Objective  To investigate the clinical and pathological characteristics of ovarian cellular fibromas.

  Methods  The sample consisted of 24 cases of ovarian cellular fibromas from February 2008 to March 2017 in the Obstetrics and Gynecology Hospital of Fudan University. Clinical histories were retrieved, and pathological slides were reviewed.

  Results  The age of the patients ranged from 17 to 70 years old, with a mean age of 46.5 years. Clinical symptoms included ovarian masses, abdominal pain, or pleuroperitoneal fluid. Serum CA125 notably increased in two patients. Of the 24 cases, 13 and 10 occurred in the right and left ovaries, respectively, and one case occurred bilaterally. Tumor cells were densely cellular in all cases and were mitotically active in three cases (5-7/10 high power fields). A minor component of sex cord elements ( < 10% area of the tumor) was present in three cases, and luteinized cells were observed in four cases. None of the cases manifested recurrence during follow-up ranging from 1 month to 109 months.

  Conclusion  Ovarian cellular fibromas are pure ovarian stromal tumors that may manifest mitotic activity, sex cord elements, and luteinization. Some patients present with pleuroperitoneal fluid and increased CA125. Thus, the pathological features of cellular fibromas must be mastered to avoid misdiagnosis for other benign or malignant tumors and improper treatment.