Aggressive malignant phyllodes tumor

Abstract

Introduction: Originally described in 1838 by Muller, phyllodes tumor is a rare fibroepithelial neoplasm which represents roughly 0.3-0.9% of all breast cancers. Phyllodes tumor are divided into benign, borderline and malignant histologic categories. Malignant phyllodes tumor represent anywhere from 10-30% of all phyllodes tumors. This group has both the potential to recur locally and metastasize, however not all malignant phyllodes behave this way. The challenge lays in predicting which tumor will recur locally or metastasize. Distinguishing this subset of malignant phyllodes tumor is paramount.

Presentation of case: We present a case of malignant phyllodes which presented with metastatic disease. What is fascinating about this case is not only the initial presentation but also the aggressiveness of this variation of phyllodes tumor. The patient initially presented with a large mass which encompassed her whole right breast. On surgical pathology the mass measured roughly 31cm in diameter and weighed over 10kg. Within 5 weeks from surgery the patient had suffered brain metastases and also 6 local recurrent tumors. The patient passed roughly 11 weeks after her first visit to our office.

Conclusion: Despite biopsy proven malignant phyllodes tumor, it was near impossible to predict such a rapid course of disease progression in our patient. Our case illustrates the unpredictable nature of this disease in general and it possibly sheds light on a variant of the disease which had undergone an aggressive transformation.

Keywords: Breast; Malignant; Phyllodes tumor.

Fig. 1

Right mastectomy specimen.

Fig. 2

The tumor shows minimal typical ductal features of phyllodes tumor (see photomicrograph, top panel), a minority of the remainder low-grade malignant (see other photomicrograph, left half) and majority high-grade malignant ‘overgrown stroma’. Mature squamous ‘pearls’ (see photomicrograph, lower panel) and chondroid areas (see photomicrograph, middle panel) are obvious divergent differentiation. Foci of geographic necrosis, and broad zones of undifferentiated sarcoma with marked atypia (see other photomicrograph, right half), tumor giant cells, and numerous mitoses and karyorrhectic cells, constitute the most malignant-appearing areas.

Fig. 3

The upper panel shows the most typical phyllodes sampled (10×), the middle panel chondroid differentiation (40×), and the lower panel squamous ‘pearls’ (10×).