RESUMO
<p><b>OBJECTIVE</b>To study the clinicopathologic characteristics of mitotically active cellular fibroma (MACF) of the ovary.</p><p><b>METHODS</b>The clinicopathologic features of 11 cases of MACF from 2008 to 2012 years were retrospectively reviewed and immunohistochemic EnVision method was performed.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>