Cryptic insertion of 3'FOXO1 into inverted chromosome arm 2q in the presence of two normal chromosome 13s and 13 small interstitial duplications in a patient with alveolar rhabdomyosarcoma.

Alveolar rhabdomyosarcoma (ARMS) is a pediatric soft tissue neoplasm with a characteristic translocation, t(2;13)(q35;q14), which is detected in 70-80% of cases. This well-described translocation produces the gene fusion product PAX3-FOXO1. Cryptic rearrangements of this fusion have never before been reported in ARMS. Here we describe a patient with ARMS that showed, by fluorescence in situ hybridization and G-banded chromosomes, a cryptic insertion of 3'FOXO1 into inverted chromosome 2q. The inversion breakpoints were depicted by array comparative genomic hybridization as two small interstitial duplications, one of which involved the PAX3 gene. In addition, the array comparative genomic hybridization results revealed 1q gain, 16q loss, and 11 more small duplications, with one of them involving the FOXO1 gene. Although the pathogenesis in classic ARMS cases is thought to be driven by the 5'PAX3-3'FOXO1 fusion on derivative chromosome 13, here we report a novel cryptic insertion of 3'FOXO1 resulting in a pathogenic fusion with 5'PAX3 on inverted chromosome 2q.

Narrowing down the common deleted region of 5q to 6.0 Mb in blastic plasmacytoid dendritic cell neoplasms.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy. Simple and complex recurrent cytogenetic abnormalities have been reported, which demonstrate predominantly genomic losses, of which deletions of 5q are the most frequent aberrations in BPDCN with or without cutaneous manifestation; however, the gene responsible for the disease remains unknown. Using microarray-based molecular characterization, a recent study on several cases of BPDCN with the 5q deletion identified a large, common deleted region (CDR) of 29 Mb that contains several possible candidate genes. We report on a 67-year-old female patient who presented with leukemic BPDCN without skin involvement and had a deletion of 5q and a t(6;8)(p21;q24). By oligo-array-comparative genome hybridization (a-CGH) method, the genomic coordinations of the 5q deletion demonstrated unique breakpoints reported for the first time. Through mapping with those published cases using the same a-CGH method, the CDR was reduced from 29 Mb to 6 Mb, which excluded the previous candidate genes and highlighted an excellent biological gene: the HINT1 gene. Moreover, a molecular cytogenetic characterization of the translocation t(6;8) was performed in search for a novel gene fusion that could be associated with tumor progression.

Oculo-auriculo-vertebral spectrum, cat eye, and distal 22q11 microdeletion syndromes: a unique double rearrangement.

An array-CGH on 19-year-old male showed a proximal 1.11 Mb duplication and a distal 1.7 Mb deletion of 22q11.2 regions flanking the Velocardiofacial/DiGeorge syndrome region that remained intact. FISH analyses revealed both abnormalities to be on the same homolog 22. This double rearrangement lead to the co-existence of two syndromes: Cat eye and distal 22q11.2 microdeletion syndromes with a rare associated phenotype of oculo-auriculo-vertebral spectrum (OAVS). A review of the literature indicates that this is the second report of a proximal duplication and the fifth report of a distal deletion and OAVS suggestive of a possible OAVS candidate gene in this region.

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.

Coexistence of neocentromeric marker 3q and trisomy 3 in two different tissues in a 3-year-old boy with peripheral T-cell lymphoma: support for a gene dosage effect hypothesis.

A very small supernumerary de novo marker chromosome was ascertained during cytogenetic diagnosis of a 3 1/2-year-old boy with peripheral T-cell lymphoma, unspecified. The marker, which was C-band and alpha-satellite DNA negative, was identified in the pleural effusion and involved cervical lymph node whereas the involved bone marrow cells had trisomy 3 as a clone. The neocentromere marker was characterized by multiple probes demonstrating an inversion duplication of the distal portion of chromosome 3q involving the BCL6 gene. Whole or partial trisomy 3q represents one of the most recurrent chromosomal abnormalities occurring in T-cell lymphomas, suggesting that the 3q contains a critical region for the pathogenesis of T-cell lymphoma. Our present case showed that the critical region may reside within the neocentromere marker 3q27~q29 in this case in particular and revealed a different mechanism in increasing gene dosage rather than gene disruption. In addition, this type of neocentromere is one most often reported in constitutional cases. Here, we report its presence in cancer for the first time.

Deletion of MYC and presence of double minutes with MYC amplification in a morphologic acute promyelocytic leukemia-like case lacking RARA rearrangement: could early exclusion of double-minute chromosomes be a prognostic factor?

Gene amplification on double minutes is rarely found in acute myeloid leukemia (AML) and is often linked to poor prognosis. It is often associated with acute myeloid leukemia with differentiation (AML-M2) and is rarely reported in acute promyelocytic leukemia (APL), which is characterized in the vast majority of cases by the reciprocal t(15;17)(q22;q21) with resultant translation of an abnormal PML-RARA fusion protein. Most of the rare cases of APL that lack this translocation have a demonstrable RARA breakpoint. We report on a morphologic APL-like case lacking t(15;17) and the RARA breakpoint and also has the deletion MYC of 8q24 associated with the occurrence of MYC amplification on double-minute chromosomes (dmin). Excessive exclusion of dmin was observed at the initial diagnosis. These findings are compared to the few cases previously reported in the literature.