[Differentiated thyroid carcinoma of follicular origin: new data in 1988]

The problems raised by the histologic diagnosis and prognostic evaluation of differentiated thyroid carcinomas developed from follicles (DTCs) have significantly changed over recent years, partly as a result of the development of medical data processing and immunodetection techniques. From the body of current data, the following fundamental points emerge. First, the importance of factors that influence the course of these tumors can be accurately assessed only through computer-performed multifactorial statistic studies. The main prognostic factors include age, tumor spread at the time of diagnosis, and histologic features. Essential histologic features include demarcation of tumors and degree of differentiation. Second, differential diagnosis between papillary and follicular carcinomas, based primarily on cytologic criteria, may prove difficult. The usefulness of this distinction is even challenged occasionally. The value of cytokeratin immunodetection for distinguishing these two tumor types is discussed. Third, it may be impossible to ascertain the malignity of highly differentiated follicular tumors. No truly significant marker for malignity has been identified to date. The decision must therefore be reached by the cautious use of histologic criteria, including cytologic and architectural features, none of which is diagnostic per se.