Improvement of Suspected Paraneoplastic Large-Vessel Vasculitis after Breast Cancer Resection: A Case Report

Paraneoplastic vasculitis is an uncommon manifestation of malignancy and has been reported mainly in association with lung cancer, renal cell carcinoma, and hematologic malignancies. Breast cancer-associated vasculitis is rare, and presentation as large-vessel vasculitis (LVV) is particularly uncommon. We report a rare case of suspected paraneoplastic LVV occurring concurrently with breast cancer, in which inflammatory activity stabilized after surgical resection of the primary tumor.

A 54-year-old woman presented with pain in the left upper limb and left thigh. CT suggested left breast cancer with ipsilateral axillary lymph node metastasis. PET/CT showed fluorodeoxyglucose uptake in the left breast lesion and left axillary lymph node, as well as in multiple large vessels, including the carotid arteries, subclavian arteries, aorta, iliac arteries, and femoral arteries. Laboratory testing revealed an elevated C-reactive protein level of 10.93 mg/dL, whereas immunoglobulin A and antineutrophil cytoplasmic antibodies were within the normal ranges. There was no evidence of infection, autoimmune disease, or drug-induced vasculitis. Because breast cancer-associated paraneoplastic LVV was suspected, prednisolone was initiated at 30 mg/day, resulting in rapid improvement in symptoms and inflammatory response. The patient subsequently underwent breast-conserving surgery with axillary lymph node dissection while receiving prednisolone at 15 mg/day. Pathological examination revealed invasive ductal carcinoma, pT1c pN1 cM0, stage IIA, luminal A subtype. After surgery, prednisolone was tapered to 5 mg/day without recurrence of vasculitis, and inflammatory activity remained controlled during follow-up.

LVV occurring concurrently with newly diagnosed breast cancer may represent a paraneoplastic manifestation after exclusion of autoimmune, infectious, and drug-induced causes. This case suggests that tumor resection may contribute to stabilization of inflammatory activity by reducing tumor-related antigenic or cytokine-mediated stimulation. Surgical treatment may therefore have a potential role not only in local oncological control but also in the management of paraneoplastic immune dysregulation in selected patients with resectable breast cancer.