Invasive Micropapillary Carcinoma of the Breast with an Encapsulated-Like Pattern: An Unreported Entity?

Area of Science:

• Oncology
• Pathology
• Radiology

Background:

• Invasive micropapillary carcinoma (IMPC) is a rare breast cancer subtype.
• IMPC is characterized by specific growth patterns and cell morphology.
• Encapsulated patterns are typically associated with other breast tumor types.

Purpose of the Study:

• To report a novel case of invasive breast carcinoma with both encapsulated and micropapillary features.
• To describe the clinical, imaging, and pathological characteristics of this rare entity.
• To contribute to the understanding of breast cancer heterogeneity.

Main Methods:

• Case presentation of a 71-year-old woman with a left breast mass.
• Magnetic Resonance Imaging (MRI) for mass characterization.
• Core needle biopsy for histopathological diagnosis.
• Neoadjuvant chemotherapy followed by mastectomy and sentinel lymph node biopsy.

Main Results:

• Diagnosis of invasive carcinoma with micropapillary features (ER/PR-positive, HER2-negative).
• Mastectomy revealed an 11 cm encapsulated tumor with tubulo-micropapillary structures.
• No lymphovascular invasion or lymph node metastasis was identified.

Conclusions:

• This case represents the first reported instance of invasive micropapillary carcinoma with an encapsulated pattern.
• The findings expand the spectrum of breast cancer presentations.
• Accurate pathological assessment is crucial for managing rare breast cancer subtypes.