Identification of t(1;19)(q12;p13) and ploidy changes in an ependymosarcoma: a cytogenetic evaluation

Abstract

Gliosarcoma, a recognized subtype of glioblastoma, is a biphasic tumor exhibiting distinct glial and sarcomatous components. Ependymosarcomas are rarer, biphasic ependymal tumors exhibiting sarcomatous change. Genetic abnormalities associated with this curious phenotype are not well understood. We are presenting the first karyotype of ependymosarcoma with identification of a clonal t(1;19)(q12;p13). Fluorescence in situ hybridization (FISH) was performed with a probe set targeting 1q23 and 19p13.3. Although the tumor did not show evidence of t(1;19)(q23;p13.3) by FISH, increased ploidy was a feature of the sarcomatous component. On clinical followup the patient is doing well without evidence of recurrence 55 months after initial resection, and postoperative treatment with irradiation and temozolomide. The significance of the genetic alterations we describe associated with sarcomatoid change in ependymal neoplasms, and ultimately their prognostic relevance, merits further study.

Figure 1. Increased ploidy in sarcomatous component of ependymosarcoma. An ependymosarcoma with distinct ependymal (a) and sarcomatous (b) components was subjected to cytogenetic analysis. Conventional cytogenetics revealed several clonal abnormalities, including a t(1;19)(q12;p13) translocation (arrow) (c). In addition a subset of metaphases demonstrated tetraploidy (d). Dual color FISH studies performed in the ependymal (e) and sarcomatous (f) components demonstrated a lack of PBX1/E2A fusion, but increased ploidy in the sarcomatous component.