possible lymphoma
association
Malignancies of the Thyroid
Follicular Carcinoma
Peak onset ages 40 through 60 Females more common than males by 3 to 1 ratio Prognosis directly related to tumor size [less than 1.0 cm (3/8 inch) good
prognosis] Rarely associated with radiation exposure Spread to lymph nodes is uncommon (~10%) Invasion into vascular structures (veins and arteries) within the thyroid
gland is common Distant spread (to lungs or bones) is uncommon, but more common than
with papillary cancer Overall cure rate high (near 95% for small lesions in young patients),
decreases with advanced age
www.endocrineweb.com/capap.html
Follicular Carcinoma
Distinction between neoplasm and carcinoma depends on the histology specimen
Identification of invasion of either the capsule or blood vessels confirms the diagnosis of carcinoma
It is very difficult to differentiate between neoplasm and carcinoma based on morphology alone
Follicular Neoplasms
• The cellularity varies• No colloid• Cells are arranged in small, loosely cohesive groups• Micro follicular pattern is observed• Syncytial patterns predominate• There may be overlap of some features with a
colloid nodule
Follicular Neoplasm
Nucleus – Round– Smooth membrane– Fine/coarse even
chromatin– Macronucleoli
Cytoplasm – Pale – Poorly defined
Papillary Carcinoma
Peak onset ages 30 through 50 Females more common than males by 3 to 1 ratio Prognosis directly related to tumor size [less than 1.5 cm (1/2
inch) good prognosis] Accounts for 85% of thyroid cancers due to radiation exposure Spread to lymph nodes of the neck present in more than 50% of
cases Distant spread (to lungs or bones) is very uncommon Overall cure rate very high (near 100% for small lesions in young
patients)
www.endocrineweb.com/capap.html
Papillary Carcinoma
Highly variable cellularity
(very cellular to scant or cystic) Little to no colloid Papillary arrangements or monolayered
fragments Syncytia may be present Enlarged polygonal cells
Papillary Carcinoma
Nucleus– Central– Overlapping– Round/oval/pleomorphic/
angulated– Finely granular (powdery)
chromatin– Micro or macro nucleoli– Folds and creases (grooves)– Cytoplasmic nuclear inclusions
Abundant cytoplasm Psammoma bodies may be
present Multinucleated macrophages
Hurthle Cell Neoplasm
Cellularity varies Little to no colloid Cells are dispersed or
arranged in loose monolayers May be follicular growth
pattern Monomorphic population of
Hurthle cells– May have red macronucleoli– May demonstrate
binucleation– May demonstrate nuclear
grooving
Hurthle Cell Neoplasm
There is no clear separation between adenomas and carcinoma
However if the following features are present a carcinoma may be suspected:– Hypercellularity– Syncytia– Increased N:C– Nuclear pleomorphism– Multinucleoli
Medullary Carcinoma
Occurs in 4 clinical settings and can be associated with other endocrine tumors
Females more common than males (except for inherited cancers) Regional metastases (spread to neck lymph nodes) occurs early in the
disease Spread to distant organs (metastasis) occurs late and can be to the liver,
bone, brain, and adrenal medulla Not associated with radiation exposure Usually originates in the upper central lobe of the thyroid Poor prognostic factors include age >50, male, distant spread
(metastases), and when seen in patients with other endocrine tumors due to MEN II-B syndrome.
Residual disease (following surgery) or recurrence can be detected by measuring calcitonin (a hormone that should be measured every 4 months for the first few years and then every 6 months for ever).
www.endocrineweb.com/capap.html
4 Variants
Sporadic MEN II-A (Sipple Syndrome) MEN II-B Inherited Medullary Carcinoma
Medullary Carcinoma
Not a common malignancy Can be multifocal (in which the clinician may
remove the entire thyroid) Lymph node involvement is common
Medullary Carcinoma
• Cellularity varies• Cell morphology varies
• Plasmacytoid• Round• Polygonal• Spindle
• Arranged in loose groups• Single cells are common• Amyloid may be present
in the background
Medullary Carcinoma
Nuclei– Oval/pleomorphic– Coarse salt and pepper chromatin pattern– Central or eccentrically located– Indistinct nucleoli– Binucleation may be seen
• Intranuclear inclusions may be seen
Cytoplasm is finely granular
Anaplastic Carcinoma
Very rare Diagnosis is often suggested by clinical
findings
Peak onset age 65 and older Very rare in young patients Females more common than in males Typically presents as rapidly growing neck mass Can occur many years after radiation exposure Spread to lymph nodes of the neck present in more than 90% of cases Distant spread (to lungs or bones) is very common even when first
diagnosed Overall cure rate very low Typically requires a very aggressive treatment plan with surgery, radiation
and sometimes even chemotherapy. Often requires the patient to get a tracheostomy to maintain their airway.
www.endocrineweb.com/capap.html
Anaplastic Carcinoma
Giant or mixed forms Variable cellularity Inflammatory cells and necrotic debris are
found in the background Variable cell morphology
– Squamoid– Giant cell– Spindle cell
Anaplastic Carcinoma
Nucleus– Pleomorphic in shape– Irregular membrane– Coarse, irregularly
distributed chromatin– Prominent nucleoli– Atypical mitosis– Multinucleation
Cytoplasm– Densely granular
Metastatic Malignancies
Metastatic Malignancies
Thyroid is a common site for metastases Common metastatic tumors include:
– Adenocarcinoma of the breast– Renal cell carcinoma– Squamous cell carcinoma from elsewhere– Melanoma– Lymphoma
Metastatic Melanoma
Cells are very pleomorphic
Pigment is often not present
Clinical history is very important
Immunohistochemistry aids in the diagnosis (S100, HMB45)
Lymphoma
Non-Hodgkin’s Hodgkin’s– monotonous population - Lymphoid cells and of
lymphoid cells Reed-Sternberg cells
Treatment Methods
Surgery
Two types– 1. Lobectomy
The entire thyroid is removed.
– 2. Hemithyroidectomy (lobectomy): The surgeon removes the entire lobe on the side of the
thyroid where the growth or cancer is found. If a biopsy of the growth confirms cancer, the surgeon may also remove the other lobe.
Radiation Therapy
Three types of radiation therapy:– 1. External beam radiation therapy - In external beam radiation therapy, radiation is directed at the cancer and surrounding tissue from a machine
outside the body. It is used to treat most types of cancer. – 2. Brachytherapy - treats the cancer with a high total dose of radiation in a concentrated area in a short period of time. Sealed radioactive sources are placed in the body, in or near the cancer. A sealed radioactive source is often called an implant. – 3. Systemic radiation therapy - the radiation source is given as a liquid (either as a drink or in capsules that are swallowed) or by injecting it into a
vein (an intravenous injection). The radiation source travels throughout the body.
Radioactive Iodine Therapy (RAI)
• Radioactive iodine (also called iodine-131 or I-131) is commonly used to treat thyroid cancer. It is given either as a drink or as a capsule. Thyroid cells and cancer cells absorb the radioactive iodine. It destroys any cancer cells and normal thyroid cells that may still be in the body after surgery.
• After radioactive iodine therapy, thyroid hormone replacement therapy is required to replace the hormone that was made by the thyroid cells.
Thyroid Hormone Treatment
• Thyroid hormone therapy is sometimes used to treat papillary or follicular thyroid cancer. It is given as pills. The hormone thyroxine (T4) slows the growth of thyroid cancer cells that may be left in the body after surgery.
Classification and Staging
TMN Classification (T – tumor, N = node, M = metastases
T1 < 1cm, limited to thyroid
T2 > 1cm, < 4cm, limited to thyroid
T3 > 4cm, limited to thyroid
T4 extension beyond capsule
N1a - Ipsilateral cervical
N1b – Bilateral/midline/contralateral/cervical/mediastinal
M0 – no metastases
M1 - metastases
Stage Grouping – Under 45 years
STI – T any, N any, M0
STII – T any, N any, M1
Stage Grouping – 45 years and older
Stage IA – T0, N any, M0 Stage IB – T1, N any, M0 Stage II – T2, N any, M0 Stage III - T3, N any, M0 Stage IV – T any, N any, M1
Questions?
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