Supplementary Material for: Cutaneous Metastasis from Renal Cell Carcinoma (RCC): A Case Report

Introduction: Cutaneous metastases from RCC is an uncommon and poorly understood clinical phenomenon that frequently predicts a poor prognosis. Case presentation: A 69-year-old male with a history of type 2 diabetes and benign prostatic hyperplasia (BPH) was diagnosed with stage 4 renal cell carcinoma (RCC) and various cutaneous lesions. A dermatological checkup during his hospitalization revealed asymptomatic subcutaneous nodules and purpuric areas. Biopsy and immunohistochemistry (IHC) staining confirmed the presence of cutaneous metastatic carcinoma, which is consistent with renal cell origin. The immunohistochemistry profile was positive for pancytokeratin, CD10, and vimentin but negative for PAX8, indicating a distinct appearance in RCC patients. Conclusions: This case emphasizes the necessity of recognizing cutaneous metastases as an uncommon presentation of advanced RCC, as well as PAX8's potential role as a diagnostic marker.