Abstract
Juvenile granulosa cell tumor (JGCT), classified as a sex cord-stromal tumor, is a rare neoplasm. This is an instructive case report of JGCT accompanied by augmented interleukin (IL)-6 secretion. A 13-year-old girl with prolonged fever and delayed puberty was diagnosed with JGCT of the left ovary based on an imaging study and pathological investigation. Although it was not clear whether IL-6 was secreted from the tumor cells, her serum level of IL-6 was very high. After tumorectomy, the patient's symptoms immediately disappeared, her IL-6 level decreased, and she entered puberty. Therefore, augmented IL-6 secretion production induced by tumors should be considered a potential cause of prolonged fever and/or delayed puberty.