fire-flare appearance

fire-flare appearance

A 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.