# A case report of metastatic renal cell carcinoma and ANCA associated vasculitis

## TL;DR

This case report describes a rare instance where a patient with kidney cancer also developed a rare autoimmune disease, highlighting the complex relationship and treatment challenges between the two conditions.

## Contribution

The novelty lies in presenting a rare concurrent case of metastatic RCC and AAV, emphasizing their potential pathophysiological link and treatment complexities.

## Key findings

- A 53-year-old patient with metastatic RCC developed AAV after starting tyrosine kinase inhibitor therapy.
- Treatment involved discontinuing immunotherapy and using glucocorticoids and rituximab for AAV.
- The case suggests a pro-inflammatory environment from RCC may contribute to AAV development.

## Abstract

Renal Cell Carcinoma (RCC) may uncommonly present concurrently with anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV). Most instances are malignancies discovered incidentally during the work up after a diagnosis of AAV; however, the significant overlap between these disorders potentially suggests a more complex pathophysiology. We present the case of a 53-year-old gentleman who was diagnosed with metastatic RCC who later developed rapidly progressive kidney failure and a vasculitic rash after commencement of a tyrosine kinase inhibitor and was ultimately diagnosed with subsequent concurrent AAV. Treatment included suspending immunotherapy, glucocorticoids, and rituximab induction. This case highlights the unique scenario of concurrent RCC and AAV, including the potential pathophysiology of a pro-inflammatory milieu created in the setting of RCC which permits AAV. It also outlines the complexity of treating an autoimmune disorder in the setting of an active cancer requiring immunotherapy and the difficult balance between these two treatment paradigms.