Author of

• 20118

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  OA 03 - Mediastinal and Esophageal Tumor: Insight and New Treatment (ID 654)

  • Event: WCLC 2017
  • Type: Oral
  • Track: Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies
  • Presentations: 1
  • Moderators:M. Chida, Jhingook Kim
  • Coordinates: 10/16/2017, 11:00 - 12:30, Room 311 + 312

  • 22952

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    OA 03.06 - Clinicopathologic, Immunophenotypic and Genetic Studies of Mediastinal Paragangliomas (ID 8339)

    11:55 - 12:05  |  Author(s): B. Kipp
    • Abstract
    • Presentation
    • Slides

    Background:
    Paragangliomas (PGLs) are rare neuroendocrine neoplasms arising from paraganglia of the autonomic nervous system. Only about 2% of all PGLs are found in the mediastinum; therefore they are not thoroughly investigated. Our study aims to characterize the clinicopathologic, immunophenotypic and genetic features of mediastinal PGLs.
    
    Method:
    Surgical files of Mayo Clinic Rochester and an institutional database (1973-2015) were searched for mediastinal PGLs. Thirteen patients were previously reported (Brown ML et al, Ann Thorac Surg 2008). All cases were reviewed by a thoracic pathologist to confirm the diagnosis. Immunohistochemistry was performed using antibodies to SDHB, Ki-67, ATRX, p53, PD-L1 (clone SP263) and ASCL1. Ki-67 labelling index (LI) was calculated as the mean percent Ki-67-positive cells per 3 HPF. Next generation sequencing (NGS) used a 50-gene neuro-oncology panel. Clinical data were retrieved from medical records. Statistical analysis was performed.
    
    Result:
    Twenty-four patients with mediastinal PGLs (7 men, 29.2%) had a median age at time of surgery of 44.6 years (19.8-72.2). Twenty-one (87.5%) paragangliomas were completely resected, 3 had an incomplete resection. The median tumor size was 5.1 cm (1.6-14). The median Ki-67 LI was 4.1% (0.5-29.7). PD-L1 was expressed in 10% (n=2), 1% (n=4) or 0% (n=17) of tumor cells. ASCL1 was focally expressed in 2 of 23 (8.7%) cases. Diffuse loss of SDHB expression was seen in 17 of 22 (77.3%) cases. ATRX was expressed in all 22 cases tested, but its expression was patchy in 1 case that showed ATRX duplication by NGS. NGS, performed in 19 cases, revealed a single pathogenic mutation in 10 cases including SDHB (n=3), SDHD (n=6) and ATRX (n=1); and two or more mutations in 2 cases including SDHC+TERT (n=1) and SDHB+ATRX+TP53 (n=1). Two additional patients were found to have an SDHB mutation. Ten of 21 patients with available SDHx mutation status (47.6%) had no SDHx mutation. Median follow up, available in 21 patients, was 4.7 years (0.8-11.5). Five patients (2 of which with SDHx mutation) developed metastases and/or recurrence; 4 patients (2 without SDHx mutation, 2 with unknown SDHx mutation status) died (1 perisurgically, 3 of unknown cause at 2.3, 5.8, and 10.6 years after surgery each). Statistical analysis of clinicopathologic features based upon SDHx mutation could not be performed due to the small number of cases.
    
    Conclusion:
    Our study demonstrates that the majority of mediastinal PGLs harbors an SDHx gene mutation. Alterations in ATRX gene might represent another genetic event in mediastinal PGLs.
    
    

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