Cystic-Like HER2-Positive Breast Cancer with Low Tumor-Infiltrating Lymphocytes and High Programmed Death-Ligand 1 Expression in a Young Woman: A Case Report.

ABSTRACT:

Background

HER2-positive breast cancer is generally correlated with poor prognosis, whereas it demonstrates a favorable response to HER2-targeted therapies. Typically, HER2-positive tumors present as solid masses, while cystic features are exceedingly rare.

Case presentation

We present a case of a 37-year-old female with imaging findings of a large cystic mass (9.9 × 1.8 cm) in the left breast. Pathological examination confirmed grade III invasive carcinoma of no special type with HER2 positivity and HR positivity, low tumor-infiltrating lymphocytes (TILs, 5%), and high PD-L1 expression (CPS = 25%). The patient underwent a modified radical mastectomy with axillary lymph node dissection, revealing metastasis in 7 of 15 lymph nodes and the presence of lymphovascular invasion.

SUBMITTER: Lu M 

PROVIDER: S-EPMC12503470 | biostudies-literature | 2025 Jan-Dec

REPOSITORIES: biostudies-literature