Concurrent Cytogenetic, Interphase Fluorescence In Situ Hybridization and DNA Flow Cytometric Analyses of a Carcinoma Ex-Pleomorphic Adenoma of Parotid Gland

We report the cytogenetic, fluorescence in situ hybridization (FISH), and DNA ploidy analyses of a high grade carcinoma ex-pleomorphic adenoma of the submandibular gland. Our overall combined analyses showed a marked DNA aneuploidy and numerical abnormalities involving all chromosomes. Cytogenetic analysis revealed a near tetraploid modal chromosomal number with tetraploid loss of chromosomes Y, 1, 6, 9, 11, 14, 15, 17, and 19–21 and hypertetraploid gain of chromosomes 7, 8, and 22. The structural abnormalities included der(1;14)(q10;q10),del(6)(q15q34),+del(6)(q15q34),+der(8)t(1;8)(q12;q12.2),der(9;19)(q10;q10),add(14)(p11.2),i(20)(q10),der(21)t(8;21)(q11.2;q22.3),+der(21)t(8;21)(q11.2;q22.3). Interphase FISH of the primary and short-term cultured cells using directly labeled peri-centromeric probes for chromosomes 6–12, 17, 18, and Y resulted in alterations corresponding to the cytogenetic findings. DNA ploidy analysis of both the primary and cultured tumor cells showed a hyperdiploid stemline with DNA indices of 2.6. The results indicate that: (1) marked numerical, structural chromosomal, and DNA content abnormalities are present in this tumor; and (2) alteration at 8q and 6q regions, together with previous results, suggest an association between these events and the development and/or progression of this tumor.