fire-flare appearanceA term referring to the light microscopic appearance of colloid at the edge of thyroid follicles which has been fancifully likened to flickering flames. The pattern is best appreciated in Giemsa-stained fine-needle aspiration (FNA) smears from thyroid aspirates. It was first described as a distinctive feature of thyrotoxic goiter and hyperthyroidism, but later found in non-neoplastic (e.g., Graves’ disease) and neoplastic thyroid lesions. Scattered reports to the contrary, marginal vacuoles probably have little diagnostic utility.
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