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Case Reports

Abstract

A 28-year-old female presented to the dermatologist with a nodule of the right chest. A 3.5 cm
excision was performed, and histopathology revealed a leaf-like epithelial pattern formed by
multiloculated spaces lined by benign glandular epithelium within a fibrous stroma. This stroma
was fibrotic with low cellularity and without atypia. Immunohistochemistry revealed glandular
positivity to CK7, and negativity for CK20. P63 staining highlighted myoepithelial cells lining
ducts, and Ki-67 demonstrated a low proliferative index in the stromal and epithelial
components. These findings were consistent with a benign phyllodes breast tumor. These
neoplasms are rare fibroepithelial proliferations, making up 2.5% of all fibroepithelial breast
neoplasms and less than 1% of all primary breast tumors. All phyllodes tumors are
characterized by a phyllodal (from the Greek Phyllodium, or ‘like a leaf’) projections. They are
further subclassified into benign, malignant, and borderline; fortunately, only about 10-15% of
phyllodes tumors are malignant. Surgical excision is the mainstay of treatment, although
recurrences have been reported in 15% - 40% of cases, the higher range more likely from
malignant lesions. Guidelines from the National Comprehensive Cancer Network recommend
excision with or without radiation therapy for these lesions, and clinical follow up to monitor for
recurrences.
Phyllodes tumors are more commonly encountered in non-dermatologic settings, and often are
diagnosed with core needle biopsy. This case demonstrates a unique presentation of a rare
entity rarely encountered by dermatopathologists.