Fig. 1.

Lesions and folliculin (FLCN) mutation in case 1. a Abdominal computed tomography (CT) scan with intravenous contrast reveals a renal mass in the upper pole of the left kidney (arrow). b Abdominal CT scan with intravenous contrast reveals a renal mass in the right kidney (arrow). c CT scan shows left pneumothorax (arrow). d Histopathology of the left renal tumor shows a monotonous cellular pattern with mild nuclear pleomorphism and abundant, partly eosinophilic cytoplasm with a perinuclear halo (chromophobe renal cell carcinoma). e Histopathology of the right renal tumor shows clear cytoplasm surrounded by a distinct cell membrane (clear cell carcinoma). f Both the patient and his son have a deletion of AG (c.946-947delAG) in exon 9 of the FLCN gene, which causes a frameshift mutation starting at the 316th amino acid (p.316fs388x). The deleted bases are underlined in the normal sequence