Identification of a complex 17q rearrangement in a metanephric stromal tumor

Metanephric stromal tumor is a rare benign entity belonging to the group of metanephric renal tumors in children. Although metanephric stromal tumors can be cured by simple nephrectomy, differential diagnosis based on histopathologic criteria with other pediatric renal tumors requiring aggressive chemotherapy can be difficult. To our knowledge, cytogenetic characterization of metanephric stromal tumor has never been reported. We describe conventional (“R-bands” karyotyping) and molecular [fluorescence in situ hybridization (FISH), multicolor FISH, oligo array-comparative genomic hybridization] cytogenetic examinations of a metanephric stromal tumor in a 3-year-old boy. Cytogenetic analysis revealed a complex homogeneous gain between bands 17q22 and 17q25.3, resulting in partial triplication of the segment between bands 17q22 and 17q24.3, and duplication of the segment between bands 17q24.3 and 17q25.3. Cytogenetic confirmatory studies in metanephric stromal tumors are currently needed to assess 17q22q25.3 gain as a recurring cytogenetic abnormality of metanephric stromal tumors.