Here, we show that after further diagnostic validation studies, positive PAPPA2 staining can be used as an adjunct to the current diagnostic tests to aid in diagnosis, similarly to the use of stains for 2-succinocysteine alongside fumarate hydratase in hereditary leiomyomatosis and RCC-associated tumors.40 This evidence concerns the gene FH and hereditary leiomyomatosis and renal cell cancer.