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