Benign Biphasic Tumors of the Mullerian Tract - a Mimic of Phyllodes Tumor. A Clinical-Pathologic Description of 21 Cases.

Objective: A review of the clinical-pathologic characteristics and outcomes of biphasic polyps occurring in the female genital tract, not meeting the diagnostic criteria of Mullerian Adenosarcoma (MA).

Methods: An archival database search was run, after IRB approval, between 2001 and 2019, using terminology such as "Mullerian adenofibroma," "atypical Mullerian adenofibroma," "polypoid adenofibroma," and "atypical polyp with increased stromal cellularity." Two pathologists (JW and MRQ) reviewed all the retrieved cases and documented the morphologic features with particular emphasis on the presence of any features of Mullerian adenosarcoma. Follow-up data were also abstracted.

Results: Twenty-one cases, 12 cervical and 9 endometrial lesions, constituted the study cohort. Patients ranged from 26 to 64 years (median 49 years). On review, 20 of 21 of those cases showed Phyllodes-like architectural patterns. However, only one case showed all four features of MA, all of which were focal and inconspicuous. Follow-up (median duration of 5 years) did not document any recurrences in any of the 21 cases after excision.

Conclusion: This series adds to the growing body of literature affirming the existence of benign biphasic Mullerian polyps encountered in the endometrium and cervix that fall short of the Mullerian adenosarcoma diagnosis.