Evaluation of the Clinicopathological Features Associated With Malignancy of Phyllodes Tumor of the Breast.

Objective: Phyllodes tumor (PT) is a variant of fibroepithelial proliferations of the breast, histologically demonstrating a leaf-like pattern. The WHO has categorized PTs as benign, borderline, or malignant based on their histological characteristics. The objective of this paper is to assess the clinicopathological factors with malignancy in PT of the breast.

Method: Medical records of 101 diagnosed PT patients in the Second Affiliated Hospital of Dalian Medical University between 2008 and 2023 were reviewed. Information on clinical presentation and histopathological findings of the lesions were retrieved from patient files and/or histological reports, respectively.

Results: Of the 101 patients, all were female and had a mean age of 44.35 ± 14.14 years and mean tumor size of 8.3 ± 5.8 cm The distribution for the histological type was benign (n = 54, 53.4%), borderline (n = 36, 35.6%) and malignant (n = 11, 10.8%). Most benign PTs were observed in younger patients, while borderline and malignant PTs involved elderly patients, with a mean age of 47.56 ± 11.86 years for borderline PT and a mean age of 46.55 ± 11.62 years for malignant PT. Benign PTs had a mean size of 5.58 ± 2.29 cm, while those of borderline and malignant were larger, with a mean size of 10.58 ± 6.79 cm and 14.90 ± 6.44 cm, respectively. Malignant PTs had higher lactate dehydrogenase (LDH) levels of 232 ± 91.5 U/L compared to borderline PTs, 177.9 ± 19.9 U/L, and benign PTs, 177.6 ± 39.9U/L. The course of the disease of the malignant PT group was slightly longer (436.9 ± 391.3 weeks) than that of the benign (44.17 ± 71.54 weeks) and borderline (54.33 ± 94.33 weeks). In histopathology, necrosis was observed only in malignant PTs (81.8%), and severe stromal atypia was seen in 72.7% of malignant cases. The mitotic count was highest in malignant PTs at 13.18 ± 4.43 HPF as compared to benign 3.52 ± 2.97 HPF and borderline PTs at 7.28 ± 2.21 HPF.

Conclusion: Benign PTs were more common in this study than malignant or borderline PTs. There was a highly significant correlation between patient age, tumor size, LDH, and disease progression in all subtypes of PT. This analysis showed that malignant PTs were larger and observed in older patients with higher LDH and with a longer duration of the disease. Other factors, in addition to histological properties, are useful in determining PT behavior and management. More studies at an advanced level of evidence in the form of randomized trials are required when developing a risk classification for PT based on patient age, tumor size, and LDH.