bethesda thyroid
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Dr. Pankaj Gupta
October 2007 meeting was organized at National Cancer Institute (NCI), Bethesda, to address the terminology and other issues in thyroid FNA
Idea behind uniform reporting system
• Facilitate effective communication among cytopathologist, radiologist, endocrinologist and surgeon
• Facilitate Histocytological correlation for thyroid disease
• Facilitate research into epidemiology, molecular biology, pathology and diagnosis of thyroid diseases
• Allow easy and reliable sharing of data from different laboratories for national and international collaboration studies
Format of report• Each report begin with six general categories
• Some categories have two alternative names as the consensus was not reached at NCI conference on single name
• Each categories has implied cancer risk ( ranging from 0 to 3% for benign categories to virtually 100% for malignant)
• Additional descriptive comments beyond such subcategorization are optinal and left to discretion of pathologist
Recommended diagnostic categories
1. Non Diagnostic or Unsatisfactory (ND/UNS)
- Cystic fluid only
- Virtually acellular specimen
- Other (obscuring blood, clotting artifacts)
Recommended diagnostic categories
2. Benign
- Consistent with benign follicular nodule
- Consistent with lymphocytic ( Hashimoto’s thyroiditis) in proper clinical context
- Consistent with granulomatous (sub acute) thyroiditis
- Others
Recommended diagnostic categories
3. Atypia of Undetermined significance or Follicular lesion of undermined significance (AUS/FLUS)
Recommended diagnostic categories
4. Follicular neoplasm or Suspicious for Follicular neoplasm (Specify if Hurthle cell or Oncocytic type)
Recommended diagnostic categories
5. Suspicious for malignancy
- Suspicious for Papillary carcinoma
- Suspicious for Medullary carcinoma
- Suspicious for Metastatic carcinoma
- Suspicious for Lymphoma
- Others
Recommended diagnostic categories
6. Malignant- Papillary thyroid carcinoma- Poorly differentiated carcinoma- Medullary thyroid carcinoma- Undifferentiated ( Anaplastic ) carcinoma- Squamous cell carcinoma- Carcinoma with mixed features- Metastatic carcinoma- Non Hodgkin lymphoma- Others
CATEGORY I (Non Diagnostic or Unsatisfactory)
Causes of Unsatisfactory smears
- Obscuring blood
- Overly thick smears
- Air drying of alcohol fixed smears
- Inadequate number of follicular cells
Criteria for adequacy
• At least six groups of benign follicular cells is required with each group composed of at least 10 cells.
• Any specimen that contain abundant colloid is considered adequate
• When a specific diagnosis (e.g. Lymphocytic thyroiditis) can be given or when there is any atypia specimen is by definition adequate
• Specimen containing cyst macrophages only are kept under ND/UNS
• Unless specified in report specimen is considered adequate
Category II ( Benign)• An adequate cellular specimen composed of varying proportion of
colloid and benign follicular cells arranged in macro follicles or macrofollicular fragments are considered as benign follicular nodule
• If nodule shows significant growth or suspicious radiological features then, a repeat FNA is considered
• Other benign categories include Hashimoto thyroiditis, Granulomatous thyroiditis
• Infections, amyloid, black thyroid, reactive changes can be mentioned as descriptive diagnosis
Category III ( AUS/ FLUS)
Most common scenarios for this categorization are
• Prominent population of micro follicles in an aspirate that does not otherwise fulfill the criteria for follicular neoplasm
• Predominance of Hurthle cell in a sparsely cellular smear with scant colloid
• Interpretation of follicular cell atypia is hindered by air drying or clotting artifacts
• A moderately or markedly cellular smear consisting of exclusive population of Hurthle cells yet clinical setting suggest a benign Hurthle cell nodule ( Lymphocytic thyroiditis, Multi nodular goiter)
• There are focal features suggestive of Papillary carcinoma including nuclear grooves, enlarged nuclei with pale chromatin in an other wise predominantly benign appearing sample. ( these can be cyst lining cells)
• A minor population of follicular cells may show nuclear enlargement often accompanied by prominent nucleoli (radioactive iodine, carbamizole, cystic degeneration or hemorrhage)
• There is atypical lymphoid infiltrate but degree of atypia is not sufficient to categorize it as Suspicious for malignancy
• It is important that only nodules with atypical undetermined significance should be placed in this category
• Recognizable benign changes like Hurthle cell change, Black thyroid, Radiation changes should not be classified as AUS
• A moderate or markedly cellular specimen without any significant nuclear or architectural atypia does not qualify for AUS
Category IV (FN/SFN) • Purpose of this category is to identify a nodule that might be a
follicular carcinoma and triage it for surgical lobectomy
• Term suspicious for Follicular neoplasm is preferred over Follicular neoplasm because a significant proportion of cases prove out to be hyperplastic proliferation of follicular cells, most commonly those of multi nodular goiter.
• Hallmark of this category is disturbed architecture – Follicular cells predominantly arranges in micro follicles or trabeculae.
• Cytological preparations typically have high cellularity and scant to absent colloid
• Cellular crowding and overlapping are conspicuous and follicular cells are usually larger than normal
• Nuclear pleomorphism, and mitosis are uncommon
• Cases that demonstrate nuclear features of Papillary carcinoma are excluded from this category
• If sample is cellular and mostly macro follicles benign interpretation is appropriate
Category V (Suspicious for malignancy)
• If only 1 or 2 characteristics of malignancy are present, if they are only focal or if sample is sparsely cellular and a malignant diagnosis cannot be made with certainty
Category VI (Malignant)
• This category is used whenever cytomorphological features are conclusive for malignancy
• Descriptive comments that follow are used to sub classify malignancy and to summarize the results of special studies if any
DIAGNOSTIC CATEGORY RISK OF MALIGNANCY USUAL MANAGEMENT
ND/ UNS 1-4 % Repeat FNA with ultrasound guidance
Benign 0-3 % Clinical Follow up
AUS/ FLUS 5-15% Repeat FNA
FN/ SFN 15-30% Surgical lobectomy
Suspicious for Malignancy 60-75% Near total thyroidectomy / Surgical lobectomy
Malignant 97-99% Near total thyroidectomy
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