The concepts in poorly differentiated carcinoma of the thyroid: a review article.

Poorly differentiated carcinomas of the thyroid have evolved over the past half century into a specific entity in the classification of thyroid carcinomas. The need for a consensus diagnostic criteria has been stressed in view of the wide discrepancies and confusion among pathologists and clinicians. This review attempts to understand the concept, the evolution, clarity and validity of the concepts in poorly differentiated carcinomas of the thyroid.