{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,5]],"date-time":"2026-11-05T13:22:13Z","timestamp":1793884933063,"version":"4.8.0"},"reference-count":24,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"12","funder":[{"name":"UPMC\/Pitt Department of Pathology Internal Grant"}],"content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2025,12]]},"abstract":"<jats:p>\n                    Perinephric myxoid pseudotumor of fat (PMPTF) is a recently characterized lesion typically associated with non-neoplastic renal disease. Its pathogenesis is thought to result from chronic renal \u201cirritation,\u201d either due to mass effect from renal carcinoma or inflammation related to benign renal conditions. Prompted by several cases arising in the absence of underlying renal pathology, we conducted a multi-institutional study of 29 mass-forming cases with detailed clinical, histologic, and molecular characterization. We also reviewed 79 published cases to place our findings in a broader context. Histologic slides were reviewed for morphologic and immunohistochemical features. Clinical and follow-up data were obtained through retrospective chart review. The mean age was 67 years (range: 35 to 82), with a strong male predominance (M:F=13.5:1). The average tumor size was 10.3\u00a0cm. Liposarcoma was the most common initial diagnosis (n=20). Twelve patients (42%) had non-neoplastic renal disease, 7 (24%) had both non-neoplastic disease and renal cell carcinoma, one (3%) had renal cell carcinoma only, and 9 (31%) had no renal pathology. Histologically, lesions showed mature fat with scattered bland spindle to stellate cells, chronic inflammation, lymphoid aggregates, myxoid change, fat necrosis, hemosiderin, and prominent vasculature; extramedullary hematopoiesis was rare. All tested 28 cases were negative for\n                    <jats:italic toggle=\"yes\">MDM2<\/jats:italic>\n                    amplification by FISH. Comprehensive targeted NGS (Oncomine) and whole transcriptome sequencing (n=4) did not reveal any pathogenic alterations. Follow-up (n=28; mean, 20 months) showed stable or no disease in 24 cases; 3 patients died of unrelated causes, and one from postoperative complications. PMPTF is a benign, mass-forming lesion that mimics malignancy, particularly well-differentiated liposarcoma. Its occurrence in patients without identifiable renal pathology suggests alternative etiologies. Lack of genomic alterations supports its non-neoplastic nature. Accurate recognition is critical to prevent overtreatment. PMPTF may represent an early-stage reactive process within a broader spectrum of adipose tissue remodeling that includes renal replacement lipomatosis.\n                  <\/jats:p>","DOI":"10.1097\/pas.0000000000002467","type":"journal-article","created":{"date-parts":[[2025,9,4]],"date-time":"2025-09-04T05:00:10Z","timestamp":1756962010000},"page":"1315-1325","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":5,"title":["Perinephric Myxoid Pseudotumor of Fat"],"prefix":"10.1097","volume":"49","author":[{"given":"Azfar","family":"Neyaz","sequence":"first","affiliation":[{"name":"Department of Pathology, University of Pittsburgh, Pittsburgh, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John S.A.","family":"Chrisinger","sequence":"additional","affiliation":[{"name":"Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dimitrios","family":"Korentzelos","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Pittsburgh, Pittsburgh, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gayathri Devi","family":"Jalluri","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of Pittsburgh, Pittsburgh, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rana","family":"Naous","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Pittsburgh, Pittsburgh, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abigail I.","family":"Wald","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Pittsburgh, Pittsburgh, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Veronica","family":"Ulici","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sintawat","family":"Wangsiricharoen","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Oregon Health and Science University, Portland, OR"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ali","family":"Alani","sequence":"additional","affiliation":[{"name":"Department of Pathology, Baylor University Medical Center, Dallas, TX"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Douglas","family":"Rottmann","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Michigan, Ann Arbor, MI"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carina A.","family":"Dehner","sequence":"additional","affiliation":[{"name":"Department of Pathology, Indiana University School of Medicine, Indianapolis, IN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Josephine K.","family":"Dermawan","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Cleveland Clinic, Cleveland, OH"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kyle","family":"Perry","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Michigan, Ann Arbor, MI"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4751-7678","authenticated-orcid":false,"given":"Ivy","family":"John","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Pittsburgh, Pittsburgh, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","published-online":{"date-parts":[[2025,9,5]]},"reference":[{"key":"R1-20251112","doi-asserted-by":"crossref","first-page":"1196","DOI":"10.1038\/modpathol.2009.84","article-title":"Pseudosarcomatous fibroblastic\/myofibroblastic proliferation in perinephric adipose tissue adjacent to renal cell carcinoma: a lesion mimicking well-differentiated liposarcoma","volume":"22","author":"Tanas","year":"2009","journal-title":"Mod Pathol"},{"key":"R2-20251112","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/j.humpath.2019.02.005","article-title":"Perinephric myxoid pseudotumor of fat: a distinctive pseudoneoplasm most often associated with non-neoplastic renal disease","volume":"87","author":"Dashti","year":"2019","journal-title":"Hum Pathol"},{"key":"R3-20251112","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1097\/PAS.0000000000001968","article-title":"Myxoid pseudotumor involving the renal sinus: clinicopathologic study of 33 cases supporting a distinct benign non-neoplastic lesion","volume":"47","author":"Hogan","year":"2023","journal-title":"Am J Surg Pathol"},{"key":"R4-20251112","doi-asserted-by":"crossref","first-page":"105681","DOI":"10.1016\/j.humpath.2024.105681","article-title":"Perinephric myxoid pseudotumor of fat: a series of 13 cases and literature review","volume":"154","author":"Wu","year":"2024","journal-title":"Hum Pathol"},{"key":"R5-20251112","doi-asserted-by":"crossref","first-page":"1820","DOI":"10.1007\/s00261-022-03662-7","article-title":"Perinephric myxoid pseudotumor of fat: a multimodality imaging case series","volume":"48","author":"Lee","year":"2023","journal-title":"Abdom Radiol"},{"key":"R6-20251112","doi-asserted-by":"crossref","first-page":"382","DOI":"10.1016\/j.ajur.2022.04.007","article-title":"Perinephric myxoid pseudotumor of fat in a young patient with a horseshoe kidney complicated by an obstructing renal calculus","volume":"10","author":"Liu","year":"2023","journal-title":"Asian J Urol"},{"key":"R7-20251112","doi-asserted-by":"crossref","first-page":"3107","DOI":"10.1007\/s00261-024-04294-9","article-title":"Imaging features of perinephric myxoid pseudotumors of fat","volume":"49","author":"Broski","year":"2024","journal-title":"Abdom Radiol"},{"key":"R8-20251112","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1177\/10668969231188894","article-title":"Myxoid pseudotumor changes affecting the distal ureter associated with urothelial carcinoma in situ","volume":"32","author":"Ortiz-Rey","year":"2024","journal-title":"Int J Surg Pathol"},{"key":"R9-20251112","doi-asserted-by":"crossref","first-page":"106775","DOI":"10.1016\/j.crad.2024.106775","article-title":"Imaging appearances of perinephric myxoid pseudotumor of fat (PMPF)","volume":"81","author":"Sugi","year":"2025","journal-title":"Clin Radiol"},{"key":"R10-20251112","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1016\/j.clinimag.2020.06.041","article-title":"Perinephric myxoid pseudotumor of fat: a very rare entity that can mimic a renal cyst and retroperitoneal liposarcoma on imaging","volume":"69","author":"Chen","year":"2021","journal-title":"Clin Imaging"},{"key":"R11-20251112","doi-asserted-by":"crossref","first-page":"1108","DOI":"10.1111\/his.14382","article-title":"Perinephric myxoid pseudotumour of fat - first described case in allograft kidney, a mimicker of malignancy","volume":"79","author":"Thoeni","year":"2021","journal-title":"Histopathology"},{"key":"R12-20251112","first-page":"3640167","article-title":"Renal replacement lipomatosis presenting in the setting of ureteral stricture with absence of renal calculus disease","volume":"2021","author":"Collins","year":"2021","journal-title":"Case Rep Pathol"},{"key":"R13-20251112","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1093\/jjco\/hyac038","article-title":"Renal transplants with perinephric myxoid pseudotumor of fat mimicking malignancy","volume":"52","author":"Pham","year":"2022","journal-title":"Jpn J Clin Oncol"},{"key":"R14-20251112","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1007\/s13730-022-00746-7","article-title":"Rare perinephric myxoid pseudotumor of fat causing ureteropelvic junction obstruction: a case report","volume":"12","author":"Amato","year":"2023","journal-title":"CEN Case Rep"},{"key":"R15-20251112","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1111\/his.15210","article-title":"Lesson of the month: perinephric myxoid pseudotumor of fat co-occurring with polycystic kidney disease","volume":"85","author":"Kallen","year":"2024","journal-title":"Histopathology"},{"key":"R16-20251112","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1186\/s13000-025-01615-4","article-title":"Perinephric myxoid pseudotumor of fat - histopathological and molecular characterization of 3 cases after renal transplantation","volume":"20","author":"Schnoz","year":"2025","journal-title":"Diagn Pathol"},{"key":"R17-20251112","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1111\/j.1467-789X.2009.00623.x","article-title":"Subcutaneous and visceral adipose tissue: structural and functional differences","volume":"11","author":"Ibrahim","year":"2010","journal-title":"Obes Rev"},{"key":"R18-20251112","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1210\/en.2017-00651","article-title":"Inflammation and fibrosis in perirenal adipose tissue of patients with aldosterone-producing adenoma","volume":"159","author":"Wu","year":"2018","journal-title":"Endocrinology"},{"key":"R19-20251112","doi-asserted-by":"crossref","first-page":"594","DOI":"10.1002\/gcc.20445","article-title":"Assessment of the clinical and molecular impact of different cytogenetic subgroups in a series of 272 lipomas with abnormal karyotype","volume":"46","author":"Bartuma","year":"2007","journal-title":"Genes Chromosomes Cancer"},{"key":"R20-20251112","first-page":"1361","article-title":"The pathology of renal lipomatosis: (section of urology)","volume":"31","author":"Dukes","year":"1938","journal-title":"Proc R Soc Med"},{"key":"R21-20251112","doi-asserted-by":"crossref","first-page":"1087","DOI":"10.2214\/ajr.130.6.1087","article-title":"Replacement lipomatosis of the kidney","volume":"130","author":"Ambos","year":"1978","journal-title":"AJR Am J Roentgenol"},{"key":"R22-20251112","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1259\/bjr\/31723131","article-title":"Case report: renal replacement lipomatosis associated with renal transplantation","volume":"78","author":"Chang","year":"2005","journal-title":"Br J Radiol"},{"key":"R23-20251112","doi-asserted-by":"crossref","first-page":"754","DOI":"10.1148\/radiology.215.3.r00jn41754","article-title":"Case 23: replacement lipomatosis of the kidney","volume":"215","author":"Karasick","year":"2000","journal-title":"Radiology"},{"key":"R24-20251112","doi-asserted-by":"crossref","first-page":"bcr2014208701","DOI":"10.1136\/bcr-2014-208701","article-title":"Renal replacement lipomatosis of the right kidney","volume":"2015","author":"Ratkal","year":"2015","journal-title":"BMJ Case Rep"}],"container-title":["American Journal of Surgical Pathology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.lww.com\/10.1097\/PAS.0000000000002467","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,11,12]],"date-time":"2025-11-12T06:00:41Z","timestamp":1762927241000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.lww.com\/10.1097\/PAS.0000000000002467"}},"subtitle":["A Series of 29 Cases Demonstrating Inconsistent Associations With Underlying Kidney Disease"],"short-title":[],"issued":{"date-parts":[[2025,9,5]]},"references-count":24,"journal-issue":{"issue":"12","published-print":{"date-parts":[[2025]]}},"URL":"https:\/\/doi.org\/10.1097\/pas.0000000000002467","relation":{},"ISSN":["0147-5185","1532-0979"],"issn-type":[{"value":"0147-5185","type":"print"},{"value":"1532-0979","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,5]]},"assertion":[{"value":"2025-06-09","name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2025-08-09","name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}}]}}