Mediastinal Mass Following Successful Chemotherapy for Ovary Dysgerminoma: Benign Process or Disease Relapse? A Case Report

Abstract Background Ovarian dysgerminoma is a rare tumor that affects adolescent girls and young women. Due to its high radio-chemosensitivity, prognosis is normally excellent. Relapses occur in less than 20% of early stage disease, but are more frequent in advanced disease. It is known that some benign mediastinal processes may mimic tumor relapse, particularly in young patients. This is the case of physiologic thymic hyperplasia, which occurs as a rebound phenomenon after chemotherapy in young women with ovarian dysgerminoma. Until now, no cases of dysgerminoma with benign mediastinal mass have been published. Case A young woman with bulky ovarian dysgerminoma, who obtained complete disease remission after chemotherapy, subsequently developed a mediastinal mass which was initially confused with a mediastinal relapse. CT scan features (close thymic location, homogeneous hypodensity, absence of infiltration of mediastinal structures) and subsequent PET/CT scan (homogeneous glucose uptake and a typical inverted V morphology) supported the diagnosis of thymic hyperplasia. No further invasive procedures were performed. 34 months from the diagnosis the patient is in good physical condition with no signs of relapse. Conclusions Our case underlines the importance of knowing the age- and treatment-related incidence of physiologic thymic hyperplasia in young women with ovarian dysgerminoma in order to reduce the potential pitfalls and to avoid unnecessary invasive diagnostic procedures.