Case Report
AB047. Mixed type A thymoma and micronodular thymoma with lymphoid stroma: a case report of an unusual tumor and literature review
Rahma Ayadi1,2,3, Rahma Yaiche1,2,3, Yasmine Dhouibi1, Emna Braham1,2, Olfa Ismail1,2, Nadia Ben Jamaa1,3, Aida Ayadi1,2,3
1Pathology Department, Abderrahmen Mami Hospital, Ariana, Tunisia;
2Research Laboratory, Ariana, Tunisia;
3Faculty of Medicine of Tunis, El Manar University, Tunis, Tunisia
Correspondence to: Rahma Ayadi, MD. Pathology Department, Abderrahmen Mami Hospital, Rue de l’Hôpital, 2080 Ariana, Tunisia; Research Laboratory, Ariana, Tunisia; Faculty of Medicine of Tunis, El Manar University, Tunis, Tunisia. Email: rahma.ayadi@fmt.utm.tn.
Background: Micronodular thymoma with lymphoid stroma (MNTLS) is a rare subtype of thymoma and accounts for only 1–5% of all thymoma. Though the histogenesis of MNTLS is not yet elucidated, it is postulated that type A thymoma and MNTLS shared a common histogenesis with suspected medullar origin. To date, only five cases of mixed thymoma composed of type A thymoma and Micronodular thymoma has been adequately described in the literature.
Case Description: A 76-year-old woman presented with a mediastinal mass incidentally found on routine chest radiograph during a regular health check-up. There was no evidence of myasthenia gravis. On further evaluation by chest computed tomography, an 8.3 cm mediastinal mass was identified in the left anterior mediastinum. The mass had a lobulated contour, suggested a thymic epithelial tumor. He received extended thymectomy via median sternotomy. On cut sections, the tumor measured 9 cm × 7 cm and was enclosed by a thin fibrous capsule. On histological examination, two different types of thymoma were noted, showing partly infiltrative growth into the fibrous capsule. Large nodules seen were composed of epithelial cells with sparse lymphocytes. Spindled tumor cells arranged in short fascicles. These characteristics, together with positivity for cytokeratin, were compatible with type A thymoma. The type A area showing gradual transition into the rest of the tumor, which harbored a mixture of epithelial and lymphoid components. Epithelial tumor nodules were segregated by lymphoid stroma. Tumor cells were strongly positive for cytokeratin. Lymphoid stroma was positive for CD1a. The patient was diagnosed ultimately with mixed type A thymoma and MNTLS.
Conclusions: In the present case, epithelial components of type A thymoma and MNTLS showed similar histologic and immunohistochemical profiles with areas of gradual transition, suggesting type A thymoma and MNTLS share a common histogenesis.
Keywords: Mixed type A thymoma and micronodular thymoma with lymphoid stroma; thymoma; case report
Acknowledgments
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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-ab047/coif). The 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. All procedures performed in in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.
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-ab047
Cite this abstract as: Ayadi R, Yaiche R, Dhouibi Y, Braham E, Ismail O, Jamaa NB, Ayadi A. AB047. Mixed type A thymoma and micronodular thymoma with lymphoid stroma: a case report of an unusual tumor and literature review. Mediastinum 2025;9:AB047.
