Wide morphological spectrums of renal neoplasms with TSC/mTOR, NF2, or monoallelic MUTYH germline mutation

Abstract

Advances in molecular biology techniques have led to the recognition of more molecularly defined renal entities. However, some molecular-defined renal cell carcinomas (RCC) exhibit heterogeneous morphologies. In recent years, TSC/mTOR and NF2 alterations in renal cancers have attracted considerable attention from pathologists, including several renal tumors that have been validated as different entities. The monoallelic MUTYH germline mutation has also recently been demonstrated to be a driver of tumorigenesis, which is relatively enriched in renal cancers and may predict the risk of metastasis. In the current study, we presented seven cases with TSC/mTOR alterations (two with fibromyomatous stroma, one concomitant with ELOC mutation, three eosinophilic solid and cystic RCC, and two RCC, NOS), four cases with NF2 mutations (one concomitant with FH mutation, one biphasic hyalinizing psammomatous RCC, and two RCC, NOS), and two cases with monoallelic MUTYH germline mutations (one collecting duct carcinoma and one papillary RCC). We observed that renal cancers harboring these mutations had a wide morphological spectrum. Renal neoplasms with TSC/mTOR mutations may have an indolent outcome. NF2-mutated RCC appeared to display calcification and sclerotic stroma. The identification of these renal cancers can help reduce the number of tumors diagnosed as RCC, NOS. However, whether they can be grouped into TSC/mTOR, NF2, or MUTYH -associated RCC requires further validation.