Malignant Phyllodes Tumor: Imaging Features With Histopathologic Correlation

Abstract

Phyllodes tumors (PT) are rare fibroepithelial lesions of the breast that commonly present as rapidly enlarging, palpable masses. Phyllodes tumors may be classified as benign, borderline, or malignant on the basis of histopathologic analysis. Although malignant PT cannot be distinguished from benign PT on the basis of imaging findings alone, studies suggest that malignant PT tend to be larger and irregular in shape, and they are less likely to have circumscribed margins. If biopsy results are indeterminate, excisional biopsy should be performed. Malignant PT can be difficult to distinguish histologically from sarcomas and spindle cell metaplastic breast carcinoma; the distinction is important for prognosis and treatment. Malignant PT are treated surgically with wide local excision, without a clear role for adjuvant radiation or chemotherapy in most cases. Nearly one-third of malignant PT recur locally, usually within a few years after initial diagnosis. Distant metastatic disease is rare, and the five-year overall survival rate of malignant PT is close to 80%. The purpose of this article is to review the clinical presentation, imaging appearance, histopathology, and management of malignant PT.

High grade phyllodes tumor with osteosarcomatous differentiation: Case report and review of the literature

“…As the imaging profile of PT overlaps with fibroadenomas, an understanding of the characteristics of PT is essential for a definitive diagnosis. The mammographic appearance of all PT is a circumscribed round or oval mass [14] . Calcifications are typically not present; however, when calcifications are present coarse and amorphous findings suggest a benign process, while fine, linear, and branched calcifications typically suggest a malignant lesion [14] .…”

Metastatic and Malignant Phyllodes Tumors of the Breast: An Update for Current Management

“…However, despite excisional biopsy, it remains challenging to histologically distinguish phyllodes from sarcomas and spindle cell metaplastic breast carcinoma, which have different courses of treatment. 15 Diagnosing phyllodes is essential due to malignant stromal transformation, which means a more considerable margin of tissue should be removed during surgery than for non-phyllodes pathology. Advanced imaging studies are recommended to be performed along with tissue diagnosis as research has found the sensitivity of a needle core biopsy’s phyllodes diagnosis to increase from 63% to 76% when combined with radiologic studies.…”

“…19 Phyllodes also tend to show less calcification than fibroadenomas. 15 However, there is still significant overlap between benign and borderline or malignant features of phyllodes in sonographic studies. 20 Some studies suggest no significant association between ultrasonographic characteristics and the grade of phyllodes tumor.…”

“…23 Features such as older age, recurrence, strong lobulation, larger size [benign (3.5 cm), borderline (6.6 cm), and malignant (8.2 cm)], high signal intensity on T2-weighted MRI images, and internal cysts are associated with phyllodes more than fibroadenomas. 15,18,19,24 Studies investigating the association between MRI and histological grading have suggested that tumors with higher signal intensity and an irregular cyst wall on MRI T1-weighted images are histopathologically associated with more hemorrhagic infarction and necrosis. In comparison, tumors with lower signal intensity and a lower apparent diffusion coefficient on MRI T1-weighted images are histopathologically associated with stromal hypercellularity.…”

“…16,17 Sufficient resection of the tumors leads to fewer subsequent surgeries. 18 Ultrasonographic features of size (malignant PT > 7 cm), irregular shape and cystic echogenicity, clefts, a higher Bi-RADS score, and mass vascularization are used to differentiate between malignant and benign phyllodes, 15,18,19 especially in older patients. 20 Elastography on ultrasound may differentiate fibroadenomas from phyllodes based on lesion stiffness, with fibroadenomas demonstrating lower and malignant stiffness values.…”