A 41-year-old man was diagnosed with a cutaneous leiomyosarcoma on the left shoulder. Family history revealed that his brother had died of a metastatic kidney tumor at young age. Although apparently rare, the familial occurrence of cutaneous leiomyosarcoma with renal cancer has been described in the context of hereditary cutaneous leiomyomatosis and renal cell cancer (HLRCC). This rare genetic syndrome is caused by heterozygous mutations in the fumarate hydratase (FH) gene. Hence, the manifestation of these two rare malignancies within one family was strongly suggestive of a common underlying genetic defect. However, mutation analysis in the FH gene excluded HLRCC in this family. Although the familial occurrence of these rare tumors might be coincidental, it cannot be ruled out that, beside FH, mutations in another as yet unknown gene could give rise to both leiomyosarcoma and kidney cancer.