[Mitotically active cellular fibroma of ovary: a clinicopathologic analysis]

To study the clinicopathologic characteristics of mitotically active cellular fibroma (MACF) of the ovary.

The clinicopathologic features of 11 cases of MACF from 2008 to 2012 years were retrospectively reviewed and immunohistochemic EnVision method was performed.

The age of patients ranged from 21 to 65 years (mean = 46 years). The maximum tumor diameter varied from 6 to 16 cm (mean = 9.8 cm). The tumors were densely cellular and composed of intersecting bundles of spindle cells, sometimes associated with storiform pattern. The mitotic count ranged from 4 to 20 per 10 high-power field (mean = 8.4). Atypical mitotic figures were not identified and coagulative tumor necrosis was not found. There was at most mild to moderate degree of nuclear atypia. Immunohistochemically, 8 cases showed positive stain for vimentin and 5 cases expressed diffusely or focally WT-1. In 6 cases, Ki-67 positive index ranged from 5%-30%, including 1 case (10%), and 1 case (30%) in which mitotic figures were 20/10 HPF. CK,AE1/AE3, CD117, CD34, CD99 and desmin were negative in the detected 5 cases. Reticular fiber staining in 2 cases showed dense reticular fibers enveloping individual tumor cells. Ten patients who followed-up range from 4 to 38 months were alive without evidence of recurrence or disease progression. One patient was alive with local recurrence 94 months after surgery.

Cellular fibromatous neoplasm with mitotic count of ≥ 4/10 HPF but relatively bland nuclear features should be considered as MACF rather than ovarian fibrosarcoma. MACF is a group of ovarian tumor which carries a low malignant potential and occasional chance of recurrence.