Benign Phyllodes Tumour With Cystic Squamous Metaplasia: A Rare Histology Finding

Area of Science:

• Oncology
• Pathology
• Breast Cancer Research

Background:

• Phyllodes tumours (PT) are rare fibroepithelial neoplasms of the breast, accounting for 0.3-1% of breast cancers.
• Histological classification of PT into benign, borderline, and malignant types is crucial for patient management.
• Metaplasia within PT is uncommon, with cystic squamous metaplasia being particularly rare.

Observation:

• A case of a 63-year-old female presenting with a palpable left breast lump.
• Histological examination revealed a benign Phyllodes tumour with focal cystic squamous metaplasia, keratin production, and foreign-body reaction.
• Review of prior core biopsy showed features overlapping benign and borderline Phyllodes tumours.

Findings:

• The study highlights a rare case of benign Phyllodes tumour exhibiting cystic squamous metaplasia.
• A subsequent, even rarer finding of a foreign-body reaction to keratin spillage within the tumour was observed.
• The histological presentation was unique, emphasizing the diverse potential appearances of Phyllodes tumours.

Implications:

• This case expands the understanding of rare histological variations in benign Phyllodes tumours.
• Recognizing these rare features is essential for accurate diagnosis and appropriate clinical management of breast neoplasms.
• The findings underscore the importance of thorough histological evaluation in complex breast pathology cases.