Test Catalog

Test ID: BCOR    
BCOR Immunostain, Technical Component Only

Useful For Suggests clinical disorders or settings where the test may be helpful

Helping in the distinction of a subset of primitive round cell sarcomas with BCOR rearrangements from other Ewing/Ewing-like sarcomas

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For the initial technical component only immunohistochemical (IHC) stain performed, the appropriate bill-only test ID will be reflexed and charged (IHTOI). For each additional technical component only IHC stain performed, an additional bill-only test ID will be reflexed and charged (IHTOA).

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Round cell sarcomas are a heterogeneous group of tumors which have diverse genetic abnormalities, clinical presentations and outcomes despite similar cytomorphology. The diagnosis of these emerging entities has relied on molecular tests until recent immunohistochemical screening markers. BCOR (BCL-6 interacting corepressor) is involved in suppressing gene expression by either interacting with BCL-6 or binding to PCGF1 (poly-comb-group RING finger homologue1) and inducing gene silencing by histone modification. BCOR immunohistochemistry is a highly sensitive marker in identifying round cell sarcomas with BCOR abnormalities.

Interpretation Provides information to assist in interpretation of the test results

This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required order PATHC / Pathology Consultation.


The positive and negative controls are verified as showing appropriate immunoreactivity. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen-dependent. Best practice is for paraffin sections to be cut within 6 weeks.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Machado I, Yoshida A, Lopez-Guerrero JA, et al: Immunohistochemical analysis of NKX2.2, ETV4, and BCOR in a large series of genetically confirmed Ewing sarcoma family of tumors. Pathol Res Pract 2017; 213:1048-1053

2. Chiang S, Lee CH, Stewart CJR, et al: BCOR is a robust diagnostic immunohistochemical marker of genetically diverse high-grade endometrial stromal sarcoma, including tumors exhibiting variant morphology. Mod Pathol 2017; 30:1251-1261

3. Kao YC, Sung YS, Zhang L, et al: BCOR Overexpression Is a Highly Sensitive Marker in Round Cell Sarcomas With BCOR Genetic Abnormalities. Am J Surg Pathol 2016;40(12):1670-1678