Table 1 Royal College of Pathologists (RCPath) modified British Thyroid association nomenclature and comparison to the Bethesda system for reporting thyroid cytopathology: recommended diagnostic categories (adapted from [11])
RCPath category | Bethesda system | |
|---|---|---|
Thy1 | Non-diagnostic | Virtually acellular specimen |
Other (obscuring blood, clotting artefact, etc.) | ||
Cyst fluid only | ||
Thy2 | Benign non-neoplastic | Consistent with a benign follicular nodule (includes adenomatoid nodule, colloid nodule, etc.) |
Consistent with lymphocytic (Hashimoto) thyroiditis | ||
Consistent with granulomatous (subacute) thyroiditis | ||
Thy3 | Neoplasm possible—atypia/non-diagnostic (Thy 3a) | Atypia of undetermined significance or follicular lesion of undetermined significance |
Neoplasm possible, suggesting follicular neoplasm (Thy 3f) | Follicular neoplasm or suspicious for a follicular neoplasm | |
Thy4 | Suspicious of malignancy | Suspicious (but not diagnostic) of papillary, medullary or anaplastic carcinoma, or lymphoma |
Thy5 | Diagnostic of malignancy | Unequivocal features of papillary, medullary or anaplastic carcinoma, lymphoma or metastatic tumour or other |