RT Journal Article SR Electronic T1 Diagnostic utility of ERG immunostaining in dermatofibroma JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP jclinpath-2022-208158 DO 10.1136/jclinpath-2022-208158 A1 Yuichi Yamada A1 Toshio Ichiki A1 Yosuke Susuki A1 Yui Yamada-Nozaki A1 Yuki Tateishi A1 Masutaka Furue A1 Yoshinao Oda YR 2022 UL http://jcp.bmj.com/content/early/2022/03/21/jclinpath-2022-208158.abstract AB Aims Dermatofibroma/fibrous histiocytoma (DF/FH) is a common cutaneous mesenchymal neoplasm exhibiting benign biological behaviour. However, the immunohistochemical utility of erythroblast transformation-specific-related gene (ERG) for diagnosing DF remains unknown. The authors reviewed the immunohistochemical status of ERG in different subtypes of DF and in its differential diagnoses.Methods Overall, 97 cases of ordinary DF/FH, 6 cases of aneurysmal FH, 10 cases of cellular FH, 5 cases of angiomatoid FH, 2 cases of epithelioid FH, 64 cases of dermatofibrosarcoma protuberans (DFSP) and 52 cases of fibrous scar were retrieved. As the other histological types of cutaneous neoplasms, 6 cases of myxofibrosarcoma, 4 cases of undifferentiated pleomorphic sarcoma, 11 cases of atypical fibroxanthoma, 19 cases of malignant melanoma, 20 cases of nevocellular nevus, 20 cases of neurofibroma, 19 cases of schwannoma, 8 cases of angioleiomyoma and 1 case of pilar leiomyoma were included.Results Immunohistochemical positivity for ERG was demonstrated in 87 of 97 cases (89.6%) of ordinary DF/FH, 7 of 10 cases (70%) of cellular FH, 3 of 6 cases (50%) of aneurysmal FH, 1 of 5 cases (20%) of angiomatoid FH and 1 of 52 cases (0.1%) of fibrous scar. All cases of DFSP, epithelioid FH and other types of cutaneous neoplasms included in the current investigation were negative for ERG. The intensity of ERG immunohistochemical staining in spindle-shaped cells appeared weaker than that in endothelial cells.Conclusions DF/FH was frequently positive for ERG immunostaining. ERG immunostaining may thus be useful to distinguish DF/FH from DFSP.No data are available.