Original Research
AB002. Histopathological heterogeneity in resected thymomas
Florit Marcuse1, Monique Hochstenbag1, Myrurgia Abdul Hamid2, Axel Zur Hausen2, Stephanie Peeters3, Jamie Romeo4, Jos Maessen4, Pilar Martinez5, Marc De Baets5
1Department of Pulmonology, Maastricht University Medical Comprehensive Cancer Center, Maastricht, the Netherlands;
2Department of Pathology, Maastricht University Medical Center+, Maastricht, the Netherlands;
3Department of Radiation Oncology (Maastro Clinic), Maastricht University Medical Center+, Maastricht, the Netherlands;
4Department of Cardiothoracic Surgery, Maastricht University Medical Center+, Maastricht, the Netherlands;
5School for Mental Health and Neuroscience, Maastricht University+, Maastricht, the Netherlands
Correspondence to: Florit Marcuse, MD, PhD. Department of Pulmonology, Maastricht University Medical Comprehensive Cancer Center, Debyelaan 25, 6229 HX, Maastricht, Limburg, Maastricht, the Netherlands. Email: florit.marcuse@mumc.nl.
Background: Morphologic heterogeneity in thymomas depends on histopathological patterns and sampling techniques. There is a lack of knowledge about the incidence and potential impact of heterogeneous thymomas on the disease burden. The primary aim of this study is to investigate the incidence and patient characteristics of thymomas with heterogeneous histopathology.
Methods: All patients who underwent a thymomectomy between 2012 and 2024 in the Maastricht University Medical Center (MUMC) were included and retrospectively analyzed. Thymomas were histologically classified by the 5th edition of the World Health Organization of thymic epithelial tumors. The Masaoka-Koga staging system and 9th TNM classification reported tumor invasion. All thymomas were postoperatively evaluated by the same senior pathologist. After fixation, regular sampling of the specimen is performed, with at least one block per cm of tumor and generous sampling of close margins. The definition of heterogeneous thymoma is based on histologically proven heterogeneity in resected thymoma. Components of mixed histopathology were noted in percentages. Patients with a biopsy were excluded from this study. Pearson’s Chi-squared test was considered statistically significant in case P<0.05.
Results: Morphological heterogeneity was observed in 81 of the 206 included patients (39.3%). The majority of the heterogeneous thymomas were type A–B2 (43.2%) and type B2–B3 (30.9%). Heterogenic thymomas were more frequently observed in non-steroid using patients (34.2% vs. 1.8%, P<0.001). The B3-component was ≥50% in 100% of A–B3 thymomas. The B2 component was ≥50% in 68.6% of A-B2 thymomas. Adjuvant postoperative radiotherapy (PORT) was performed less in heterogeneous thymomas compared to homogenous thymomas (12.3% vs. 25.6%, P=0.02), and most diverse in heterogeneous B3-thymomas compared to homogeneous B3-thymomas (29.0% vs. 73.0%, P<0.001). No significant differences in gender, age, tumor size, or presence of myasthenia gravis were found in patients with homogeneous versus heterogeneous thymomas.
Conclusions: Morphological tumor heterogeneity was found in 39.3% of the resected thymomas. Neglecting the involvement of aggressive thymoma subtypes might have an impact on decisions regarding treatment, such as PORT. Future research is necessary to analyze the consequences of thymoma heterogeneity on recurrence and survival rates. Development of guidelines with sampling recommendations may help identify heterogeneous thymomas.
Keywords: Thymoma; heterogeneity; histopathology
Acknowledgments
None.
Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-25-ab002/coif). S.P. received financing support from Hanarth grant. The other authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional ethics committee of Maastricht University (No. METC: 2018-0491) and individual consent for this retrospective analysis was waived.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
doi: 10.21037/med-25-ab002
Cite this abstract as: Marcuse F, Hochstenbag M, Abdul Hamid M, Zur Hausen A, Peeters S, Romeo J, Maessen J, Martinez P, De Baets M. AB002. Histopathological heterogeneity in resected thymomas. Mediastinum 2025;9:AB002.
