Neoplasia papilar de polaridad inversa: un nuevo subtipo de tumor renal de buen pronóstico / Papillary renal cell neoplasm with reverse polarity: A new subtype of renal tumour with favorable prognosis

Introducción: La neoplasia papilar renal de polaridad inversa (NPRPI) ha sido recientemente reconocida como una entidad separada de la clasificación tradicional de los carcinomas papilares de células renales por sus peculiares características histopatológicas, inmunofenotípicas y moleculares, y un comportamiento indolente. Material y métodos: En este trabajo aportamos 6 nuevos casos y realizamos una revisión de la literatura publicada al respecto hasta el momento actual, recopilándose un total de 104 casos. Resultados: Nuestros casos de NPRPI corresponden a 5 hombres y una mujer, con edades comprendidas entre los 47 y los 91 años. En 5 casos la NPRPI resultó un hallazgo incidental en piezas de nefrectomía indicada por la presencia de otro tumor renal y en uno la NPRPI fue el motivo de la intervención quirúrgica. Nuestros casos presentan tamaños entre los 2 y los 13mm, y una histología papilar con revestimiento en monocapa de células eosinófilas con núcleos de bajo grado en localización apical. Inmunohistoquímicamente muestran una constante positividad para GATA3 y negatividad para vimentina. Se identificaron mutaciones en KRAS en el 50% de ellos. Tras un seguimiento comprendido entre uno y 60 meses, 5 de los pacientes seguían vivos sin recurrencia o metástasis y uno falleció a causa de un carcinoma urotelial. Conclusiones: Nuestros casos concuerdan con las características clínicas y patológicas descritas en los publicados hasta el momento. Aportamos la primera serie nacional y corroboramos la existencia de unos criterios diagnósticos definidos y constantes que permiten considerar la NPRPI como una entidad propia distintiva. (AU)

Introduction: Papillary renal cell neoplasm with reverse polarity (PRNRP) has recently been recognized as an entity separate from the traditional classification of papillary renal cell carcinomas, due to its specific histopathological, immunophenotypic and molecular characteristics, as well as its indolent behavior . Material and methods: We provide 6 new cases and a review of the literature published until the present time, which comprises a total number of 104 cases. Results: Our PRNRP cases correspond to 5 men and one woman aged between 47 and 91 years. In 5 of the 6 cases, the PRNRP was an incidental finding in nephrectomy specimens. Nephrectomy had been indicated due to the presence of another renal tumor, except for one case, in which surgical intervention was indicated due to PRNRP. Our cases present mass sizes between 2 and 13mm, as well as papillary histology with a monolayered lining of eosinophilic cells with low-grade nuclei in apical location. Immunohistochemically, they show a constant positivity for GATA3 and negativity for vimentin. KRAS mutations were identified in 50% of our cases. After a follow-up ranging between one and 60 months, 5 of the cases were still alive without recurrences or metastases, and one died from urothelial carcinoma. Conclusions: Our cases agree with the clinical and pathological characteristics described in the PRNRP cases published to date. With the present study, we provide the first series of national cases corroborating the existence of well-defined and constant diagnostic criteria that allow PRNRP to be considered as a distinctive entity. (AU)

Papillary renal cell neoplasm with reverse polarity: A new subtype of renal tumour with favorable prognosis.

INTRODUCTION: Papillary renal cell neoplasm with reverse polarity (PRNRP) has recently been recognized as an entity separate from the traditional classification of papillary renal cell carcinomas, due to its specific histopathological, immunophenotypic and molecular characteristics, as well as its indolent behavior. MATERIAL AND METHODS: We provide 6 new cases and a review of the literature published until the present time, which comprises a total number of 104 cases. RESULTS: Our PRNRP cases correspond to 5 men and one woman aged between 47 and 91 years. In 5 of the 6 cases, the PRNRP was an incidental finding in nephrectomy specimens. Nephrectomy had been indicated due to the presence of another renal tumor, except for one case, in which surgical intervention was indicated due to PRNRP. Our cases present mass sizes between 2 and 13 mm, as well as papillary histology with a monolayered lining of eosinophilic cells with low-grade nuclei in apical location. Immunohistochemically, they show a constant positivity for GATA3 and negativity for vimentin. KRAS mutations were identified in 50% of our cases. After a follow-up ranging between one and 60 months, 5 of the cases were still alive without recurrences or metastases, and one died from urothelial carcinoma. CONCLUSIONS: Our cases agree with the clinical and pathological characteristics described in the PRNRP cases published to date. With the present study, we provide the first series of national cases corroborating the existence of well-defined and constant diagnostic criteria that allow PRNRP to be considered as a distinctive entity.