ER-positive/HER2-positive breast cancer with rare paranasal sinus and skull metastasis

What happened, in summary

This 70-year-old Pakistani woman had type 2 diabetes, hypertension, and no family history of breast cancer. Four years before her emergency presentation, she had undergone left mastectomy with level 2 axillary clearance for invasive ductal carcinoma in the upper outer left breast. The primary tumor measured 3.2 cm, was grade II, and had lymphovascular invasion. Two of 15 lymph nodes were positive, giving a pT2N1 classification. Biomarkers were ER-positive with Allred score 7, PR-negative, HER2-positive by IHC 3+, and Ki-67 25%. Adjuvant therapy was delayed because she lived far from tertiary hospitals and could not afford timely treatment; radiotherapy was given 2 years later, and chemotherapy was started when metastatic progression occurred. She later came to the emergency department with 4 days of altered mental status, decreased oral intake, and aphasia. Examination found an absent gag reflex and reduced sense of smell. Brain CT showed an aggressive destructive lesion involving the left frontal sinus and ethmoid air cells, with a soft-tissue component affecting the posterior parietal bone and extending into the extradural space, but without definite intracranial extension. Biopsy confirmed metastatic invasive ductal breast carcinoma. The metastasis remained ER-positive, PR-negative, and HER2-positive, and GATA3 staining supported breast origin. She chose palliative care and wanted to avoid invasive treatments. She received palliative radiotherapy to the left chest wall and axilla, along with psychosocial and symptom-focused support. The metastasis did not respond to palliative radiotherapy, and her condition declined. She died 2 years after her initial presentation to that facility, despite continued palliative support.