Vanishing clear cell carcinoma of the kidney presenting with skin metastases - a case report.

Renal cell carcinoma (RCC) is one of the common genitourinary malignancies that has an increasing incidence. RCC presents a diagnostic challenge due to its wide range of clinical manifestations, often leading to delays in diagnosis and complicating management strategies. These tumours have clear cells in 70% of cases and have a high preponderance of haematogenous metastases to distant organs such as lungs, bones and liver. Skin metastases of RCC in the absence of an obvious renal tumour are rare. We report a young woman with clear cell renal carcinoma with skin metastasis who presented with left loin pain and acute kidney injury, prompting a series of comprehensive investigations, including imaging studies and laboratory tests. Despite these efforts, a primary tumour remained elusive. However, a breakthrough occurred when histopathological examination of a skin nodule biopsy, alongside cytological analysis of nephrostomy fluid, ultimately identified the underlying cause as malignant RCC. Despite commencing palliative Sunitinib therapy based on intermediate risk criteria, the patient died from lung metastases after 6 months of systemic medication. Here is a more succinct version. This case report emphasises the need to investigate renal primaries in unknown-origin metastases and the importance of a thorough diagnostic approach for RCC.