Benign Phyllodes Tumor with Extensive Cystic Squamous Metaplasia, Clinically Presenting as Malignant Phyllodes

Phyllodes tumor are very rare fibroepithelial lesions which comprises 0.3%–1% of all primary breast tumors with peak age around 40–50 years. Phyllodes tumor are classified ino three types: Benign, borderline and malignant tumors. Metaplastic change is very rare in these tumors and can involve both epithelial or stromal components. Stromal metaplastic changes include cartilage, bony or fatty change. Epithelial metaplastic changes include apocrine or squamous change. About 10% of phyllodes tumor show squamous metaplasia. We report a case of 47-year-old patient presenting with large lump in right breast measuring 16 cm × 15 cm × 11 cm, occupying all four quadrants. Clinically, it appeared as malignant phyllodes. But, microscopically, it was benign phyllodes tumor having extensive cystic squamous metaplasia.