Thymic Hyperplasia after Chemotherapy: Combined Experience of Two Centers

Background: Lymphoid tissue hyperplasia has been described in oncologic patients after receiving chemotherapy at different sites including: adenoids, tonsils, nasopharynx and thymus. Thymic hyperplasia has been reported more frequently in the pediatric age, associated most commonly with lymphomas. Biopsies of the thymic tissue show benign growth most likely due to a rebound effect after the chemotherapy treatments. Thymic hyperplasia occurring during cancer remission after chemotherapy treatment poses a diagnostic dilemma to clinicians. Our aim is to describe our experience with eight patients (pts) who were treated with chemotherapy and subsequently developed benign thymic hyperplasia.

Methods: Retrospective analysis.

Results: We reviewed the medical records of 8 consecutive pts seen in our two institutions between 2004 and 2015 who were referred with the diagnosis of breast cancer (7 pts) or lymphoma (1 pt). All pts were female; median age was 41 years, with an age range from 35 to 44. Each pt presented with benign thymic hyperplasia following the completion of chemotherapy treatments. The median time for diagnosis of thymic hyperplasia (demonstration of a new anterior mediastinal mass on follow-up CT scan) was 7 months following completion of chemotherapy, with a range of 1 to 11 months. In the first patient, the diagnosis was confirmed after thymic removal by thoracotomy and the remaining pts were followed up with serial computed tomography (CT) scans. All eight pts remain in complete remission from their primary cancers.

Conclusion: Thymic hyperplasia following chemotherapy treatment is an unusual benign phenomenon that merits awareness by clinicians in order to prevent unnecessary invasive and risky procedures.