2例伴有极向反转的乳头状肾肿瘤合并第二原发肿瘤的临床病理特征及文献复习OA

Papillary renal neoplasm with reverse polarity(PRNRP)is a rare renal tumor newly defined in the fifth edition of the World Health Organization(WHO)Classification of Urinary and Male Genital Tumours.Morphologically,PRNRP can be easily confused with other papillary renal tumors and oncocytic renal neoplasms,and the diagnostic difficulty may be further increased when it coexists with another primary renal tumor or an extrarenal malignancy.Relevant case data remain relatively limited in China.This study retrospectively analyzed 2 patients with PRNRP treated between July 2025 and April 2026.Clinical information,including medical history,imaging findings,preoperative biochemical test results,surgical procedures,tumor margin distance,intraoperative blood loss,operative duration,postoperative complications,postoperative changes in renal function,and perioperative medications,was reviewed.Hematoxylin and eosin(HE)stained and immunohistochemical stained sections were re-evaluated to assess histopathological features and immunohistochemical findings.In addition,previously published domestic and international literature was reviewed to summarize the diagnosis,differential diagnosis,and distinctive features of this tumor.The 2 patients were 75 and 71 years old,respectively.Tumor diameters were 0.2 and 1.5 cm,respectively.Patient 1 had PRNRP accompanied by an ipsilateral low-grade oncocytic tumor(LOT)of the kidney,whereas patient 2 had PRNRP accompanied by primary poorly differentiated adenocarcinoma of the colon.Immunohistochemically,tumor cells in both PRNRP cases were positive for GATA-binding protein 3(GATA3)and cytokeratin 7(CK7),negative for cluster of differentiation 117(CD117),renal cell carcinoma antigen(RCC),and vimentin,and weakly positive for alpha-methylacyl-CoA racemase(AMACR,P504S).In patient 2,the colonic carcinoma showed loss of mutL homolog 1(MLH1)expression,while mutS homolog 2(MSH2),mutS homolog 6(MSH6),and post-meiotic segregation increased 2(PMS2)were retained.Gene testing of the colonic carcinoma showed a wild-type profile.Both PRNRP lesions were staged as pT1a.During postoperative follow-up,both patients had favorable outcomes,with no recurrence or metastasis of PRNRP identified.These 2 cases demonstrate diverse patterns of PRNRP occurrence,indicating that PRNRP may arise alone,coexist with renal LOT,or occur in patients with malignant tumors of other organ systems.PRNRP is a rare renal neoplasm that shows morphological overlap with several papillary and oncocytic renal tumors and therefore represents a potential diagnostic pitfall in urinary tract pathology.In routine practice,careful assessment of histomorphological features and appropriate use of immunohistochemical markers are essential for distinguishing PRNRP from its mimics.In addition to establishing the diagnosis of the renal tumor itself,clinicians and pathologists should assess the patient's overall tumor history and remain alert to the possibility of multiple primary tumors.Thorough preoperative evaluation and individualized follow-up strategies are also warranted.This study provides additional reference data for the pathological recognition and diagnostic practice of this rare renal neoplasm.