Author of

• 11842

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  P2.15 - Poster Session 2 - Thymoma (ID 191)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Thymoma & Other Thoracic Malignancies
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11849

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    P2.15-007 - Digital Microscopy Reproducibility Study of Thymic Epithelial Neoplasms (ID 2883)

    09:30 - 09:30  |  Author(s): M.B. Beasley
    • Abstract

    Background
    Thymic epithelial tumors are rare and morphologically heterogeneous which constitutes interpretive challenges to practicing pathologists. Advances in digital imaging provide an opportunity to disseminate knowledge of these rare tumors, and can be potentially useful as diagnostic and educational tools. However the diagnostic reproducibility utilizing digital slide imaging needs to be validated.

    Methods
    Twenty cases of thymomas or thymic carcinomas with characteristic morphologic features were scanned into the APERIO system. The images were sent to pathologists with expertise in thoracic pathology in 6 different centers. The pathologists were asked to classify the tumors according to the World Health Organization (WHO) 2004 classification and to evaluate invasion on the scanned material. In addition, they were asked to indicate their confidence in the diagnosis using the imaging system. Interobserver agreement was evaluated. After discussions of the first 20 cases, a second round representing 10 cases were evaluated by digital images by the participating pathologists.

    Results
    In the initial phase, there was agreement among pathologists for the diagnosis of thymoma and thymic carcinoma in 75 % of cases (n= 14), in the remaining 6 cases, the disagreement was between cases of B3 thymoma and thymic carcinoma in five and between Type A thymoma and thymic carcinoma in one (kappa=0.43, moderate agreement). Perfect agreement was seen in 4 thymoma cases, where all pathologists diagnosed the same WHO type. These were classical cases with pushing borders and large fibrous bands. In other cases there were disagreements among the classification of the tumor as B2, B3, and AB. The cases with most disagreement were histologically heterogeneous with combined patterns. When invasion was evaluated, the overall k coefficient is 0.49 for the presence of invasion. In the second round of cases, we observed an improvement in interobserver agreement for diagnosis thymoma vs thymic carcinoma (kappa = 0.63) and for determination of invasion (present versus absent) (k=0.57). Most pathologists found that the digital images were comparable with glass slides and the overall confidence in the diagnosis was good.

    Conclusion
    The diagnostic accuracy of thymic epithelial tumors by digital images is equivalent to that reported in prior studies using glass slides. Digital imaging is a good tool for remote consultation and educational purposes. In the majority of specimens, pathologists are able to make the correct diagnosis. Major challenges include distinguishing B3 tumors and carcinomas and tumors with morphologic heterogeneity. The overall agreement can be improved after training. This technology could be used to establish a digital slide bank which could provide a method for training pathologists with less experience in the pathology of thymic epithelial tumors, to foster collaborative work in the field, and diagnostic consultation.