Malignant phylloides tumor in pregnancy.

Malignant phylloides tumors are exceedingly rare with few cases being reported in pregnancy. We describe the first case ever reported of a malignant phylloides tumor presenting in the first trimester of pregnancy and provide insight into the complexities of management as well as a review of the known literature. An extensive PubMed literature search for "cystosarcoma," "phylloides," and "pregnancy" was performed. References of each citation were reviewed. Only six previous cases of phylloides tumor in pregnancy were found, none of which were in the first trimester. Medical records of a patient presenting to our institution at 9 weeks gestation with a malignant phylloides tumor were reviewed. We further provide a review of the current literature of the management of phylloides tumor in pregnancy. A 27-year-old white G2P0SA1 woman with no family history of breast cancer presented with a right breast mass at her first prenatal examination at 9 weeks of pregnancy. Ultrasound confirmed a solid mass measuring 24 mm. Core needle biopsy demonstrated a malignant phylloides tumor. She previously had a fibroadenoma removed from the same breast 7 years previously. The current tumor was excised to clear margins. Histopathological examination revealed a 4-cm fibroepithelial tumor with marked stromal cellularity and a high mitotic count (five to seven mitoses/high-power field), confirming the diagnosis of malignant phylloides tumor. The patient continued her pregnancy without complications. Six other cases of phylloides tumor presenting in pregnancy have been reported in the literature, one of which had bilateral disease. Of these, the average patient age was 32 years (range, 28 to 35 years). The majority of these patients presented in their third trimester (mean, 29 weeks; range, 20 to 36 weeks) and often had large tumors (mean, 15 cm; range, 5 to 21 cm). Four of the seven tumors (57%) required a mastectomy. Previous cases have shown phylloides tumors to present in the third trimester as large masses that require mastectomy. With early detection, malignant phylloides tumors can present in the first trimester of pregnancy at smaller sizes; in these patients, breast-conserving surgery is possible.