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BCOR-CCNB3 fusions are frequent in undifferentiated sarcomas of male children.

Peters TL, Kumar V, Polikepahad S, Lin FY, Sarabia SF, Liang Y, Wang WL, Lazar AJ, Doddapaneni H, Chao H, Muzny DM, Wheeler DA, Okcu MF, Plon SE, Hicks MJ, López-Terrada D, Parsons DW, Roy A - Mod. Pathol. (2014)

Bottom Line: RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA.Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells.CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, Texas Children's Hospital, Houston, TX, USA [2] Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.

ABSTRACT
The BCOR-CCNB3 fusion gene, resulting from a chromosome X paracentric inversion, was recently described in translocation-negative 'Ewing-like' sarcomas arising in bone and soft tissue. Genetic subclassification of undifferentiated unclassified sarcomas may potentially offer markers for reproducible diagnosis and substrates for therapy. Using whole transcriptome paired-end RNA sequencing (RNA-seq) we unexpectedly identified BCOR-CCNB3 fusion transcripts in an undifferentiated spindle-cell sarcoma. RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA. Five additional undifferentiated sarcomas with BCOR-CCNB3 fusions were identified in a series of 42 pediatric and adult unclassified sarcomas. Genomic breakpoint analysis demonstrated unique breakpoint locations in each case at the DNA level even though the resulting fusion mRNA was identical in all cases. All patients with BCOR-CCNB3 sarcoma were males diagnosed in mid childhood (7-13 years of age). Tumors were equally distributed between axial and extra-axial locations. Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells. CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples. An RT-PCR assay developed to detect the fusion transcript in archival formalin-fixed tissue was positive in all six cases, with high sensitivity and specificity in both pre- and post-treated samples. This study adds to recent reports on the clinicopathologic spectrum of BCOR-CCNB3 fusion-positive sarcomas, a newly emerging entity within the undifferentiated unclassified sarcoma category and describes a simple RT-PCR assay that in conjunction with CCNB3 immunohistochemistry can be useful in diagnosing these tumors.

No MeSH data available.


Related in: MedlinePlus

Histological features of BCOR-CCNB3 positive sarcomas. (a) and (b) Spindle cell neoplasm (T290) in a myxoid to edematous matrix with more ovoid cells in (b). (c) Undifferentiated sarcoma (T151) with angulated and ovoid cells. (d-f) Pre-treatment (d, e) and the post-treatment relapsed specimen (f) from T150 shows angulated, spindle, and round cells with similar morphology. (g-h) The pre-treatment sample (g) for T149 shows similar features compared to the post-treatment relapse (h) after 8 years off therapy (arrowheads scattered mitoses). (i) T236 with histologic features of undifferentiated sarcoma similar to the other BCOR-CCNB3 cases. Scale bars, 100 um.
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Figure 3: Histological features of BCOR-CCNB3 positive sarcomas. (a) and (b) Spindle cell neoplasm (T290) in a myxoid to edematous matrix with more ovoid cells in (b). (c) Undifferentiated sarcoma (T151) with angulated and ovoid cells. (d-f) Pre-treatment (d, e) and the post-treatment relapsed specimen (f) from T150 shows angulated, spindle, and round cells with similar morphology. (g-h) The pre-treatment sample (g) for T149 shows similar features compared to the post-treatment relapse (h) after 8 years off therapy (arrowheads scattered mitoses). (i) T236 with histologic features of undifferentiated sarcoma similar to the other BCOR-CCNB3 cases. Scale bars, 100 um.

Mentions: A review of the pre-treatment diagnostic biopsy specimens from the six BCOR-CCNB3 positive cases showed tumors of variable cellularity (Figure 3). The tumors were comprised of areas with high cellularity alternating with less cellular areas in which discohesive neoplastic cells were embedded, often in an edematous and myxoid stroma containing occasionally angulated thin-walled vessels. The original diagnosis for two tumors was spindle cell sarcoma and spindle cell neoplasm (T107 and T290, respectively); both tumors contained areas with a prominent spindle cell pattern and in the case of T107, were arranged in a vague fascicular architecture. The other BCOR-CCNB3 positive tumors were composed of tumor cells with variable nuclear features and included spindled, angulated and ovoid cells overlapping with areas of round cell morphology (Figure 3). Tumor cells had scant to moderate amounts of eosinophilic cytoplasm, and irregular nuclear contours. Nuclei were vesicular with finely dispersed chromatin and occasional indistinct to small nucleoli (as in case T290). None of the tumors showed bizarre nuclear pleomorphism that would be more compatible with a diagnosis of undifferentiated pleomorphic sarcoma. Areas of necrosis were seen in three tumors, ranging from focal to 50% of the tumor area. Mitotic activity, except for T290, was often brisk in the pre-treatment tumors (Table 1), with a median of 30 mitoses per 10 high-power fields (range 1-40).


BCOR-CCNB3 fusions are frequent in undifferentiated sarcomas of male children.

Peters TL, Kumar V, Polikepahad S, Lin FY, Sarabia SF, Liang Y, Wang WL, Lazar AJ, Doddapaneni H, Chao H, Muzny DM, Wheeler DA, Okcu MF, Plon SE, Hicks MJ, López-Terrada D, Parsons DW, Roy A - Mod. Pathol. (2014)

Histological features of BCOR-CCNB3 positive sarcomas. (a) and (b) Spindle cell neoplasm (T290) in a myxoid to edematous matrix with more ovoid cells in (b). (c) Undifferentiated sarcoma (T151) with angulated and ovoid cells. (d-f) Pre-treatment (d, e) and the post-treatment relapsed specimen (f) from T150 shows angulated, spindle, and round cells with similar morphology. (g-h) The pre-treatment sample (g) for T149 shows similar features compared to the post-treatment relapse (h) after 8 years off therapy (arrowheads scattered mitoses). (i) T236 with histologic features of undifferentiated sarcoma similar to the other BCOR-CCNB3 cases. Scale bars, 100 um.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385430&req=5

Figure 3: Histological features of BCOR-CCNB3 positive sarcomas. (a) and (b) Spindle cell neoplasm (T290) in a myxoid to edematous matrix with more ovoid cells in (b). (c) Undifferentiated sarcoma (T151) with angulated and ovoid cells. (d-f) Pre-treatment (d, e) and the post-treatment relapsed specimen (f) from T150 shows angulated, spindle, and round cells with similar morphology. (g-h) The pre-treatment sample (g) for T149 shows similar features compared to the post-treatment relapse (h) after 8 years off therapy (arrowheads scattered mitoses). (i) T236 with histologic features of undifferentiated sarcoma similar to the other BCOR-CCNB3 cases. Scale bars, 100 um.
Mentions: A review of the pre-treatment diagnostic biopsy specimens from the six BCOR-CCNB3 positive cases showed tumors of variable cellularity (Figure 3). The tumors were comprised of areas with high cellularity alternating with less cellular areas in which discohesive neoplastic cells were embedded, often in an edematous and myxoid stroma containing occasionally angulated thin-walled vessels. The original diagnosis for two tumors was spindle cell sarcoma and spindle cell neoplasm (T107 and T290, respectively); both tumors contained areas with a prominent spindle cell pattern and in the case of T107, were arranged in a vague fascicular architecture. The other BCOR-CCNB3 positive tumors were composed of tumor cells with variable nuclear features and included spindled, angulated and ovoid cells overlapping with areas of round cell morphology (Figure 3). Tumor cells had scant to moderate amounts of eosinophilic cytoplasm, and irregular nuclear contours. Nuclei were vesicular with finely dispersed chromatin and occasional indistinct to small nucleoli (as in case T290). None of the tumors showed bizarre nuclear pleomorphism that would be more compatible with a diagnosis of undifferentiated pleomorphic sarcoma. Areas of necrosis were seen in three tumors, ranging from focal to 50% of the tumor area. Mitotic activity, except for T290, was often brisk in the pre-treatment tumors (Table 1), with a median of 30 mitoses per 10 high-power fields (range 1-40).

Bottom Line: RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA.Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells.CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, Texas Children's Hospital, Houston, TX, USA [2] Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.

ABSTRACT
The BCOR-CCNB3 fusion gene, resulting from a chromosome X paracentric inversion, was recently described in translocation-negative 'Ewing-like' sarcomas arising in bone and soft tissue. Genetic subclassification of undifferentiated unclassified sarcomas may potentially offer markers for reproducible diagnosis and substrates for therapy. Using whole transcriptome paired-end RNA sequencing (RNA-seq) we unexpectedly identified BCOR-CCNB3 fusion transcripts in an undifferentiated spindle-cell sarcoma. RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA. Five additional undifferentiated sarcomas with BCOR-CCNB3 fusions were identified in a series of 42 pediatric and adult unclassified sarcomas. Genomic breakpoint analysis demonstrated unique breakpoint locations in each case at the DNA level even though the resulting fusion mRNA was identical in all cases. All patients with BCOR-CCNB3 sarcoma were males diagnosed in mid childhood (7-13 years of age). Tumors were equally distributed between axial and extra-axial locations. Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells. CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples. An RT-PCR assay developed to detect the fusion transcript in archival formalin-fixed tissue was positive in all six cases, with high sensitivity and specificity in both pre- and post-treated samples. This study adds to recent reports on the clinicopathologic spectrum of BCOR-CCNB3 fusion-positive sarcomas, a newly emerging entity within the undifferentiated unclassified sarcoma category and describes a simple RT-PCR assay that in conjunction with CCNB3 immunohistochemistry can be useful in diagnosing these tumors.

No MeSH data available.


Related in: MedlinePlus