## Clinical Context A Bethesda Category III (atypia of undetermined significance / follicular neoplasm) result on FNAC carries a 15–30% risk of malignancy. The nodule is 2.5 cm (>2 cm), which increases suspicion. Repeat FNAC has poor sensitivity and delays diagnosis; observation alone is inappropriate given the size and cytology. ## Management Algorithm for Bethesda III Nodules ```mermaid flowchart TD A[Bethesda III FNAC]:::outcome --> B{Nodule size?}:::decision B -->|< 1 cm| C[Observation + ultrasound]:::action B -->|1-2 cm| D[Consider molecular testing]:::action B -->|> 2 cm| E[Thyroid lobectomy + frozen section]:::action E --> F{Frozen section: malignancy?}:::decision F -->|Yes| G[Completion thyroidectomy + RAI]:::action F -->|No| H[Observe contralateral lobe]:::action ``` ## Key Point: **Thyroid lobectomy with intraoperative frozen section is the gold standard for Bethesda III nodules >2 cm.** This approach: - Provides definitive histology (frozen section) - Allows completion thyroidectomy if malignancy is confirmed - Avoids unnecessary total thyroidectomy if benign - Minimizes morbidity (single-stage surgery if benign) ## High-Yield: **Bethesda Category III carries 15–30% malignancy risk.** Size >2 cm warrants surgical evaluation rather than repeat cytology or observation alone. ## Clinical Pearl: Molecular testing (ThyroSeq, Afirma) can help refine risk in Bethesda III, but in a resource-limited setting or when unavailable, lobectomy with frozen section remains the standard of care in India. 
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