Table 3. Classification of thyroid cytology (12).

Finding	Criteria
Inadequate	Material containing few or no thyrocytes from solid or partly liquid nodules (exception: colloid nodules)
Negative	Any or all of the changes found in normal and hyperplastic thyroid glands (follicular adenomas with large- and mid-sized follicles),including regressive changes, cysts, and hemorrhagic (pseudo-)cysts, colloid nodules, and thyroiditis; clinical and/or cytological follow-up are sometimes recommended
Uncertain/histological*, in need of further evaluation*	Changes that are seen in highly cellular adenomas and follicular carcinomas, including oncocytic variants; corresponds to follicular/oncocytic proliferation or neoplasia; moreover, some of the criteria of other types of malignant tumor may be ‧present, e.g., papillary carcinoma
Suspect for (non-follicular) malignancy	Changes highly indicative of malignancy, although not all of the corresponding criteria are met
Positive	Changes meeting the criteria for papillary, medullary, or poorly differentiated thyroid carcinoma, or for other types of cancer

^*two categories in the Bethesda classification (14)