The 28-year-old, capped once by the Netherlands, is a former Feyenoord and Basel player who joined Hertha in August after a four-year spell with Mainz.
His club said in a statement: "Jean-Paul Boetius has been diagnosed with a testicular tumour following the results of a urological test on Wednesday, and will be out for the foreseeable future. The 28-year-old will undergo an operation on Friday."
Jean-Paul Boëtius had a urological test on Wednesday, where a testicular tumour was discovered. We will inform you further once we have more information. Our thoughts are with you, Djanga! 💙#GemeinsamHertha #HaHoHe pic.twitter.com/onOpiRfrw3— Hertha Berlin (@HerthaBSC_EN) September 22, 2022
Fredi Bobic, Hertha's managing director of sport, backed Boetius to make a full recovery.
Bobic said: "As tough as it is to hear at first, we are full of hope that Jean-Paul will be able to recover and return to us as soon as possible.
"He will receive our full support, until he returns. The Hertha family are by his side and wish him all the best."
The news for Boetius follows Borussia Dortmund striker Sebastien Haller being found to have a testicular tumour in July, just weeks after joining from Ajax. Haller had surgery and has since undergone chemotherapy.