Growing
teratoma syndrome (GTS) is a rare condition among
germ cell tumor (GCT) patients during treatment with systemic
chemotherapy. It is characterized by the development of enlarging masses, the normalization of
tumor markers, and the presence of only mature
teratoma in the pathological specimen. The authors present the unusual case of a 15-year-old girl with an
immature teratoma treated with conventional surgery and systemic
chemotherapy. On her follow up, although
tumor markers returned to normal, there was an enlargement of abdomino-pelvic masses confirmed by a PET/TC study. With the diagnosis of a GTS, the patient underwent a com- plete cytoreduction. Histologically, all the specimens contained mature
teratoma tissue. The patient remains clear with no signs of recurrence with no further treatment. The knowledge and awareness of this syndrome are highlighted in order to prevent further unnecessary
chemotherapy and allow an optimal cytoreduction, which seems to be the most effective
therapy so far.