Triple-negative breast ductal carcinoma with synchronous brain, lung, and bone metastases. A case report and literature review

Triple-negative breast cancer (TNBC) is an aggressive immunophenotypic category lacking estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression, with a particular propensity for early visceral and central nervous system dissemination. 
We report a 52-year-old woman with an untreated left breast mass, progressive headache and visual disturbance, back pain, and exertional dyspnea. Staging demonstrated a 4.8-cm left breast lesion with axillary adenopathy, three brain metastases, bilateral pulmonary nodules, and multifocal osseous metastases. Core biopsies of the breast and lung showed concordant grade 3 invasive breast carcinoma of no special type with extensive high-grade ductal carcinoma in situ. The tumor was ER-negative, PR-negative, and HER2-negative (IHC score 0, non-amplified), GATA3-positive, and TTF-1/Napsin A-negative. The tumor cells showed high proliferation (Ki-67, 78%); focal cytokeratin 5/6 and EGFR expression, together with TP53 and PIK3CA mutations, supported a biologically aggressive TNBC. 
Symptomatic cerebral lesions were treated with stereotactic radiosurgery, painful vertebral disease with palliative radiation, and systemic chemoimmunotherapy plus bone-modifying therapy produced an initial response. However, new brain metastases, progressive skeletal disease with pathologic L2 fracture, and leptomeningeal dissemination developed rapidly. She died seven months after diagnosis. 
This case highlights the need for urgent neurologic assessment, tissue-confirmed staging, assay-specific biomarker interpretation, and early multidisciplinary and supportive care in de novo metastatic TNBC with CNS involvement.