BACKGROUND
Ventriculoperitoneal shunt placement is a common neurosurgical procedure to treat hydrocephalus, but there are few reports of breast cancer occurring in the shunt’s pathway.
CASE REPORT
The patient was an 86-year-old woman. She visited our hospital because she became aware of a mass in her left breast. She had undergone ventriculoperitoneal (VP) shunt surgery for normal-pressure hydrocephalus. Palpation revealed an irregular mass at 9 o’clock of the left breast. Breast ultrasonography showed a mass with indistinct borders, rough margins, and skin infiltration with a maximum size of 36 mm at 9 o’clock of the left breast. The VP shunt tube was observed in the center of the mass. Core-needle biopsy was performed and the diagnosis was invasive ductal carcinoma and the subtype was triple-negative. Contrast-enhanced computed tomography showed that the ventriculoperitoneal shunt passed from the left ventricle through the center of the left breast mass and into the abdominal cavity. We were concerned about shunt occlusion and infection if the breast cancer was left untreated, so after consultation with the neurosurgeon, we performed the surgery. The ventriculoperitoneal shunt was rerouted from the left thoracoabdomen to the right thoracoabdomen. In addition to left mastectomy, the fistula in the abdominal wall was removed to prevent recurrence in the shunt’s path. Histopathology results showed invasive ductal carcinoma and the subtype was triple-negative. There were no malignant findings in the abdominal wall fistula.
CONCLUSIONS
The cases of distant metastasis of cancer caused by VP shunt have been reported. These events suggest that treatment of breast cancer arising in the VP shunt pathway should include additional procedures to prevent cancer seeding in addition to routine breast cancer surgery. In this case, we performed mastectomy, VP shunt rerouting, and abdominal wall fistulotomy.

Keywords: Breast Neoplasms; Mastectomy; Ventriculoperitoneal Shunt