[257] Phyllodes Tumors: Histologic Features in Relation to Clinical Follow-Up

Monica R Phillips, Yassi Omidvar, Sophia K Apple. UCLA, Los Angeles, CA

Background: Phyllodes tumors (PTs) are rare fibroepithelial neoplasms of the breast which are subdivided into benign, borderline and malignant based on histologic criteria. Surgical excision with a wide margin (>1cm) is the standard treatment to minimize recurrence, however, the histologic classification of PTs does not reliably predict clinical behavior despite adequate excision. This study aims to examine the clinicopathologic features and outcome of PTs in order to identify risk factors for local recurrence and distant metastasis.
Design: A retrospective review of 62 patients with PTs from 1996-2012 was analyzed with regard to histologic features and clinical follow-up. We included only patient samples with slides available for review and excluded all cases that had no or loss of clinical follow-up. Analysis of histologic features included tumor size, mitotic rate/10 HPF, stromal overgrowth, periglandular cuffing, cellularity, necrosis, heterogeneous differentiation, borders, margin width and co-existing fibroadenoma (FA). Clinical features included age, follow-up duration, type of surgery, local recurrence, distant metastasis and death rate.
Results: Benign, borderline and malignant PTs comprised 31/62 (50%), 14/62 (23%) and 17/62 (27%) with mean age of 38, 44 and 50 years, respectively. Median follow-up was 54 months.

Table 1. Clinicopathologic features & outcome of PT
 Benign PTBorderline PTMalignant PT
Mean Age (yr)384450
Mean size (cm)
Avg mitoses/10 HPF1517
Stromal overgrowth16% focal43% focal88% diffuse
Necrosis (coagulative)0%0%41%
Heterologous diff0%0%41%
Co-existing FA61%64%53%
Irregularly pushing29%43%0%
Local excision vs mastectomy0% vs 100%86% vs 14%47% vs 53%
Recurrence rate13%14%18%
Margin: recurrence rate   
@: 4/9 (44%)1/4 (25%) pushing3/14 (14%)0
<1mm: 3/9 (33%)1/4 (25%) pushing02/3 (67%)
2mm: 1/9 (11%)1/4 (25%) irreg pushing00
neg (>1cm): 3/9 (33%)1/4 (25%) pushing2/10 (20%)0
Distant metastasis0%0%12%
Death rate0%0%12%

Conclusions: PTs are seen within and/or adjacent to FA in 60% of patient samples which supports the hypothesis that FA is a precursor lesion to PT. Recurrence, death rate and distant metastasis are directly related to the histologic findings of stromal overgrowth, necrosis and heterologous differentiation in malignant PTs. The status of the resection margin was not associated with recurrence free survival in benign PTs, while close margin status in borderline and malignant PTs was related to recurrence rate. The type of surgery was not a significant factor for local recurrence.
Category: Breast

Monday, March 4, 2013 1:00 PM

Poster Session II # 44, Monday Afternoon


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