Cryptic EWSR1-FLI1 fusions in Ewing sarcoma: potential pitfalls in the diagnostic use of fluorescence in situ hybridization probes.

Detection of EWSR1 translocations - particularly t(11;22)(q24;q12) - is of great value in the differential diagnosis of the Ewing family of tumors. We report two cases that highlight the problems and pitfalls of identifying Ewing tumors using conventional chromosome analysis and a commercial EWSR1 fluorescence in situ hybridization (FISH) probe. In both cases, the tumor karyotype was abnormal, but a visible t(11;22)(q24;q12) was not present.

Correlation of heterogeneity for chromosome 3 copy number with cell type in choroidal melanoma of mixed-cell type.

Purpose: To study heterogeneity for chromosome 3 copy number in mixed choroidal melanoma with discrete populations of spindle and epithelioid cells using chromosome in situ hybridization (CISH) and to correlate chromosomal loss with cell type.

Methods: Twenty-two archival cases of choroidal melanoma with discrete populations of spindle and epithelioid cells were identified. CISH was used to identify chromosome 3 copy number in spindle and epithelioid areas.

Monosomy 3 predicts death but not time until death in choroidal melanoma.

Purpose: To study whether monosomy 3 can predict time until death caused by metastatic melanoma, whether life expectancy can be predicted in patients after surgical excision of a melanoma displaying monosomy 3, and to confirm the prognostic value of monosomy 3 and its correlation with tumor histology.

Methods: Archival specimens from 71 patients who died of metastatic melanoma and 40 patients who were living or had died of other causes were identified. The number of copies of chromosome 3 was assessed by chromosome in situ hybridization, and monosomy 3 was compared with clinicopathologic features.