ERG expression in chondrogenic bone and soft tissue tumours.
OBJECTIVE
We studied ERG expression in a large series of chondrogenic bone and soft tissue tumours to assess the value of ERG as a possible marker of chondroid/cartilaginous differentiation.


METHODS
Formalin-fixed, paraffin-embedded whole sections from 111 bone and soft tissue tumours with chondroid differentiation or a morphology that may mimic cartilaginous differentiation were retrieved. Immunohistochemistry was performed using anti-ERG monoclonal antibody directed against the N terminus. Nuclear staining was scored as negative (<5%), 1+ (5%-25%), 2+ (26%-50%), 3+ (>51%).


RESULTS
Nuclear ERG expression was seen in all cases of soft tissue chondroma (8), chondromyxoid fibroma (7), chondroblastic osteosarcoma (6) and clear cell chondrosarcoma (1). 10/12 conventional chondrosarcomas were also positive for ERG. In cases of dedifferentiated chondrosarcoma, the well-differentiated component was positive in 7/9 cases, while all dedifferentiated foci were negative. In cases of mesenchymal chondrosarcoma, the hyaline cartilage component was positive in 2/4 cases, whereas the primitive component in all cases was negative. Variable positivity was identified in extraskeletal myxoid chondrosarcomas (4/9), chondroblastomas (3/8) and mixed tumours/myoepitheliomas (2/11). Only 1/12 chordoma was positive for ERG (1+). Interestingly, 15/17 enchondromas were negative for ERG.


CONCLUSIONS
In this study, we further characterise the expression of ERG in mesenchymal tumours and found relatively constant nuclear ERG expression in selected chondrogenic tumours including conventional chondrosarcoma, chondromyxoid fibroma, chondroblastic osteosarcoma and clear cell chondrosarcoma. We also show that ERG may be a helpful ancillary tool in certain select diagnostic scenarios and that awareness of ERG expression in tumours with cartilaginous differentiation is important.
Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, USA.
Wonwoo
W
Shon
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
Andrew L
AL
Folpe
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
Karen J
KJ
Fritchie
D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D001842:Bone and Bones / Q000737:chemistry* / Q000473:pathology; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000737:chemistry / Q000473:pathology; D020219:Chondrogenesis; D002812:Chondroma / Q000737:chemistry / Q000473:pathology; D002813:Chondrosarcoma / Q000737:chemistry / Q000473:pathology; D005350:Fibroma / Q000737:chemistry / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D018204:Neoplasms, Connective and Soft Tissue / Q000737:chemistry* / Q000473:pathology; D012516:Osteosarcoma / Q000737:chemistry / Q000473:pathology; D011237:Predictive Value of Tests; D015534:Trans-Activators / Q000032:analysis*; D000071230:Transcriptional Regulator ERG
D014408:Biomarkers, Tumor; C072312:ERG protein, human; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG
BONE TUMOUR PATHOLOGY; IMMUNOHISTOCHEMISTRY; SOFT TISSUE TUMOURS