Picture Atlas

FINE NEEDLE ASPIRATION: THYROID

Here are some examples of classical conditions, organised according to categories in The Bethesda System for Reporting Thyroid Cytopathology.

Click on the specific condition to view pic:

Colloid nodule

Flat honeycomb sheets of follicular cells which are evenly spaced showing uniform round nuclei with granular chromatin and scant cytoplasm.
Colloid can appear in the form of a thin, translucent film with bubbles and linear cracks or in the form of thicker blobs.
Macrophages are sometimes present, and, if abundant or accompanied by granular proteinaceous material, indicate cystic change.

Subacute (de Quervain) Thyroiditis

In addition to follicular cells, there are histiocytes, with varying numbers of lymphocytes and/or some neutrophils.
May have poorly formed epithelioid granulomas.
Presence of large multinucleated giant cells containing numerous nuclei is a helpful feature (sometimes these cells engulf colloid).
Note: Smaller multinucleated giant cells are less specific and may be seen in Hashimoto thyroiditis and papillary thyroid carcinoma.

Lymphocytic Thyroiditis

Benign groups of follicular cells and scant colloid.
Follicular cells may show varying proportions of Hurthle cells with round nuclei and abundant granular cytoplasm.
Many lymphocytes in the background – mixed population, predominantly small lymphocytes.
Sometimes germinal centre material may be seen. Sometimes multinucleated giant cells are also seen.

Atypical; Follicular Lesion of Undetermined Significance / Atypia of Undetermined Significance

The FLUS category is a mixed one, covering a spectrum of findings.
There is architectural and/or nuclear atypia; but not to the extent of being suspicious for malignancy.
This is an example of FLUS/AUS with architectural atypia:
- In some areas, the follicular cells show architectural atypia e.g. microfollicles, crowded sheets; while in other areas, some flat sheets are seen.

Atypical; Follicular Lesion of Undetermined Significance / Atypia of Undetermined Significance

The FLUS category is a mixed one, covering a spectrum of findings.
There is architectural and/or nuclear atypia; but not to the extent of being suspicious for malignancy.
This is an example of FLUS/AUS with both architectural and nuclear atypia:
- There are crowded sheets of follicular cells arranged in trabecular formations.
- Nuclear atypia is seen, with enlarged nuclei with occasional nuclear grooves and rare nuclear pseudoinclusions.
- There are insufficient definitive diagnostic features for papillary thyroid carcinoma.

Malignant; Papillary Thyroid Carcinoma

Usually highly cellular aspirates, showing many monolayered syncytial sheets and sometimes papillary structures.
Nuclei overlap each other within the syncytial sheets.
Nuclei are often ovoid and enlarged, with fine powdery chromatin, occasional nuclear grooves and nuclear pseudoinclusions.
Cytoplasm may be delicate or dense.
Thick colloid (“bubble-gum” colloid), which are better appreciated in Romanowsky stains, may be present.
Multinucleated giant cells may be noted in the background.
Sometimes, psammoma bodies may be seen, especially in cystic PTC.