Cytogenomic Abnormalities in 19 Cases of Salivary Gland Tumors of Parotid Gland Origin

Abstract

Salivary gland tumors (SGTs) of parotid origin are a group of diverse neoplasms which are difficult to classify due to their rarity and similar morphologic patterns. Chromosome analysis can detect clonal abnormalities, and array comparative genomic hybridization (aCGH) analysis can define copy number alterations (CNAs) from tumor specimens. Of the 19 cases of various types of SGTs submitted for cytogenomic analyses, an abnormal clone was detected in nine cases (47%), and CNAs were detected in 14 cases (74%). Recurrent rearrangements involving the PLAG1 gene at 8q12, recurrent CNAs including deletions of 6q, 9p (CDKN2A), and 17p (TP53), loss of Y chromosome, and gain of chromosome 7 were defined from these cases. Combined karyotyping and aCGH analyses could improve diagnostic yield. Future study for more precisive correlation of SGT classification with cytogenomic abnormalities will facilitate better diagnosis and treatment.

Figure 1

Cytogenomic abnormalities detected in 19 cases of SGTs. (a) For case 4, representative karyotype showed an abnormal clone with a deletion in the long arm of chromosome 6 and a paracentric inversion in the long arm of chromosome 8 (left); genome view by aCGH showed CNAs of deletions of 6q and 21q and duplications of 1q, 3q, 11p, 21q, and Xp (right, green bar for deletion and red bar for duplication). (b) For case 7, chromosome analysis showed a normal female karyotype (left); aCGH genome view showed numerous CNAs in multiple chromosomes (right). (c) The distribution of CNAs detected from 14 cases.