A Novel Variant Rearrangement of the Rare Aberration dic(17;20)(p11.2;q11.2) Characterized by Array-CGH as an Insertion in a Patient with Myelodysplastic Syndrome of Multilineage Dysplasia (MDS-MLD).

We report on a novel variant of the dicentric chromosome 17;20 (dic (17;20)(p11.2;q11.2) in a patient with de novo myelodysplastic syndrome (MDS). Based on FISH and array-CGH, the variant turns out to be an insertion of chromosome 17 (17p11.2-telomere 17) into chromosome 20 with breakpoints at 20q11.22 and 20q13.33. Based on conventional chromosome analysis and G-banding patterns, the region 17p11.2-17q25 was directly inserted between 20q11.22 and 20q13.33. The breakpoint junctions occurred within KCNJ12 (17p11.2), UQCC1 (20q11.2), and CDH4 (20q13.3), leading to 5' deletions of all the genes and positioning the 3' of UQCC1 next to KCNJ12 at 17p11.2 and CDH4 next to an unknown gene at 17q25-20q13.3. In addition, the centromere of chromosome 17 was not active, transforming the primary constriction to a flat band. Therefore, the novel insertion variant is a pseudo dicentric derivative chromosome with one functional centromere: 45,XX,der(17;20)del(20)(q11.22q13.33)ins(20;17)(q11.2;p11.2q25). A review of the literature of all dic(17;20) cases is presented. For the first time, we report an array-CGH characterization of such rare variant that revealed to be an insertion.

Instability of isochromosome 4p in a child with pure trisomy 4p syndrome features and entire 4q-arm translocation.

Constitutional chromosome instability so far has mainly been associated with ring formation. In addition, isochromosome formation involving the short arm with translocation of the entire long arm is rarely observed. This type of rearrangement has been reported for chromosomes 4, 5, 7, 9, 10, 12, and 20. Here, we present the third patient having an isochromosome 4p with 4q translocation, but showing for the first time chromosome instability detected by FISH following chromosome microarray analysis.

Deceptively benign low-grade fibromyxoid sarcoma: array-comparative genomic hybridization decodes the diagnosis.

Low-grade fibromyxoid sarcoma (previously known as Evans tumor) is a rare soft tissue neoplasm characterized by a deceptively bland appearance despite the potential for late metastasis or recurrence. We describe a 13-year-old patient with a popliteal fossa mass initially thought to be benign that, because of array-comparative genomic hybridization findings and subsequent immunohistochemistry, was diagnosed as low-grade fibromyxoid sarcoma. The array-comparative genomic hybridization demonstrated a loss of 11p11.2p15.5 and a gain of 16p11.2p13.3 with breakpoints involving the CREB3L1 (cAMP responsive element-binding protein 3-like 1) and FUS (fused in sarcoma) genes, respectively. Subsequent fluorescence in situ hybridization analysis of a dual-labeled break-apart FUS probe on interphase cells was positive. Our case highlights the importance of using genetic information obtained via array-comparative genomic hybridization to classify accurately pediatric soft tissue tumors.