Abstract
Thecoma is a rare type of ovarian sex cord-stromal tumor, accounting for about 0.5% to 1.0% of ovarian tumors. This tumor mainly occurs in women before and after menopause and is relatively rare before puberty. Thecoma generally consists of benign solid or cystic masses and can be accompanied by ascites, abnormal hormone levels, and elevated CA125. Most of these tumors have a good prognosis. In this case study, we report on a 16-year-old girl who presented with bloating and a huge abdominal mass. A full-body computed tomography (CT) showed a huge cystic mass in the pelvic and abdominal cavities indicative of malignancy. The abdominal ultrasound (US) showed a huge solid hypoechoic mass reaching up to the lower abdomen and pelvic cavities. The tumor markers and estradiol were within the normal range. The tumor was surgically removed, and the histopathological examination revealed a solid thecoma measuring about 26 cm × 20 cm × 12 cm. Although thecomas mostly occur in perimenopausal and postmenopausal women, the findings of this case study suggest that thecomas should not be ruled out in adolescents presenting with a large pelvic mass. Abdominal US could be used to facilitate the differentiation between fluid-filled and solid masses, which can be difficult to distinguish on a CT scan.