OBJECTIVETo study the clinicopathologic features and differential diagnosis of recurrent Müllerian adenofibroma (MAF) of the uterus.

METHODSClinicopathologic information of 7 cases of recurrent MAF of uterus was retrieved from January 1992 to April 2006 and compared with 12 cases of MAF without recurrence and 14 cases of low-grade Müllerian adenosarcoma (MAS). EnVision immunohistochemistry of estrogen receptor (ER), progesterone receptor (PR), smooth muscle actin (SMA), CD10, Ki-67 and p53 were performed in all cases.

RESULTSAll cases of recurrent MAF of the uterus were polypoid, lobulated, and broad based mass arising from the corpus or cervix. Microscopically, the tumor consisted of benign epithelial and mesenchymal components with low mitotic activity ( ≤ 1/10 HPF). The clinical and pathologic features of 3 recurrent tumors were similar to their primary tumors, while 4 cases of recurrent tumor presented with focally higher cellularity and mitotic activity, meeting the diagnostic criteria of adenosarcoma. The stromal expression patterns of ER, PR, SMA and p53 in recurrent MAF were similar to those of clinically benign MAF and low-grade MAS. Negative or focally positive stromal cell expression of CD10 was seen infrequently in recurrent MAF (1/7) and clinically benign MAF (1/12). In contrast, a moderate to strong CD10 staining was frequently seen in MAS (9/14, P < 0.05). The difference of Ki-67-labeling index between MAF and MAS did not reach a statistical significance (P > 0.05). Ki-67-labeling index increased in areas of periglandular stromal cuffing as compared with interglandular areas in all MAS cases, but it was not observed in either recurrent MAF or clinically benign MAF cases.

CONCLUSIONSRecurrent MAF may be associated with aggressive behavior. It is difficult to distinguish MAF from low-grade MAS. CD10 and Ki-67 staining pattern in stromal cells may be helpful for the differential diagnosis.