Intraplacental Smooth Muscle Tumor: A Case ReportErnst, Linda M. M.D.; Hui, Pei M.D.; Parkash, Vinita M.D.International Journal of Gynecological Pathology: July 2001 - Volume 20 - Issue 3 - p 284-288 Case Reports Buy Abstract Author InformationAuthors We present the second reported case of a smooth muscle neoplasm involving the placental parenchyma. On gross examination, the tumor easily separated from the uterus and had a whorled cut surface with finger-like extensions into the villous parenchyma, very similar to the previously described case. The differential diagnosis included a primary smooth muscle tumor of the placenta (placental leiomyoma), a primary uterine neoplasm incorporated into the placenta, and a metastatic sarcoma. In this case, the infant was male, and the polymerase chain reaction technique demonstrated the presence of Y chromosome gene in the placental parenchyma and its absence in the placental neoplasm. Thus, this neoplasm, despite its gross appearance of a primary placental tumor, actually represented an incorporated benign uterine leiomyoma. Department of Anatomic Pathology, Yale University School of Medicine, New Haven, Connecticut. Address correspondence and reprint requests to Vinita Parkash, M.D., Department of Pathology, Room 2–608 East Pavilion, Yale New Haven Hospital, 20 York Street, New Haven, CT 06510. © 2001 Lippincott Williams & Wilkins, Inc.