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. 2026 Jun 17;19:602443. doi: 10.2147/IMCRJ.S602443

Papillary Renal Neoplasm with Reversed Polarity in a 64-Year-Old Male: A Rare Case Report and Review of the Literature

Yu Wang 1, Mengsi Zhang 1, Guangzong Su 2, Qiao Zhou 1,✉
PMCID: PMC13284039  PMID: 42339132

Abstract

Background

Papillary renal neoplasm with reversed polarity is a rare entity, with its latest definition established only in 2019. Given its rarity, with less than 100 reported cases, further characterization is needed to enhance diagnostic accuracy and inform management strategies.

Case Presentation

We report a case in a 64-year-old Chinese male with an incidentally discovered a size of 5.2cm×4.0cm left renal mass on imaging. The patient has a medical history of coronary heart disease and left lower limb numbness. Further evaluation via contrast-enhanced CT confirmed that a nodular slightly hyperdense lesion approximately 52mm*39mm in size is noted in the left kidney. He underwent a partial nephrectomy and postoperative pathology confirmed PRNRP. Under the microscope, papillary structures can be seen lining a single layer of cuboidal epithelial cells in the left renal cyst and tumor. The nucleus appears low-grade, round, reverse nuclear polarity, and the nucleolus is not obvious. The tumor has not invaded the renal parenchyma. Immunohistochemistry confirmed P504S (+), CK7 (+), CK-H (+), GATA-3 (+), E-Cadherin (+), CK20 (Partial weak+), Vimentin (−), CD10 (individual+), CA-IX (−), RCC (−), Ki-67 (Li 1%). Postoperative recovery was excellent. The patient in this case did not receive any other treatment after surgery. Through regular telephone follow-up for 3 months, the patient’s condition was good. Ultrasound examination was performed during the period, and no recurrence or metastasis was found.

Conclusion

This article presents a case of papillary renal neoplasm with reversed polarity in an elderly male patient. By reviewing the patient’s diagnosis and treatment process and revisiting relevant literature, the clinicopathological features of this tumor are elucidated to enhance understanding of this rare renal tumor. This case reinforces the distinct morphological and molecular profile of PRNRP, distinguishing it from other papillary RCC subtypes. The indolent behavior, absence of metastatic cases, and characteristic molecular profiling and immunohistochemical markers highlight the importance of accurate classification for optimal patient management. As PRNRP is recently classified, continued study is essential to refine diagnostic, therapeutic, and surveillance strategies for this rare renal neoplasm.

Keywords: papillary renal neoplasm with reverse polarity, PRNRP, immunohistochemistry, rare case, renal tumors

Introduction

In recent years, many kidney tumors with unique histological features, mixed components, or molecular variations have been independently classified.1 Many of which were once considered papillary renal cell carcinoma (PRCC),2 because PRCC ranks second in number and has a high incidence rate among the common morphological types of renal cell carcinoma, and is more common in daily life.3 Due to the poor prognosis of PRCC patients, it is crucial to distinguish and differentiate some unique and variant subtypes of kidney tumors with good prognosis from PRCC, as this involves the development of different diagnosis and treatment plans in the future. The tumor mentioned in this report is different from common renal tumors in the past, it has certain specific characteristics. Separating it and paying special attention to it can help improve understanding of it and adopt corresponding diagnostic and treatment methods.

Case Presentation

The patient is a 64-year-old male who visited Wuhan Asia General Hospital on December 29, 2025, due to “a left kidney mass discovered 3 days ago” and underwent “partial nephrectomy”. Laboratory tests, including platelet count and coagulation function, showed no abnormalities. Past medical history: coronary heart disease and left lower limb numbness. Physical examination: abdomen was flat and soft with no tenderness, and no percussion pain in the renal area. CT findings: bilateral kidneys showed normal size and morphology, with a fuzzy shadow in the perirenal region. Multiple cystic hypodense lesions were observed in both kidneys, along with a cystic slightly hyperdense lesion in the left kidney. Contrast-enhanced scans revealed no enhancement, but a nodular slightly hyperdense lesion approximately 52mm×39mm in size was noted in the left kidney. The hypodense nodules within showed moderate enhancement, while the surrounding cystic components remained unenhanced. Focal hyperdense lesions were observed in the renal calyces of both kidneys (as shown in Figure 1). Magnetic resonance examination: Single site plain scan of magnetic resonance showed a range of approximately 5.2cm×4.0cm×4.6cm (anterior posterior×left lateral×up and down diameter) short T1 and short T2 signal protrusions visible in the upper pole of the left kidney, extending outward from the contour of the kidney. The lesion showed exogenous growth with clear boundaries. Patchy solid components with slightly longer T1 and slightly longer T2 signals could be seen on the near renal side of the lesion, with a range of approximately 1.5cm×2.1cm×2.6cm (left lateral×anterior posterior×up and down diameter); Nodular short T1 and short T2 signals were observed in the lower pole of the left kidney, with a range of approximately 1.2cm× 1.4cm and clear boundaries; Multiple circular long T1 and long T2 signals were observed in both kidneys, with larger ones ranging from approximately 1.3cm×1.3cm and clear boundaries. Combined with MR plain scan, dynamic enhanced scan showed a solid mass in the upper pole of the left kidney, with no significant enhancement observed in the cystic part of the lesion, and gradual and significant enhancement observed in the solid part after enhancement; Left renal lower pole cystic lesion, no significant enhancement observed after enhancement; Multiple cystic lesions were observed in both kidneys, but no significant enhancement was observed after enhancement. Magnetic resonance single organ diffusion-weighted imaging (DWI) matched plain scan showed mild diffusion limitation of solid components in the lesion of the upper pole of the left kidney, and multiple cystic lesions in the lower pole of the left kidney and both kidneys, with no diffusion limitation observed (as shown in Figures 2 and 3).

Figure 1.

Figure 1

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CT plain scan of the kidney shows a high-density mass with a wall attached nodule in the left renal cortex, measuring 5.2×4.0 in size and protruding outward from the renal contour, with clear boundaries.

Figure 2.

Axial MRI of upper abdomen showing soft tissues on a dark background in grayscale. A grayscale axial magnetic resonance imaging slice of the upper abdomen on a dark background. The body outline forms an oval cross-section with a thin peripheral rim. Multiple soft-tissue regions of differing gray intensity occupy the central and lateral portions. Two bean-shaped structures with darker central areas are positioned symmetrically in the lower half. A rounded bright white region is present along the right edge of the image. No staining, tissue section features, magnification text, scale bar, or labels are present.

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Renal MRI TIWI weighted image shows a significant high signal mass, with wall nodules showing equal signal intensity.

Figure 3.

Axial abdominal scan: kidney shapes and dark lumens on black. A single grayscale axial radiology cross-section of the upper abdomen on a black background. The outer body contour forms an oval ring with a darker peripheral band and a lighter internal field. Two large, symmetric, kidney-shaped structures occupy the lower left and lower right portions of the frame, each containing lighter central regions and small internal bright foci. Multiple rounded and oval dark lumens are distributed across the upper half of the image, including several clustered near the top center and top right. A central posterior bony structure with a bright rim and darker internal area lies near the bottom center, with adjacent soft-tissue densities surrounding it. Additional soft-tissue structures of mixed gray intensity fill the central abdomen between the two kidney-shaped structures, including an elongated, curved dark lumen near the midline.

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T2WI weighted image of renal MRI shows a significantly low signal mass and a slightly high signal attached to the wall nodule.

Pathological examination: Upon gross examination, the left kidney cyst and tumor presented as a gray yellow dark brown kidney tissue with a size of 6cm×2.5cm× 1cm. There was a fragmented cystic wall like tissue attached to the kidney tissue with a size of 6cm×5cm×2cm and a cystic wall thickness of (0.1–0.3) cm. The outer side of the cystic wall was covered with a fat sac. In addition, a pile of free fragmented papillary tissue with a total size of 3cm×2cm×1cm was observed in the specimen bottle (as shown in Figure 4). Under the microscope, papillary structures could be seen lining a single layer of cuboidal epithelial cells in the left renal cyst and tumor. The nucleus appeared low-grade, round, and the nucleolus was not obvious. The tumor had not invaded the renal parenchyma (as shown in Figures 5–9). Immunohistochemistry showed that tumor cells exhibited: P504S (+), CK7 (+), CK-H (+), GATA-3 (+), E-Cadherin (+), CK20 (Partial weak+), Vimentin (−), CD10 (individual+), CA-IX (−), RCC (−), Ki-67 (Li 1%) (as shown in Figures 10–14).

Figure 4.

Postoperative photograph of surgically removed tissue placed on a blue examination tray. The specimen consists of multiple irregular fragments of brown to yellow tissue, including a larger mass on the left and several smaller tissue fragments distributed across the tray. Near the top center, a metal mesh sieve contains additional tissue fragments collected for examination. Areas of yellow fatty tissue are attached to portions of the specimen. Small droplets of fluid are scattered on the tray surface. A measurement ruler positioned along the bottom edge of the image provides a size reference.

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Postoperative photography of left kidney cyst and tumor for examination.

Figure 5.

Micrograph: folded papillary mucosa with pink stroma, purple nuclei, on a pale background. A micrograph shows a large, irregular, pale lumen occupying the central and right portion of the field. Multiple folded and branching papillary projections extend from the left and upper margins into the lumen. These projections contain pink connective tissue cores and are lined by a densely nucleated epithelial layer with purple nuclei. The surrounding wall on the left side contains thick, wavy pink collagenous stroma with scattered elongated nuclei, forming broad bands that curve along the lumen. Additional smaller mucosal folds and gland-like profiles are present near the lower left margin. The background outside the tissue is pale and no text labels, scale bars, or annotation marks are present.

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Staining: HE 10×10 tumor has fibrous capsule, clear boundary with surrounding tissues, and no obvious infiltration or invasion.

Figure 6.

Micrograph shows pink-purple papillary tissue fragments in clear spaces on a pale background. A micrograph shows numerous branching papillary tissue fragments distributed across the field on a pale background. The fragments form many finger-like and frond-like outlines with repeated branching and small tufted clusters. Each fragment contains a denser pink central core with a surrounding darker purple cellular rim, creating a two-tone pattern within the projections. Wide clear spaces separate the fragments, producing a lace-like arrangement of tissue islands and intervening empty areas. A thicker elongated pink band runs diagonally near the upper central region, with multiple smaller papillary projections adjacent to it. Additional clustered papillary groups occupy the lower half and right side, with scattered smaller fragments along the left edge. No scale bar, labels, arrows, or text are present.

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Staining: HE 4×10 tumor cells grow in a papillary shape around the fiber vascular axis, with branching nipples and indistinct nucleoli.

Figure 7.

A micrograph shows pink and purple branching papillary fronds lined by epithelial cells on a pale background. A micrograph displays numerous branching papillary fronds separated by broad pale spaces. The fronds stain predominantly pink with purple nuclear staining. Each frond contains a pink stromal core and is lined by a continuous layer of epithelial cells. The epithelial cells form single to locally multilayered linings along the papillary surfaces, with many round to oval, dark purple nuclei distributed throughout the lining. Multiple small clear vacuole-like spaces are present within the epithelial cytoplasm in several fronds. Scattered small red-stained elements are present within some stromal cores. No scale bar, magnification text, labels, arrows, legends, axis labels, or plotted graphs are present.

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Staining: HE 20×10 tumor cells grow in a papillary shape around the fiber vascular axis, with abundant cytoplasm and eosinophilia.

Figure 8.

Micrograph shows pink-purple papillary tissue with dense nuclei and clear spaces between fragments. A micrograph presents a pink and purple stained tissue section composed of multiple branching papillary fragments separated by broad white spaces. The papillary fragments form irregular finger-like and leaf-like projections with rounded and tapered ends. Each projection has a darker purple outer cellular rim containing many closely spaced oval to elongated nuclei. The interior of the projections contains paler pink stromal material with scattered nuclei and multiple small clear vacuole-like spaces. Several detached small tissue pieces and individual cells lie within the white spaces between larger fragments. Small red blood cell clusters are present in a few inter-fragment spaces as bright red dots and short streaks. No scale bar, labels, arrows, or text are present and the background consists of the white spaces surrounding the tissue fragments.

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Staining: Interstitial edema can be seen in the axis of HE 20×10 partial fibrovascular axis.

Figure 9.

A micrograph shows pink branching papillary fronds lined by purple epithelial nuclei on a pale background. Branching papillary fronds occupy most of the field, separated by irregular pale spaces. The fronds contain pink stromal cores with a continuous outer lining of epithelial cells. The epithelial lining forms a single layer along the papillary edges, with numerous round to oval, dark purple nuclei spaced along the surface. The cytoplasm and stromal cores stain pink to magenta, with scattered small clear vacuole-like spaces within some fronds and within the surrounding pale spaces. Small clusters of bright red blood cells are present in a few focal areas adjacent to the papillary structures. The background consists of broad pale regions between fronds, providing contrast to the densely stained papillary tissue.

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Staining: HE 40×10 papillary structure is lined with a single layer of cuboidal cells. The cytoplasm of tumor cells is delicate, and the nucleus size is basically uniform and round, far from the base and located at the top of the cytoplasm. Small nucleoli can be seen.

Figure 10.

Micrograph shows brown staining of gland-like structures on a pale background. A micrograph presents a histology section with numerous clustered gland-like epithelial structures distributed across a pale background. The epithelial groups form irregular rounded, lobulated and branching profiles with multiple small luminal spaces within many clusters. Brown immunohistochemical staining forms a continuous outline along the borders of many epithelial cells, creating ring-like and mesh-like contours around the gland-like profiles. Blue-stained nuclei are scattered throughout the epithelial clusters and within the intervening pale stromal spaces. Pale connective tissue bands separate several clusters and create larger open spaces between groups. No scale bar, axis labels, legends, arrows, or overlaid text are present.

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CK-H tumor cell membrane positive EnVision method.

Figure 11.

A micrograph shows brown-stained branching epithelial fragments with blue nuclei on a pale background. A micrograph displays multiple branching and folded tissue fragments distributed across a pale background. The fragments form irregular, frond-like and gland-like outlines with many narrow projections and curved edges. Brown staining outlines and fills much of the cellular material within these fragments, creating darker rims and patchy brown areas along the folds. Numerous small blue nuclei are scattered throughout the fragments, with additional blue nuclei and small cell clusters present in the open spaces between fragments. Several fragments contain small internal luminal spaces and slit-like gaps, while other areas show compact cellular groupings with minimal open space. No scale bar, axis markings, or text labels are present.

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P504s tumor cytoplasm positive EnVision method.

Figure 12.

Micrograph shows brown staining of gland-like structures with blue nuclei on a pale background. A micrograph shows a tissue section with immunohistochemical staining in two dominant colors: brown staining and blue nuclear staining. Numerous branching, folded and finger-like epithelial structures form interconnected gland-like profiles across the field. The brown stain outlines many epithelial cell borders and cytoplasmic regions, creating continuous and discontinuous linear rims along the edges of the gland-like structures. Blue nuclei are distributed throughout the epithelial layers and within the surrounding pale stromal areas, with nuclei varying in density between regions. The background is predominantly light, with clear spaces between adjacent epithelial profiles and pale stromal bands separating clusters of gland-like structures. No scale bar, legend, arrows, or text labels are present.

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E-Cadherin tumor cell membrane positive EnVision method.

Figure 13.

Micrograph: brown-stained branching glands, blue nuclear stain, pale background. A micrograph displays a tissue section with numerous branching and folded gland-like epithelial structures distributed across the field. The epithelial outlines and many cell borders contain dense brown staining, forming continuous rims around multiple irregular profiles. The gland-like units vary in size and shape, including elongated, curved and lobulated forms, with several structures forming complex fronds and papillary-like folds. Many profiles contain pale central spaces and some units show tightly packed epithelial folds with narrow internal clefts. Blue counterstained nuclei are scattered throughout the epithelial layers and within the intervening pale stromal areas. The background is predominantly light, with stromal spaces separating adjacent brown-stained epithelial structures. No text, scale bar, arrows, or other annotations are present.

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EnVision method for CK7 tumor cell membrane positivity.

Figure 14.

Micrograph: brown outlines on branching structures with pale blue nuclei on a light background. A micrograph with a light blue and white background contains many clustered cells with round to oval, pale blue nuclei distributed across the field. Dark brown immunostaining forms multiple branching, elongated linear structures that traverse the image in several directions. The brown-stained structures create interconnected segments with frequent bends and junctions, including thicker continuous stretches and thinner offshoots. Several brown segments partially encircle clear spaces, forming irregular looped outlines, while other segments run between and around groups of nuclei. Small, discrete brown-stained fragments and short streaks are scattered near the larger branching lines. No text labels, scale bars, arrows, legends, axes, or plotted values are present.

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Vimentin tumor cell negative, stromal positive EnVision method.

Pathological diagnosis: (left) inverted papillary renal tumor.

Follow up: The patient in this case did not receive any other treatment after surgery. Through regular telephone follow-up for 3 months, the patient’s condition was good. Ultrasound examination was performed during the period, and no recurrence or metastasis was found.

Discussion

In 1997, Delahunt and Eble subdivided papillary renal cell carcinoma (PRCC) into type 1 and type 2,4 a concept that was previously recognized in the World Health Organization (WHO) classification.5 Type 1 papillary renal cell carcinoma shows a monolayer of papillary lining cells with sparse cytoplasm, while type 2 papillary renal cell carcinoma has papillary lining cells with abundant eosinophilic cytoplasm and higher nucleolar grading.4 However, due to the fact that many kidney tumors often contain a mixture of two types of tumors, and the classification of type 1 and type 2 tumors does not affect patient prognosis, it is not appropriate to classify PRCC into two categories. The new 2022 WHO classification does not recommend classifying PRCC into type 1 and type 2,6 as some cases of papillary renal cell carcinoma are neither type 1 nor type.7 In addition to the typical papillary renal cell carcinoma (PRCC) mentioned above and some renal cell carcinomas with special molecular mutations and papillary or tubular papillary structures, such as MiT family translocation renal cell carcinoma8 and fumarate hydratase (FH) deficiency renal cell carcinoma,9 there are many series of cases that are difficult to classify and are tentatively defined as “mixed papillary renal cell carcinoma”.10,11 But the temporary arrangement is only temporary, and it always needs to be reclassified and renamed uniformly. Recently, the Cancer Genome Atlas (TCGA) study revealed that type 2 papillary renal cell carcinoma is an heterogeneous group composed of at least three molecular subtypes. Some cases exhibit more invasive biological behavior, while others show inertia.12,13 So, how to define it as neither Type 1 nor Type 2? How to classify subtypes based on different clinical manifestations in type 2?Some scholars have proposed that papillary renal cell carcinoma rich in eosinophilic cytoplasm can be directly defined as “eosinophilic renal cell carcinoma”, which may encompass any adrenal cortex cell with eosinophilic cytoplasm, regardless of its nuclear morphology.14–17 However, this approach is too general, as some tumor subgroups within these “eosinophilic renal cell carcinomas” exhibit unique histological and clinical features, characterized by low-grade karyotype features, single-layer cells, mild atypical nuclei, and abundant eosinophilic cytoplasm. The nuclei are arranged linearly away from the base, and the clinical course is inert with a good prognosis. There is currently no unified definition for this type of variant. So, since there is no unified definition, there are different opinions. Various literature journals describe this type of tumor as “eosinophilic papillary renal cell carcinoma”,18 “adult papillary renal tumor with eosinophils”,19 “papillary renal cell carcinoma with eosinophils and non overlapping low-grade nuclei”,20 “eosinophilic papillary renal cell carcinoma with inverted karyotype”,21 “polar inverted papillary renal tumor (PRNRP)”,22 as well as eosinophilic like PRCC,23 type 4/low-grade eosinophilic PRCC,7 or type D renal papillary adenoma.24 However, due to the lack of clear morphological features or homologous immunohistochemical markers, how to accurately identify vague features such as “rich eosinophilic cytoplasm” and “mild nuclear atypia” makes these terms lack persuasiveness. In 2019, Al Obaidy et al reviewed these reports and noted the existence of a subgroup in which the nuclei of tumors were located at the top of the cell and co expressed GATA3 and L1CAM, making the tumor easy to identify; Based on this, considering its inactive course, they named it Polar Flipped Papillary Renal Tumor (PRNRP).20 Afterwards, they found that KRAS mutations frequently occurred in this type of tumor,25 further confirming the specificity of this tumor. This article describes a variant subtype of papillary renal cell carcinoma (PRCC) encountered in daily work-polarized inverted papillary renal tumor (PRNRP).

Firstly, let us understand from a clinical perspective the inverted papillary renal tumor. Zhang Y reviewed 11 published case reports and reported 97 cases of the disease, including 56 males and 41 females. Among them, 31 cases occurred in the left kidney, 43 cases occurred in the right kidney, and 23 cases had complications in both kidneys. The patients are aged between 35 and 82 years old. The lesion range generally ranges from a diameter of 0.8cm to 8.5cm, with an average of 2.1cm. The World Health Organization/International Society of Urology Pathology (ISUP) describes the disease as having a low nuclear grading, with most reported cases of PRNRP being staged as pT1.21

Secondly, we will explore the inverted papillary renal tumor from a pathological perspective. It usually presents as cystic, with microscopic features of loose papillary structures, single-layer arrangement of tumor cells, eosinophilic cytoplasm, and a nucleus located at the pole opposite the basement membrane. According to the grading system of the World Health Organization/International Association of Urological Pathology, this disease is classified as low-grade and has a good prognosis.26 In addition to its unique cellular morphology and structure, PRNRP also exhibits the following characteristics in immunohistochemistry: GATA3, CK7, and L1CAM positive, CD117 negative, and PAX-8 positive.27–29 There are also literature reports that the disease presents as Vimentin negative, CD10 and AMACR weakly positive locally. As long as it is completely removed, there are currently no reported cases of metastasis, recurrence, or death.30 In addition to immunohistochemistry, molecular testing can also diagnose inverted papillary kidney tumors.74% of inverted papillary kidney tumors exhibit KRAS gene mutations,25,29 while KRAS gene mutations are less common in other kidney tumors.25,29,31

Previously, the naming origin and development, microscopic structural characteristics, immunohistochemistry, and molecular detection diagnosis of papillary renal tumors with polar inversion were explained. Now, based on the article by H.Y. Chang,32 we summarize several diagnostic criteria for papillary renal tumors with polar inversion: ① Significantly prominent thin papillary or tubular papillary growth; ② Localized or diffuse interstitial vitrification; ③ Cytoplasmic eosinophilia; ④ The tumor cell nuclei are neatly arranged at the top of the cytoplasm, far from the basement membrane, it exhibits “reverse polarity” characterized by uniform size and low nuclear grade. The appearance of these four manifestations under the microscope suggests the possibility of a papillary renal tumor with polar inversion. Further immunohistochemistry and molecular testing can confirm and consolidate the preliminary judgment. In this case, consistent with what was mentioned in previous literature, we observed under the microscope that the left kidney cyst and tumor had papillary structures lined with a single layer of cuboidal epithelial cells, and the nucleus appeared low-grade, round, with indistinct nucleoli. The tumor did not invade the renal parenchyma. Immunohistochemistry showed that tumor cells exhibited: P504S (+), CK7 (+), CK-H (+), GATA-3 (+), E-Cadherin (+), CK20 (Partial weak+), Vimentin (−), CD10 (individual+), CA-IX (−), RCC (−), Ki-67 (Li 1%). The HE staining microscopy and immunohistochemistry results both indicate a polarized inverted papillary kidney tumor. Although it is recommended that the patient undergo molecular testing in the future, the patient refuses. However, our preliminary diagnostic opinion is consistent with the consultation opinion of other hospitals, and both tend to favor a polarized inverted papillary kidney tumor. Of course, the lack of KRAS mutation analysis may lead to limitations in this case report. Moreover, we have only encountered this one case so far, and our conclusion is relatively singular.

Currently, there is a lack of literature describing whether PRNRP has any hereditary predisposition. There has also been little discussion on the optimal treatment approach for PRNRP, likely due to its recent recognition in the literature and its generally indolent clinical behavior. As a result, most studies focus primarily on molecular, histologic, and immunophenotype characterization of this RCC subtype rather than treatment course. Of course, the emphasis of each literature is different. In our case, the absence of end-stage renal disease (ESRD) is notable, as many renal tumors, particularly cystic neoplasms, are frequently identified in patients with ESRD due to alterations in the renal microenvironment.33–35 Acquired cystic kidney disease (ACKD) develops in a significant proportion of ESRD patients–ranging from 8–95% in some studies36,37 in dialysis patients and increases the risk of cystic renal neoplasms. Incidence of renal cancers is approximately 50 times greater in ACKD patients than in the general population.38,39 Cystic neoplasms observed in ESRD include acquired cystic disease-associated renal cell carcinoma (ACDRCC), clear cell papillary renal tumor and pRCC.35,40–42 In contrast, ESRD patients without ACKD are less prone to developing cystic neoplasms. The lack of ESRD in our patient suggests that the existence of this tumor is unlikely driven by the same environmental or systemic factors that contribute to cystic neoplasms in ESRD patients.43

Our case underscores the need for further studies to elucidate the potential biological links between these rare renal neoplasms and refine diagnostic and therapeutic approaches.

Conclusion

In conclusion, papillary renal neoplasm with reversed polarity (PRNRP) is a rare and distinct subtype of renal tumor that presents unique diagnostic and treatment challenges. Although it generally has a favorable prognosis, its rarity highlights the need for further research to improve our understanding and management of this rare cancer. More studies are required to refine diagnostic criteria, treatment protocols, and explore its molecular mechanisms. Current management often follows guidelines for renal cell carcinoma, but tailored approaches based on PRNRP’s unique characteristics could enhance patient outcomes. Long-term studies will be essential to assess the effectiveness of targeted therapies and refine surveillance strategies.

Acknowledgments

We thank our radiology and pathology teams for their support.

Funding Statement

No financial support received.

Ethical Approval

The study was performed at The Department of Pathology, Wuhan Asia General Hospital, Wuhan, China. Wuhan Asia General Hospital Ethical Committee approved the study (Approval number: WAGHMECLW-2025008). Institutional ethical approval was not required for publication of the cases.

Consent for Publication

Written informed consent has been provided by the patient to have the case details and any accompanying images published.

Disclosure

The authors declare no conflicts of interest in this work.

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