Papillary Renal Neoplasm With Reverse Polarity: A Clinicopathologic Study of 7 Cases

Abstract

Papillary renal neoplasm with reverse polarity is a form of recently described tumor. These tumors are defined by GATA3 positivity, negative vimentin staining, and the presence of both papillary structures and a layer of eosinophilic cells with apical nuclei and a granular cytoplasm. In the present report, we review 7 cases of papillary renal neoplasm with reverse polarity that were GATA3+ and vimentin−, consistent with past reports. In all 7 of these cases, we found that these tumors were additionally positive for 34βE12. All 7 of these tumors were categorized as stage pT1. On histological examination, these tumors exhibited branching papillae with apical nuclei. All 7 of these patients were alive on most recent follow-up, with 6 being disease free and one having developed prostate cancer. Together, this overview of 7 additional cases of papillary renal neoplasm with reverse polarity offers further insight into this rare and poorly understood disease.

Clinicopathological and molecular characterisation of papillary renal neoplasm with reverse polarity and its renal papillary adenoma analogue

“…In agreement with previous studies, 8–12 the 10 PRNRPs identified in our cohort presented with small tumour size, low pT stage, low WHO/ISUP nuclear grade and a very indolent clinical outcome. There was no recurrence or metastasis noted after complete surgical excision.…”

“…Although Kim et al . reported four cases with WHO/ISUP grade 3 nuclei, 10 our results and other studies only found low‐grade nuclei in PRNRP 8,9,11,12 . Based on these findings, we propose the following histopathological criteria for the diagnosis of PRNRP: (1) predominant thin papillary or tubulopapillary growth, (2) focal or diffuse stromal hyalinisation, (3) eosinophilic, finely granular cytoplasm and (4) low‐grade (WHO/ISUP grades 1–2) apical nuclei.…”

“…The tumour is diffusely positive for GATA3 immunohistochemically and harbours recurrent KRAS missense mutations clustered at codon 12, verifying the distinction from other renal cell neoplasms 8–11 . Also, all previously reported PRNRP cases were low‐staged with a very good prognosis and there was no recurrence or metastasis noted with the longest follow‐up of 222 months 5–12 . Therefore, it is clinically impactful to differentiate PRNRP from PRCC, especially from type 2 PRCC, given the generally poor outcome of the latter.…”

“…Immunohistochemically, nine PRNRPs showed diffuse and strong GATA3 expression and one case exhibited moderate staining on 80% of the tumour cells. Diffuse and strong GATA3 expression was noted in 94% (32 of 34) of the PRNRP cases in the previous literature, while focal (30% and 50% of the tumour cells) weak to moderate expression was only seen in two 8,11,12 . GATA3 expression is seen in distal nephrons and urothelium in the urinary system, and is an unusual finding for renal cell tumours 27 .…”

“…demonstrated that hyalinisation of the papillae and peritumoural lymphoid aggregation were significantly more frequent in PRNRP than in PRCC 10 . Other minor morphological findings, including cystic change, oedematous papillae with cystically dilated tips, aggregates of foamy histiocytes in the papillae, eosinophilic hobnail cells, cytoplasmic vacuoles, pseudostratification, multinucleation and intracytoplasmic haemosiderin, were reported in a small subset of cases 8–12 . Psammoma body, mitotic figure or necrosis were absent.…”