| Cytologic pattern | Description | Histopathology |
| Benign macrofollicular fragments | - Abundant colloid
- Predominantly large follicles and flat sheets of follicular cells
| - Nodular goiter (colloid adenoma)
- Macrofollicular adenoma
|
| Atypia of undetermined significance | | - Nodular goiter (hyperplasia)
- Papillary thyroid cancer
- Follicular variant papillary thyroid cancer
- NIFTP
|
- Architectural atypia: mixed macrofollicles and microfollicles
| - Nodular goiter (including autonomous nodules)
- Follicular neoplasm
- Follicular cancer
- Follicular variant papillary thyroid cancer
- NIFTP
|
- Oncocytic atypia: extensive oncocytic (Hürthle cell) changes
| - Nodular goiter (with degeneration)
- Hashimoto's thyroiditis
- Oncocytic neoplasm
- Oncocytic cancer
|
| Follicular neoplasm (microfollicular) | - Scant colloid
- Small microfollicles
- or
- Clusters and clumps of cells with varying pleomorphism
| - Microfollicular adenoma
- or
- Follicular carcinoma
|
- Cells have intranuclear inclusions and clefts
| - Follicular variant of papillary carcinoma
|
| Oncocytic neoplasm | - Oncocytic (Hürthle cell) changes with nuclear and architectural (microfollicles) atypia
| - Oncocytic adenoma or oncocytic carcinoma
|
