Carcinoma renal papilar con polaridad reversa: revisión y reporte de un caso.

BACKGROUND: Renal papillary carcinoma with reverse polarity is a recently described condition. Due to its morphological and immunohistochemical characteristics, it is important to consider it as a variant with a better prognosis within the rest of the papillary carcinomas of the kidney. CLINICAL CASE: A 51-year-old female patient who, due to a history of COVID-19, underwent a control CT scan, where a mass measuring 2.3 cm in the long axis was identified in the left kidney. It was decided to perform a partial nephrectomy. The pathological study of the surgical specimen reported a tumor lesion measuring 1.4 cm in length, partially cystic, with a cream-colored surface and a finely papillary appearance. The histopathological study reported an encapsulated, partially cystic tumor lesion, with a papillary growth pattern, made up of cubic to columnar cells with granular eosinophilic cytoplasm and low-grade apical nuclei (reverse polarity), in addition to a lining of very thin fibrovascular septa. The immunohistochemistry was positive for GATA-3 and CK7. CONCLUSION: Through molecular studies, new subtypes of renal carcinoma with a papillary growth pattern have been recognized. The prevalence of these neoplasms is difficult to estimate due to the lack of adequate categorization. [ABSTRACT FROM AUTHOR]