FH and neoplasm: Some specific hereditary RCC syndromes or emerging tumor types can present with unusual morphology and might have been labeled unclassified in the past before their distinct identity was known, for instance, RCC associated with fumarate hydratase (FH) gene mutations (formerly an unclassified high-grade tumor, now recognized as FH-deficient RCC) or anaplastic lymphoma kinase (ALK)-rearranged RCC (a rare entity often with morphologies that puzzled pathologists initially) [50].