Chromosomal aberrations in minor salivary gland pleomorphic adenoma

Cytogenetic analysis of a pleomorphic adenoma (PA) arising in the major salivary glands, in particular the parotid, is well documented, with chromosome 8 being the most commonly involved aberration, mainly in t(3;8). However, cytogenetic studies of PA in the minor salivary glands (MSGs) are rare and, to the authors' knowledge, only 3 reports have been published. The authors investigated the cytogenetic abnormalities of a series of 6 PAs arising from MSGs and compared these with published findings from the parotid gland to determine whether the karyotype was the same in the 2 sites.

Six fresh samples of MSG PA were examined by classic cytogenetic analysis. The tissue was minced and cultured in RPMI-1640 medium. The cells were fixed after 2 to 8 days of culture and analyzed according to standard procedures. More than 25 metaphases were analyzed on G-banded slides, and the karyotype was described according to International System for Human Cytogenetic Numenclature guidelines.

The spectrum of chromosomal aberrations found in the MSG PAs was similar to those reported in the major salivary glands in all 6 cases.

Cytogenetically, there would seem to be no clear differences in PAs arising from the major salivary glands versus the MSGs. It is unknown whether the underlying tumorigenesis and chromosomal aberrations of PAs from major salivary glands and MSGs are similar, although the proportion of malignant tumors arising from the MSGs is much larger compared with the parotid. Further studies are needed in this area.