Bizarre parosteal osteochondromatous proliferation

Soft Tissue and Bone Tumours (Who Classification, 5th ed.)

Primary Author(s)*

Kathleen Schieffer, PhD, FACMG

WHO Classification of Disease

Structure	Disease
Book	Soft Tissue and Bone Tumours (5th ed.)
Category	Bone tumours
Family	Chondrogenic tumours
Type	Bizarre parosteal osteochondromatous proliferation
Subtype(s)	N/A

Related Terminology

Acceptable	N/A
Not Recommended	Nora lesion

Gene Rearrangements

Historically, cytogenetic alterations, including t(1;17)(q32;q21) and inv(7)(q22q32), have been described in BPOP. More recent RNA-sequencing studies have identified recurrent fusions generated from these cytogenetic findings. However, only relatively few patients have undergone genomic sequencing and further studies are needed to better understand the recurring fusions described. Additionally, an inv(6)(p25q15) has been described

Driver Gene	Fusion(s) and Common Partner Genes	Molecular Pathogenesis	Typical Chromosomal Alteration(s)	Prevalence -Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
COL1A2	LINC-PINT	Fusion of COL1A2 (variable breakpoints reported in exon 6 and 23) and exon 4 of the LINC-PINT (long intragenic non-coding RNA, NR_110473.1, NR_170176.1).	inv(7)(q22q32)	Recurrent	D	Yes (WHO)	Cytogenetic characterization of BPOP identified a recurrent paracentric inversion on chromosome 7q. A recent RNA-sequencing study identified a fusion of COL1A2::LINC-PINT, which is the product of this inversion. Breakpoints are described for three tumors. The biological mechanism of disease still requires further study.
COL1A1	MIR29B2CHG	Fusion of COL1A1 (NM_000088.3) exon 32 with MIR29B2CHG (microRNA) exon 3.	t(1;17)(q32;q21)	Recurrent	D	Yes (WHO)	Cytogenetic characterization of BPOP identified a recurrent translocation between chromosome 1q32 and 17q21. A recent RNA-sequencing study identified a fusion of COL1A1::MIR29B2CHG, which is the product of this inversion. Breakpoints are described for one tumor. The biological mechanism of disease still requires further study.

Individual Region Genomic Gain/Loss/LOH

None

Chr #	Gain, Loss, Amp, LOH	Minimal Region Cytoband and/or Genomic Coordinates [Genome Build; Size]	Relevant Gene(s)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
N/A	N/A	N/A	N/A	N/A	N/A	N/A

Characteristic Chromosomal or Other Global Mutational Patterns

None

Chromosomal Pattern	Molecular Pathogenesis	Prevalence - Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
N/A	N/A	N/A	N/A	N/A	N/A

Gene Mutations (SNV/INDEL)

COL1A1 loss of function alterations have been described in three cases. Larger studies are needed to confirm the association of this gene with BPOP.

Gene	Genetic Alteration	Tumor Suppressor Gene, Oncogene, Other	Prevalence - Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
N/A	N/A	N/A	N/A	N/A	N/A	N/A

Note: A more extensive list of mutations can be found in cBioportal, COSMIC, and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content.

Epigenomic Alterations

None

Genes and Main Pathways Involved

Recent studies suggest that genes in the collagen pathway may be associated with BPOP.

Gene; Genetic Alteration	Pathway	Pathophysiologic Outcome
COL1A1/2	Collagen	Unclear at this time, additional studies are needed to determine the mechanism of disease for the identified COL1A1/2 fusions and variants

Genetic Diagnostic Testing Methods

1. Fusion testing
   • Targeted sequencing (such as RT-PCR or targeted next-generation sequencing (NGS) panels)
     • For targeted NGS panels, consider if the assay requires both gene partners to be included on the panel or if it is able to identify novel fusions as long as one of the partners is included on the panel
   • Whole transcriptome RNA-sequencing
     • Provides an unbiased approach to fusion calling
2. Fluorescence in situ hybridization (FISH)
   • FISH may be able to detect the t(1;17) translocation
3. Karyotyping
   • Can identify the described cytogenetic findings as well as other aneusomies
4. DNA sequencing
   • Can identify single nucleotide variations and insertion-deletions
   • Can identify unbalanced copy number alterations

Familial Forms

None

Additional Information

None

Links

None

Notes

*Primary authors will typically be those that initially create and complete the content of a page.  If a subsequent user modifies the content and feels the effort put forth is of high enough significance to warrant listing in the authorship section, please contact the Associate Editor or other CCGA representative.  When pages have a major update, the new author will be acknowledged at the beginning of the page, and those who contributed previously will be acknowledged below as a prior author.

Prior Author(s): *Citation of this Page: “Bizarre parosteal osteochondromatous proliferation”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 12/8/2025, https://ccga.io/index.php/STBT5:Bizarre parosteal osteochondromatous proliferation.