Current research on salivary gland pleomorphic adenoma is aimed at grouping the cases by cytogenetical aberrations into several subtypes.
In this report, 21 cases of pleomorphic adenomas were analysed cytogenetically and divided into 4 subtypes following Bullediek's method; normal karyotype (6 cases), 8q12 rearrangement (8 cases), 12q13-15 rearrangement (5 cases) and other aberrations (2 cases).
The average occurrence age of each group was examined. The 8q12 rearrangement group (37.2 y.o.) was younger than the normal karyotype (49.2 y.o.) and 12q13-15 rearrangement groups (52.4 y.o.).
Histological subtyping based on Seifert's classification was made and its relationship with the above cytogenetic subtypes was studied. In the 8q12 rearrangement group, Seifert's type-1 was predominant (88%), while in the normal karyotype and 12r13-15 rearrangement groups, Seifert's type-2 was the most common (50% and 80% respectively).
We also examined 2 cases of carcinoma in pleomorphic adenoma. Although both showed some cytogenetic abnormalities, no aberrations specific to pleomorphic adenoma (8q12 or 12q13-15 rearrangement) were found. This suggests that original adenomas of these carcinomas showed a normal karyotype or other types of aberrations.