Correlation between DNA ploidy, metaphase high-resolution comparative genomic hybridization results and clinical outcome of synovial sarcoma

DNA ploidy was determined on Feulgen-stained smears in 56 synovial sarcoma cases by image cytometry; follow up was available in 46 cases (average: 78 months). In 9 cases HR-CGH analysis was also available.10 cases were found DNA-aneuploid, 46 were DNA-diploid by image cytometry. With fine-tuning of the diploid cases according to the 5c exceeding events (single cell aneuploidy), 33 cases were so called "simple-diploid" (without 5c exceeding events) and 13 cases were "complex-diploid"; containing 5c exceeding events (any number). Aneuploid tumors contained large numbers of genetic alterations with the sum gain of at least 2 chromosomes (A-, B- or C-group) detected by HR-CGH. In the "simple-diploid" cases no or few genetic alterations could be detected, whereas the "complex-diploid" samples numerous aberrations (equal or more than 3) could be found.Our results show a correlation between the DNA-ploidy, a fine-tuned DNA-ploidy and the HR-CGH results. Furthermore, we found significant correlation between the different ploidy groups and the clinical outcome (p < 0.05).Synovial sarcoma (SS) is the 3rd most common mesenchymal spindle cell tumor [1]. It occurs most commonly in the young, representing about 8% of all soft tissue sarcomas but about 15-20% of cases in adolescents and young adults [2]. The peak of incidence is before the 4th decade and males are affected more often than females (ratio around 1.2:1). Almost all SSs are high-grade lesions with a 5-year overall survival rate of 36-76%, depending on the patient's age, the tumor size, the proportion of poorly differentiated areas and the resectability of the tumor. Histologically, two distinct subtypes can be distinguished: a monophasic, containing spindle cells; and a biphasic, containing both an epithelial and a spindle cell component [3]. A rare form of monophasic SS also exists, containing only epithelial-like cells [4]. The monophasic subtype is more common than the biphasic one. SS has a characteristic balanced