Phyllodes Tumor: A Rare Cause of False-Positive Pregnancy Test Result.

Phyllodes tumors (PT) are rare fibroepithelial neoplasms of the breast that are predominantly benign, but can exhibit malignant characteristics. Elevated beta-human chorionic gonadotropin (beta-hCG) levels, primarily associated with pregnancy and trophoblastic tumors, have been rarely reported in breast cancers and PT. We present a 28-year-old premenopausal female with a rapidly growing, painful mass in the right breast. Imaging and biopsy confirmed a malignant PT. Surprisingly, preoperative testing revealed a positive urine pregnancy test (UPT) and an elevated beta-hCG level (1,152.7 mlU/mL). After pregnancy was deemed unlikely, the patient proceeded with a right total mastectomy. Postoperatively, the beta-hCG level decreased, confirming tumor-related phenomenon. Pathology revealed malignant PT with liposarcomatous components and ductal carcinoma in situ (DCIS). The association between PT and elevated beta-hCG levels is exceptionally rare and poorly understood. This case highlights the importance of considering unusual presentations in PT patients.