Author(s)' Reply - Anaplastic Sarcoma of Kidney and DICER1.

Abstract

Thank you for your interest and comments regarding our manuscript on an anaplastic sarcoma of the kidney (ASK) with ganglioneuroblastic differentiation. As our knowledge of DICER 1-associated tumors continues to evolve, more cases have described neuroepithelial differentiation in different types of tumors after our initial report. Outside of the central nervous system, the cases with neuroepithelial differentiation included cervical and unusual congenital sacrococcygeal teratoid tumor. However, our report is the first to identify these morphological features within an ASK. As indicated, heterologous lines of morphological differentiation including cartilaginous and rhabdomyosarcomatous are well described observations within DICER1-assocated family of tumors. Unlike the other DICER1-associated tumors, our case did not display any rhabdomyosarcomatous differentiation despite careful histological examination and further investigation by immunohistochemical staining for desmin and myogenin. Chondroid differentiation has also been described in ASKs, although these elements were not present in our case. Consistent with previous reports, our tumor displayed aberrant p53 immunohistochemistry, but molecular analysis did not reveal any mutation in TP53. This event has been described by Wu et al.; six of the 9 ASKs with DICER1 mutations tested in their paper had aberrant p53 immunohistochemistry, but only 3 had TP53 mutations. Regardless, we agree that DICER1 mutational testing should be considered in tumors showing heterologous differentiation, especially those that display neuroepithelial, rhabdomyosarcomatous, cartilaginous, and/or anaplastic elements. Additionally, identifying these morphological patterns is important and can help in the recognition of recurrent tumors. Declaration of Conflicting Interests