# Extensive Invasion of the Pelvicalyceal System Shortly After Combined Locoregional Treatment of Renal Cell Carcinoma: A Report of an Unusual Complication

## TL;DR

A 72-year-old woman with kidney cancer experienced an unusual complication where the cancer spread into the pelvicalyceal system after a combination of embolization and ablation treatments.

## Contribution

This case report highlights an extremely rare and severe complication of RCC treatment involving pelvicalyceal invasion following ablation.

## Key findings

- The patient's RCC spread to the pelvicalyceal system after microwave ablation, despite initial tumor necrosis.
- The complication is believed to result from cell implantation during antenna placement, not from embolization.
- This case underscores the need for caution regarding unexpected tumor progression following locoregional treatments.

## Abstract

Renal cell carcinoma (RCC) is a relatively common malignancy and is often diagnosed incidentally in imaging in early stages, where interventional radiologic techniques provide competent treatment options with minimal risk for major complications. A 72-year-old woman diagnosed with a 5 cm tumor of her right kidney in computed tomography (CT) with typical findings of RCC opted for percutaneous interventional treatment instead of surgical treatment. Transarterial embolization (TAE), followed by ultrasonographically guided microwave ablation (MWA), was performed with no immediate post-interventional complications. The patient returned 10 weeks post MWA with right flank pain and hematuria, and CT revealed almost complete necrosis at the original tumor site but also significant tumor extension in the upper calyces and pelvis of the right kidney. This was histologically confirmed after nephroureterectomy. The complication is thought to be unrelated to the TAE, and cell implantation potentially occurred due to calyceal penetration during antenna placements. TAE and thermal ablation are established techniques for managing locoregional disease. Urinary tract invasion by treatment-naive RCC has been reported in the literature; however, invasion of the pelvicalyceal system by RCC as a result of ablation should be considered an extremely unusual, unexpected, and severe complication, which impairs the prognosis.