<prompt> Thyroid condition which cannot be diagnosed by FNAC isThyroiditisMedullary carcinomaLymphomaFollicular carcinoma  <response>: Ans. is d i.e., Follicular carcinoma Fine-needle aspiration cytology FNAC is the investigation of choice in discrete thyroid swellings. FNAC has excellent patient compliance, is simple and quick to perform in the out-patient department and is readily repeated. Thyroid conditions that may be diagnosed by FNAC include colloid nodules, thyroiditis, papillary carcinoma, medullary carcinoma, anaplastic carcinoma and lymphoma. FNAC cannot distinguish between a benign follicular adenoma and follicular carcinoma, as this distinction is dependent not on cytology but on histological criteria, which include capsular and vascular invasion. 