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

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.

Reflex fluorescent in situ hybridization testing for unsuccessful product of conception cultures: a retrospective analysis of 5555 samples attempted by conventional cytogenetics and fluorescent in situ hybridization.

INTRODUCTION: The use of chromosome analysis on products of conception from spontaneous abortions is recommended to identify a genetic etiology. However, 20% of products of conception cultures are unsuccessful due to microbial contamination or lack of viable dividing cells. Our laboratory implemented a reflex fluorescent in situ hybridization (FISH) assay to detect numeric chromosome abnormalities for unsuccessful cultures. MATERIALS AND METHODS: All products of conception samples were simultaneously processed for both chromosome analysis and FISH analysis. If the chromosome analysis was unsuccessful, interphase FISH was performed for chromosomes 13, 16, 18, 21, 22, X, and Y. To assess the performance of the FISH assay, a 3-year retrospective comparative analysis of the FISH results versus chromosome results was performed. RESULTS: Of 5555 total specimens, 4189 (75%) represented chorionic villi/fetal tissue and 1366 (25%) represented tissue of unidentified origin. Of the 1189 tissues of unidentified origin with chromosome or FISH results, 1096 (92%) were XX, indicating that the majority of these tissues are likely maternal in origin. Of the 3361 successful chromosome studies on the chorionic villi/fetal tissue specimens, 1734 (52%) samples had a chromosome abnormality. Of the 762 successful FISH studies on chorionic villi/fetal tissue specimens that were unsuccessful by chromosome studies, 181 (25%) had an abnormal result with the targeted FISH panel. Overall, the FISH panel detected approximately 70% of the chromosome abnormalities in products of conception detectable by karyotype. When the FISH panel results were combined with chromosome analysis for the 4189 chorionic villi/fetal tissue specimens, the overall abnormality rate is 47%. CONCLUSIONS: Our reflex FISH assay proved useful for the detection of common chromosome aneuploidies in products of conception samples that failed conventional chromosome analysis. Because of its limited view of the genome, cautious interpretation of FISH results is required for all samples, in particular, trisomy of an acrocentric chromosome, which may represent a Robertsonian translocation. An algorithmic approach to the genetic evaluation of products of conception specimens, with the potential for initial evaluation by a FISH panel, may be warranted.

Isochromosome 12p and polysomy 12 in primary central nervous system germ cell tumors: frequency and association with clinicopathologic features.

Germ cell tumors arising within the central nervous system are rare neoplasms that typically occur along midline structures in children and young adults. Although isochromosome 12p is established as a frequent chromosomal abnormality in testicular germ cell tumors, studies examining isochromosome 12p in primary central nervous system germ cell tumors are limited. Herein, we studied 24 primary central nervous system germ cell tumors from 23 patients using fluorescence in situ hybridization to determine the frequency of isochromosome 12p in these neoplasms. Of the 24 primary central nervous system germ cell tumors, fluorescence in situ hybridization detected isochromosome 12p in 6 (25%) tumors, whereas 11 (46%) tumors showed polysomy (multiple copies) of chromosome 12. One case with isochromosome 12p also showed increased 12p independent of isochromosome 12p formation. The remaining 7 tumors yielded a normal result by fluorescence in situ hybridization. Clinical follow-up of this patient cohort indicated 8 patients (32%) developed a recurrence, although no association was demonstrated between the presence or absence of chromosomal 12 abnormalities and tumor relapse. We confirm that isochromosome 12p is less frequent in primary central nervous system germ cell tumors relative to testicular germ cell tumors, and although our numbers are limited, the presence or absence of isochromosome 12p does not appear to impact tumor recurrence. Similarly, although polysomy 12 was identified in nearly half of our central nervous system germ cell tumors, no prognostic significance was attributed to this abnormality. These results suggest that fluorescence in situ hybridization studies for isochromosome 12p or polysomy 12 may have limited use in the evaluation of these rare neoplasms.

CCND1 rearrangements and cyclin D1 overexpression in renal oncocytomas: frequency, clinicopathologic features, and utility in differentiation from chromophobe renal cell carcinoma.

SUMMARY: Renal oncocytoma is a benign tumor occurring singly or as multiple synchronous lesions. The histologic features of renal oncocytoma may overlap with those of chromophobe renal cell carcinoma. Chromosomal translocations involving the CCND1 locus at 11q13 and overexpression of cyclin D1 occur in a subset of renal oncocytomas. We evaluated a series of 63 renal oncocytomas and 36 chromophobe renal cell carcinomas and assessed the clinical features, cyclin D1 overexpression by immunohistochemistry, and alterations of the CCND1 gene by fluorescence in situ hybridization. All 36 chromophobe renal cell carcinomas were negative for cyclin D1 overexpression and alterations of CCND1. Of the 63 renal oncocytomas, 21 (33%) showed cyclin D1 overexpression. Of 21 renal oncocytomas with cyclin D1 overexpression, a CCND1 rearrangement was detected in 12 (57%). A CCND1 rearrangement was also identified in 1 (2%) of the 42 renal oncocytomas without cyclin D1 overexpression. Of 42 renal oncocytomas without cyclin D1 overexpression, 16 (38%) were from patients with multiple renal oncocytomas at nephrectomy. Of 21 renal oncocytomas with cyclin D1 overexpression, only 1 (5%) patient had multiple renal oncocytomas (P = .006). Of the 25 patients whose original tumor showed no cyclin D1 overexpression, 8 (32%) developed a subsequent renal oncocytoma. None of 15 patients whose original tumor showed cyclin D1 overexpression had a subsequent renal oncocytoma (P = .016). The findings of this study suggest that renal oncocytomas lacking cyclin D1 overexpression may be associated with the development of multiple renal oncocytomas and that these patients are more likely to develop subsequent renal oncocytomas suggesting the need for more frequent clinical for these patients and little need for follow-up in patients with renal oncocytomas overexpressing cyclin D1. The data also show that cyclin D1 overexpression and CCND1 rearrangements by fluorescence in situ hybridization are absent in chromophobe renal cell carcinoma, suggesting that these are useful when differentiating between renal oncocytoma and chromophobe renal cell carcinoma.

Utility of ALK-1 protein expression and ALK rearrangements in distinguishing inflammatory myofibroblastic tumor from malignant spindle cell lesions of the urinary bladder.

Inflammatory myofibroblastic tumor of the urinary bladder is an unusual spindle cell neoplasm that displays cytologic atypia, infiltrative growth and mitotic activity mimicking malignant tumors, such as leiomyosarcoma, rhabdomyosarcoma and sarcomatoid carcinoma. The objective of this study was to determine if anaplastic lymphoma kinase (ALK-1) protein expression detected by immunohistochemistry and ALK rearrangements detected by fluorescence in situ hybridization (FISH) were useful in distinguishing inflammatory myofibroblastic tumor from malignant spindle cell tumors of the urinary bladder. In inflammatory myofibroblastic tumor, ALK-1 expression was identified in 13 of 21 cases (62%) and ALK rearrangements in 14 of 21 cases (67%). All cases of inflammatory myofibroblastic tumor demonstrating ALK-1 expression, carried ALK rearrangements. One case negative for ALK-1 expression exhibited ALK rearrangement. ALK rearrangements were more common in women (P=0.0032). Leiomyosarcoma, sarcomatoid carcinoma, embryonal rhabdomyosarcoma and reactive myofibroblastic proliferations were negative for ALK-1 protein and ALK rearrangements. Immunohistochemistry using markers of muscle, epithelial, neural, and follicular dendritic cell differentiation showed overlap between inflammatory myofibroblastic tumor with and without ALK gene rearrangements, and between inflammatory myofibroblastic tumor and spindle cell malignancies. However, coexpression of cytokeratin and muscle-specific antigens was unique to inflammatory myofibroblastic tumor, observed in approximately half the tumors. This study indicates that detection of ALK protein and ALK gene rearrangements are useful in distinguishing inflammatory myofibroblastic tumor from spindle cell malignancies in the urinary bladder. Additionally, our findings suggest that ALK rearrangement is the primary mechanism for ALK activation and that inflammatory myofibroblastic tumor likely represents a heterogeneous group of spindle cell proliferations with the majority associated with ALK translocations, and the remaining associated with other etiologies.