The diagnosis of Ewing sarcoma can be challenging, particularly when the tumor is present in an atypical location and resembles histologic mimics. The hallmark feature of Ewing sarcoma is chromosomal translocation, t(11;22)(q24;q12), involving EWSR1 and ETS gene family members. For decades, fluorescence in situ hybridization with a break-apart EWSR1 probe has been the diagnostic gold standard. However, EWSR1 rearrangements have been identified in other malignancies; thus, the detection of chimeric EWSR1 transcripts has become a preferable approach. Occasionally, insufficient tissue, severe RNA degradation, or economic constraints hamper molecular testing. This study evaluated Protein Kinase C Beta II (PKC β II) expression in >1000 tumors and assessed the utility of PKC β II immunohistochemistry in the differential diagnosis of Ewing sarcoma. Tumors harboring EWSR1 :: FLI1 (n=26), EWSR1 :: ERG , EWSR1 :: ETV4 (n=1), and FUS :: ERG (n=6) fusions were evaluated, revealing strong diffuse immunoreactivity, although a patchy pattern was seen in 3 cases. Undifferentiated round cell sarcomas (n=46), including BCOR -, CIC -, NFATC2 -, NUTM1 -, and PATZ1 rearranged/fusion-sarcomas were negative. Two of the 130 synovial sarcomas, including 1 with a poorly differentiated morphology, showed diffuse, moderate-to-strong positivity. One of the 26 poorly differentiated carcinomas from the head and neck region, probably small cell lung carcinoma metastasis, showed strong PKC β II expression. Neuroblastomas (>50%) expressed PKC β II, although none showed a strong diffuse pattern. Diffuse moderate-to-strong immunoreactivity was observed in 2 sarcomatoid mesotheliomas and 2 metastatic melanomas. Diffuse but weak staining was observed in 73% (11/15) of the T-cell lymphoblastic lymphomas, including 10 CD99-positive cases. Similarly, weak predominantly patchy staining was seen in half (40/80) of other non-Hodgkin lymphomas and sporadically in embryonal rhabdomyosarcoma, Merkel cell carcinoma, small cell lung carcinoma, and Wilms tumor. Thus, diffuse and strong PKC β II immunoreactivity appears to be a reliable diagnostic marker for distinguishing classic Ewing sarcoma from histologic mimics.

Bioptická Laboratoř Ltd Pilsen

Department of Clinical and Experimental Pathology Wrocław Medical University Wrocław

Department of Molecular Diagnostics Holycross Cancer Center Kielce Poland

Department of Pathobiology Institut Bergonié Comprehensive Cancer Center Bordeaux France

Department of Pathology Faculty of Medicine in Plzen University Hospital Plzen Charles University Plzen Czech Republic

Department of Pathology Stanford University School of Medicine Stanford CA

Department of Pathology University Hospital of the Canary Islands San Cristóbal de La Laguna Santa Cruz de Tenerife Spain

Department of Tumor Pathology Maria Skłodowska Curie National Research Institute of Oncology Cracow Branch Krakow Poland

Laboratory of Pathology National Cancer Institute Bethesda MD

Zobrazit více v PubMed

Ewing J. Diffuse endothelioma of bone. Proc New York Pathol Soc. 1921;12:17.

Stout AP. A tumor of the ulnar nerve. Proc NY Pathol Soc. 1918;18:2–12.

Askin FB, Rosai J, Sibley RK, et al. Malignant small cell tumor of the thoracopulmonary region in childhood: a distinctive clinicopathologic entity of uncertain histogenesis. Cancer. 1979;43:2438–2451.

Aurias A, Rimbaut C, Buffe D, et al. Translocation involving chromosome 22 in Ewing’s sarcoma. A cytogenetic study of four fresh tumors. Cancer Genet Cytogenet. 1984;12:21–25.

Whang-Peng J, Triche TJ, Knutsen T, et al. Cytogenetic characterization of selected small round cell tumors of childhood. Cancer Genet Cytogenet. 1986;21:185–208.

Downing JR, Head DR, Parham DM, et al. Detection of the (11;22)(q24;q12) translocation of Ewing’s sarcoma and peripheral neuroectodermal tumor by reverse transcription polymerase chain reaction. Am J Pathol. 1993;143:1294–1300.

Delattre O, Zucman J, Plougastel B, et al. Gene fusion with an ETS DNA-binding domain caused by chromosome translocation in human tumours. Nature. 1992;359:162–165.

Zhang L, Lemarchandel V, Romeo PH, et al. The Fli-1 proto-oncogene, involved in erythroleukemia and Ewing’s sarcoma, encodes a transcriptional activator with DNA-binding specificities distinct from other Ets family members. Oncogene. 1993;8:1621–1630.

Burchill SA. Ewing’s sarcoma: diagnostic, prognostic, and therapeutic implications of molecular abnormalities. J Clin Pathol. 2003;56:96–102.

Hung YP, Fletcher CD, Hornick JL. Evaluation of NKX2-2 expression in round cell sarcomas and other tumors with EWSR1 rearrangement: imperfect specificity for Ewing sarcoma. Mod Pathol. 2016;29:370–380.

Machado I, Yoshida A, López-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.

Russell-Goldman E, Hornick JL, Qian X, et al. NKX2.2 immunohistochemistry in the distinction of Ewing sarcoma from cytomorphologic mimics: diagnostic utility and pitfalls. Cancer Cytopathol. 2018;126:942–949.

Zota V, Siegal GP, Kelly D, et al. Validation of PRKCB immunohistochemistry as a biomarker for the diagnosis of Ewing sarcoma. Fetal Pediatr Pathol. 2023;42:241–252.

The WHO Classification of Tumours Editorial Board. WHO Classification of Tumours Soft Tissue and Bone Tumours, 5th ed.. Lyon: IARC Press; 2020.

Kaczorowski M, Chłopek M, Kruczak A, et al. PRAME expression in cancer. A Systematic immunohistochemical study of >5800 epithelial and nonepithelial tumors. Am J Surg Pathol. 2022;46:1467–1476.

Kawakami T, Kawakami Y, Kitaura J. Protein kinase C beta (PKC beta): normal functions and diseases. J Biochem. 2002;132:677–682.

Surdez D, Benetkiewicz M, Perrin V, et al. Targeting the EWSR1-FLI1 oncogene-induced protein kinase PKC-β abolishes Ewing sarcoma growth. Cancer Res. 2012;72:4494–4503.

Sharrocks AD. The ETS-domain transcription factor family. Nat Rev Mol Cell Biol. 2001;2:827–837.

Baranov E, McBride MJ, Bellizzi AM, et al. A novel SS18-SSX fusion-specific antibody for the diagnosis of synovial sarcoma. Am J Surg Pathol. 2020;44:922–933.

Zaborowski M, Vargas AC, Pulvers J, et al. When used together SS18-SSX fusion-specific and SSX C-terminus immunohistochemistry are highly specific and sensitive for the diagnosis of synovial sarcoma and can replace FISH or molecular testing in most cases. Histopathology. 2020;77:588–600.

Lasota J, Chłopek M, Kaczorowski M, et al. Utility of immunohistochemistry with antibodies to SS18-SSX chimeric proteins and C-terminus of SSX protein for synovial sarcoma differential diagnosis. Am J Surg Pathol. 2024;48:97–105.

Folpe AL, Goldblum JR, Rubin BP, et al. Morphologic and immunophenotypic diversity in Ewing family tumors: a study of 66 genetically confirmed cases. Am J Surg Pathol. 2005;29:1025–1033.

Machado I, Navarro S, López-Guerrero JA, et al. Neuroendocrine differentiation in a large series of genetically-confirmed Ewing’s sarcoma family tumor: does it provide any diagnostic or prognostic information? Pathol Res Pract. 2021;219:153362.

Möller K, Gulzar T, Lennartz M, et al. TTF-1 is a highly sensitive but not fully specific marker for pulmonary and thyroidal cancer: a tissue microarray study evaluating more than 17,000 tumors from 152 different tumor entities. Virchows Arch. 2024;485:815–828.

Stransky N, Cerami E, Schalm S, et al. The landscape of kinase fusions in cancer. Nat Commun. 2014;5:4846.

de la Fouchardière A, Pissaloux D, Houlier A, et al. Histologic and genetic features of 51 melanocytic neoplasms with protein kinase C fusion genes. Mod Pathol. 2023;36:100286.

Patel P, Chen A, Sharma N, et al. PRKC fusion melanocytic tumors, a subgroup of melanocytic tumors more closely aligned to blue nevi than to PRKAR1A-inactivated pigmented epithelioid melanocytomas. Am J Surg Pathol. 2024;48:1349–1358.

Aquino A, Bianchi N, Terrazzan A, et al. Protein kinase C at the crossroad of mutations, cancer, targeted therapy and immune response. Biology (Basel). 2023;12:1047.

Kawano T, Inokuchi J, Eto M, et al. Activators and inhibitors of protein kinase C (PKC): their applications in clinical trials. Pharmaceutics. 2021;13:1748.

Piperno-Neumann S, Carlino MS, Boni V, et al. A phase I trial of LXS196, a protein kinase C (PKC) inhibitor, for metastatic uveal melanoma. Br J Cancer. 2023;128:1040–1051.

Stahl M, Ranft A, Paulussen M, et al. Risk of recurrence and survival after relapse in patients with Ewing sarcoma. Pediatr Blood Cancer. 2011;57:549–553.

Muhowski EM, Lehman AM, Reiff SD, et al. The protein kinase C inhibitor MS-553 for the treatment of chronic lymphocytic leukemia. Blood. 2019;134:2077.