# Co-existence of malignant phylloid tumor and metaplastic malignant spindle cell carcinoma: case report

## TL;DR

A rare case of two aggressive breast cancers co-existing in the same tissue is reported, highlighting diagnostic challenges.

## Contribution

The paper presents an extremely rare co-existence of malignant phyllodes tumor and metaplastic spindle cell carcinoma in a single case.

## Key findings

- A 46-year-old woman was found to have both malignant phyllodes tumor and MMSCC in the same breast tissue.
- The case emphasizes the difficulty in diagnosing and managing rare breast malignancies.
- Post-operative pathology revealed a diagnosis different from the initial core biopsy findings.

## Abstract

Phyllodes tumors (PTs) and Metaplastic Malignant Spindle Cell Carcinoma (MMSCC) are rare and challenging breast malignancies. MMSCC is even rarer and highly aggressive. Surgical excision is the mainstay of treatment for both, but MMSCC generally carries a poorer prognosis. A 46-year-old woman with a history of breast augmentation 4 years ago presented with a rapidly progressing right breast mass. Imaging and core biopsy suggested a malignant PT. A right mastectomy with latissimus dorsi flap reconstruction was done. Initially diagnosed as a malignant PT, the post-operative pathology revealed a co-existence of malignant PT and MMSCC, an extremely rare finding. This case reports the unique challenge of a patient harboring both malignant PT and MMSCC within the same breast tissue. This exceedingly rare co-existence emphasizes the diagnostic complexities associated with uncommon breast malignancies. Our case highlights the challenges of diagnosing and managing uncommon and aggressive breast malignancies.