Background. A 24-year-old woman presented with a 45 cm complex cystic renal mass, which was resected. The tumor was a type-2 papillary renal cell carcinoma (pRCC-2), and several nodules remained. The patient was treated with mammalian target of rapamycin complex 1 (mTORC1) inhibitors, but after 5 months the tumor had progressed. Genetic testing of the patient revealed a novel heterozygous germline mutation in the gene encoding fumarate hydratase (FH), an enzyme of the tricarboxylic acid (TCA) cycle. As the tumor exhibited loss of heterozygosity for FH and markedly reduced FH activity, and in the absence of other established therapies, treatment with the glycolytic inhibitor 2DG (2-deoxy-D-glucose) was explored.

Investigations. CT, histology, immunohistochemistry, genetic studies, 2-deoxy-2-(¹⁸F)fluoro-D-glucose (¹⁸FDG)-PET/CT, FH enzymatic assays, reconstitution experiments and in vitro studies of the effects of 2DG on FH-deficient tumor cells.

Diagnosis. pRCC-2 arising in a patient with a novel germline FH mutation and de novo hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome progressing after mTORC1 inhibitor therapy.

Management. Surgical resection of the renal mass, treatment with mTORC1 inhibitors followed by 2DG. Unfortunately, 2DG was not effective, and the patient died several weeks later.