Rare ovarian tumors often overlooked: 20-year study sheds light on diagnosis and management

A comprehensive 20-year study conducted by researchers at Obstetrics and Gynecology Hospital of Fudan University provides new insights into primary ovarian leiomyomas, a rare type of benign tumor that develops in the ovary. Published in Reproductive and Developmental Medicine, the study analyzed 39 cases treated between 2003 and 2023, offering a detailed look at the clinical characteristics, diagnostic challenges, treatment strategies, and long-term outcomes of this unusual condition.

Ovarian leiomyomas are extremely rare, accounting for only 0.5%–1% of all benign ovarian tumors. Unlike their more common uterine counterparts, they often present atypically, making diagnosis difficult.

“These tumors are frequently asymptomatic and can be easily mistaken for other ovarian conditions, including fibromas or even malignant tumors,” said Dr. Wei Zhang, leading author of the study. “Greater awareness among clinicians is essential to avoid misdiagnosis and unnecessary interventions.”

Among the 39 patients in the study, the majority were postmenopausal women, with an average age of 52.3 years. Most tumors were unilateral and discovered incidentally during routine examinations, while a smaller proportion presented with symptoms such as abdominal pain, distension, or irregular uterine bleeding. The study also found that 27 patients had coexisting uterine fibroids, and some had other gynecological conditions like endometriosis or peritoneal leiomyomatosis.

The research highlights the limitations of imaging in diagnosing ovarian leiomyomas. Ultrasound, the most commonly used diagnostic tool, can detect solid or hypoechoic masses but often lacks specificity. Only three patients in the cohort underwent MRI, which provides more detailed information but still cannot reliably differentiate benign from malignant tumors.

Definitive diagnosis relied on histopathology and immunohistochemistry. Tumors displayed well-differentiated smooth muscle cells arranged in whorled or woven patterns. Immunohistochemical testing confirmed the smooth muscle origin through markers such as Desmin and Inhibin. “Histopathological examination remains the gold standard for diagnosing ovarian leiomyomas,” said Dr. Zhang. “It allows us to distinguish them from other ovarian tumors and ensures appropriate treatment planning.”

All 39 patients underwent surgical excision of the tumors. Notably, none showed signs of sarcomatous transformation, and no recurrences were observed during follow-up periods ranging from 1 to 20 years, with a median follow-up of 12 years. The study emphasizes that surgery, including ovary-sparing procedures in younger women, is highly effective and should be considered the standard of care once malignancy is ruled out.

The rarity and asymptomatic nature of ovarian leiomyomas often result in delayed diagnosis or misdiagnosis. The study underscores the importance of considering ovarian leiomyomas in patients presenting with solid ovarian masses, particularly when concurrent uterine leiomyomas are present. Increasing clinical awareness, applying precise diagnostic methods, and considering ovary-sparing surgery for younger patients can significantly improve patient outcomes.