Co-existence of ductal carcinoma within phyllodes tumor- A Review of 557 phyllodes tumors from a 20-year region-wide database in Hong Kong and Shenzhen, China

Abstract

Background: Phyllodes tumor (PT) is an uncommon breast tumor arising from the stromal component of the breast, co-existence of ductal carcinoma in-situ (DCIS) or invasive ductal carcinoma (IDC) is even a rare occurrence. To the best of our knowledge, there were only seventeen reported cases of ductal carcinoma arising from PT in the literature. Methods: Retrospective review on two prospectively-maintained databases was performed. We identified 557 patients who were treated for PT in five government hospitals in Hong Kong and in Shenzhen, China from January 1997 to February 2016, pathology slides were retrieved for review by two pathologists. Fisher-exact and Chi-square tests were performed to evaluate the statistical correlation. Result: Three hundred sixty three (65.2%) patients had benign PT, 130 (23.3%) had borderline PT and 64 (11.5%) had malignant PT. Six (1.1%) patients were identified for having co-existing ductal carcinoma within the PT. Four patients were from Hong Kong and 2 were from Shenzhen. Median age was 48 year-old (range 25-54). Ductal carcinoma occurs more frequently in malignant PT than in benign or borderline PT (4.7% vs. 0.6%) (p=0.02). However, malignant PT is not associated with advanced DCIS grade (p=0.1). All patients underwent surgery with clear resection margin. After median follow-up interval of 70 months (Range 2 months 101 months), none of these six patients developed disease recurrence. Conclusions: This study revealed six additional cases to the current knowledge of ductal carcinoma arising from PT. Malignant PT is associated with the presence of co-existing ductal carcinoma.