Spontaneously ruptured breast metastasis from renal cell carcinoma 20 years post-nephrectomy: a case report and literature review.

BACKGROUND

Breast metastases from extramammary malignancies are rare, and those originating from renal cell carcinoma (RCC) are exceptionally uncommon. These lesions often follow an indolent course, delaying recognition until acute, life-threatening complications such as hemorrhagic rupture occur. The lack of standardized management guidelines further impedes timely intervention.

CASE PRESENTATION: An 88-year-old woman with a history of radical nephrectomy for clear cell RCC 20 years prior presented with active hemorrhage from a spontaneously ruptured right breast mass. Two years earlier, a 2.5 × 1.5 cm nodule (BI-RADS 3) had been detected but managed conservatively without biopsy, gradually enlarging over the following two years. On admission, physical examination revealed a large, tender mass (∼6.5 × 6 × 7.5 cm) with skin erythema, ulceration, and active bleeding. CT demonstrated the breast mass and revealed two additional imaging-suspected lesions: a right pulmonary nodule and a right adrenal mass. After hemodynamic stabilization, right simple mastectomy was performed, achieving definitive hemostasis. Histopathology and immunohistochemistry (CAIX+, PAX-8+, vimentin+; GATA-3-, GCDFP-15-, ER-, PR-) confirmed metastatic clear cell RCC. The patient declined systemic therapy. At 30-month telephone follow-up, she reported no symptomatic local recurrence or new symptoms; however, no postoperative imaging was performed to confirm this.

CONCLUSION

This case illustrates a critical two-stage progression of breast metastasis from RCC-indolent growth followed by rapid enlargement and hemorrhagic rupture. It underscores that while a BI-RADS 3 lesion in an RCC survivor may be managed with standard short-interval imaging, any interval enlargement or morphological change should prompt a lower threshold for tissue confirmation. An IHC panel (PAX-8/CAIX positivity with negative breast-specific markers) is essential for confirming metastatic RCC. The absence of postoperative imaging in this case-with follow-up limited to symptom-based telephone assessment-highlights the critical importance of radiological surveillance to objectively evaluate disease status.