# Muscular Localization of a Clear-Cell Renal Carcinoma: An Atypical Clinical Presentation

## TL;DR

A rare case of clear-cell renal carcinoma spreading to the muscles is reported, highlighting the diagnostic challenges.

## Contribution

This case report adds to the limited literature on secondary muscular metastases of clear-cell renal carcinoma.

## Key findings

- A 67-year-old patient presented with a renal process and metastases to the lungs and arm muscle.
- Histological confirmation revealed secondary muscular involvement of the renal carcinoma.
- Muscle metastases from CCRC are rare and pose significant diagnostic difficulties.

## Abstract

Secondary muscular metastases of clear-cell renal carcinoma (CCRC) are very rare and exceptional. We report the case of a 67-year-old patient who presented clinically with back pain, a chronic cough, and a mass on the left arm. A thoraco-abdomino-pelvic CT scan showed the presence of a malignant renal process associated with multiple pulmonary lesions suggestive of metastases. The lung biopsy returned in favor of CCRC. Histological examination of the right arm mass confirmed the secondary muscular involvement of the renal process. The rarity of muscle metastases from CCRC represents a true diagnostic challenge, warranting systematic investigation.