IMPACT OF THE IN-VITRO TECHNIQUE USED ON THE CYTOGENETIC PATTERNS IN PLEOMORPHIC ADENOMAS

The cytogenetic observations in 97 new cases of pleomorphic adenomas a re reported. They were all studied by in vitro technique using enzymat ic pretreatment of the explanted material. The results, together with 26 previously reported cases studied by the some method (series II), w ere compared with a group of 130 adenomas (series I) investigated in c ultures of only mechanically dispersed material. The results showed th at in series II there was a substantial reduction of normal stemlines, an increase of cases with t(3;8)(p21;q12) and, in particular, of thos e with other 8q12 involvement. There was a similar frequency of cases with 12q13-15 aberrations in both series whereas, in series II, there was a moderate increase of the cases with ''unique'' abnormal stemline s. In comparison the German material, comprising 220 cases also studie d by the enzymatic method, revealed a much higher frequency of cases w ith a normal stemline and a much lower frequency of adenomas with 8q12 -involvement and of cases with unique stemlines. The results emphasize the need and importance of a meticulous documentation of all details of the in vitro technique used, for instance: explantation methods, co mposition of media, growth periods in vitro, and methods of harvest. ( C) Elsevier Science Inc., 1997.