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thyroid Bethesda category 4

Friday 19 August 2016

Thyroid Bethesda class IV


- Predominantly microfollicular smear in thyroid FNA w no colloid. Bethesda Category IV. Class 4.

The aim of Bethesda category 4 is to identify a nodule that might be a follicular carcinoma. Follicular carcinomas have cytomorphologic features that distinguish them from benign follicular nodules but do not permit distinction from a follicular adenoma (FA).

They are reportable as FN or SFN. About 15–30% of these cases called FN/SFN prove to be malignant, the rest being FAs or adenomatoid nodules of MNG.

The criteria for reporting under TBSRTC category IV are :*
- significant alteration in the follicular cell architecture, characterized by cell crowding, micro follicles, dispersed isolated cells and scant or absent colloid.

The criteria for FN Hurthle cell type/suspicious for a FN Hurthle cell type FNHCT/SFNHC (subcategory of TBSRTC IV) are a sample consisting exclusively of hurthle cells, usually little or no colloid or virtually no lymphocytes or plasma cells

TBSRTC recommends lobectomy for this category.

See also

- thyroid FNA

Open references

- The Bethesda System for Reporting Thyroid Cytopathology: Interpretation and Guidelines in Surgical Treatment. Renuka IV et al., 2012. (Open access)