Rosy Cells with a Rocky Core: Low-Grade Oncocytic Tumor with Osseous Metaplasia
Main Article Content
Keywords
low-grade oncocytic tumor, LOT, osseous metaplasia, kidney, renal
Abstract
Osseous metaplasia is rarely reported in renal neoplasms and is predominantly associated with a favorable prognosis. Low-grade oncocytic tumor (LOT) represents a novel diagnostic classification of renal neoplasms that exhibit overlapping features of oncocytomas and chromophobe renal cell carcinoma. To the best of our knowledge, there are two definitive cases of low-grade oncocytic tumors with osseous metaplasia in the English literature. We present the third case of a 52-year-old female diagnosed with a low-grade oncocytic tumor exhibiting osseous metaplasia.
References
1. Trpkov K, Williamson SR, Gao Y, Martinek P, Cheng L, Sangoi AR, et al. Low-grade oncocytic tumour of kidney (CD117-negative, cytokeratin 7-positive): A distinct entity? Histopathology. 2019;75(2):174–84. https://doi.org/10.1111/his.13865
2. Alagar JN, Firde K, Fentaw B, Amer SM, Seth A, Proca D. Charting new territory with a novel WHO provisional category: A case study of a low-grade oncocytic tumor (LOT) in the kidney. Cureus. 2025;17(1):e78132. https://doi.org/10.7759/cureus.78132
3. Akgul M, Al-Obaidy KI, Cheng L, Idrees MT. Low-grade oncocytic tumour expands the spectrum of renal oncocytic tumours and deserves separate classification: A review of 23 cases from a single tertiary institute. J Clin Pathol. 2022;75(11):772–5. https://doi.org/10.1136/jclinpath-2021-207478
4. Xie B, Li Q, Ma Q, Huang Y, Wu Z, Hu Z, et al. Clinicopathological and molecular features of so-called low-grade oncocytic fumarate hydratase-deficient renal cell carcinoma: A study of 5 cases. Virchows Arch. 2025;487(2):377–88. https://doi.org/10.1007/s00428-025-04111-8
5. Liu YJ, Ussakli C, Antic T, Liu Y, Wu Y, True L, et al. Sporadic oncocytic tumors with features intermediate between oncocytoma and chromophobe renal cell carcinoma: Comprehensive clinicopathological and genomic profiling. Hum Pathol. 2020;104:18–29. https://doi.org/10.1016/j.humpath.2020.07.003
6. Mansoor M, Siadat F, Trpkov K. Low-grade oncocytic tumor (LOT)—A new renal entity ready for a prime time: An updated review. Histol Histopathol. 2022;37(5):405–13.
7. Tan PH, Cheng L, Rioux-Leclercq N, Merino MJ, Netto G, Reuter VE, et al. Renal tumors: Diagnostic and prognostic biomarkers. Am J Surg Pathol. 2013;37(10):1518–31. https://doi.org/10.1097/PAS.0b013e318299f12e
8. Bloom TL, Gray Sears CL, Williams TR, Linfesty RL, Amling CL. Multilocular cystic renal cell carcinoma with osseous metaplasia in a 25-year-old woman. Urology. 2003;61(2):462. https://doi.org/10.1016/S0090-4295(02)02145-3
9. Hartman RJ, Helfand BT, Dalton DP. Clear cell renal cell carcinoma with osseous metaplasia: a case report. Can J Urol. 2011;18(1):5564–7.
10. Daniel WW, Jr., Hartman GW, Witten DM, Farrow GM, Kelalis PP. Calcified renal masses. A review of ten years experience at the Mayo Clinic. Radiology. 1972;103(3):503–8. https://doi.org/10.1148/103.3.503
11. Zagoria RJ, Wolfman NT, Karstaedt N, Hinn GC, Dyer RB, Chen YM. CT features of renal cell carcinoma with emphasis on relation to tumor size. Invest Radiol. 1990;25(3):261–6. https://doi.org/10.1097/00004424-199003000-00010
12. Joeckel E, Haber T, Prawitt D, Junker K, Hampel C, Thüroff JW, et al. High calcium concentration in bones promotes bone metastasis in renal cell carcinomas expressing calcium-sensing receptor. Mol Cancer. 2014;13:42. https://doi.org/10.1186/1476-4598-13-42
13. Macke RA, Hussain MB, Imray TJ, Wilson RB, Cohen SM. Osteogenic and sarcomatoid differentiation of a renal cell carcinoma. Cancer. 1985;56(10):2452–7. https://doi.org/10.1002/1097-0142(19851115)56:10<2452::AID-CNCR2820561021>3.0.CO;2-C
14. Haddad FS, Shah IA, Manné RK, Costantino JM, Somsin AA. Renal cell carcinoma insulated in the renal capsule with calcification and ossification. Urol Int. 1993;51(2):97–101. https://doi.org/10.1159/000282522
15. Wang L, Park P, Zhang H, La Marca F, Claeson A, Than K, et al. BMP-2 inhibits tumor growth of human renal cell carcinoma and induces bone formation. Int J Cancer. 2012;131(8):1941–50. https://doi.org/10.1002/ijc.27444
16. Imai N, Iwai A, Hatakeyama S, Matsuzaki K, Kitagawa Y, Kato S, et al. Expression of bone morphogenetic proteins in colon carcinoma with heterotopic ossification. Pathol Int. 2001;51(8):643–8. https://doi.org/10.1046/j.1440-1827.2001.01243.x
17. Kypson AP, Morphew E, Jones R, Gottfried MR, Seigler HF. Heterotopic ossification in rectal cancer: Rare finding with a novel proposed mechanism. J Surg Oncol. 2003;82(2):132–6. https://doi.org/10.1002/jso.10181
18. Yamasaki M, Nomura T, Mimata H, Nomura Y. Involvement of bone morphogenetic protein 2 in ossification of renal cell carcinoma. J Urol. 2004;172(2):475–6. https://doi.org/10.1097/01.ju.0000130509.34235.ef
2. Alagar JN, Firde K, Fentaw B, Amer SM, Seth A, Proca D. Charting new territory with a novel WHO provisional category: A case study of a low-grade oncocytic tumor (LOT) in the kidney. Cureus. 2025;17(1):e78132. https://doi.org/10.7759/cureus.78132
3. Akgul M, Al-Obaidy KI, Cheng L, Idrees MT. Low-grade oncocytic tumour expands the spectrum of renal oncocytic tumours and deserves separate classification: A review of 23 cases from a single tertiary institute. J Clin Pathol. 2022;75(11):772–5. https://doi.org/10.1136/jclinpath-2021-207478
4. Xie B, Li Q, Ma Q, Huang Y, Wu Z, Hu Z, et al. Clinicopathological and molecular features of so-called low-grade oncocytic fumarate hydratase-deficient renal cell carcinoma: A study of 5 cases. Virchows Arch. 2025;487(2):377–88. https://doi.org/10.1007/s00428-025-04111-8
5. Liu YJ, Ussakli C, Antic T, Liu Y, Wu Y, True L, et al. Sporadic oncocytic tumors with features intermediate between oncocytoma and chromophobe renal cell carcinoma: Comprehensive clinicopathological and genomic profiling. Hum Pathol. 2020;104:18–29. https://doi.org/10.1016/j.humpath.2020.07.003
6. Mansoor M, Siadat F, Trpkov K. Low-grade oncocytic tumor (LOT)—A new renal entity ready for a prime time: An updated review. Histol Histopathol. 2022;37(5):405–13.
7. Tan PH, Cheng L, Rioux-Leclercq N, Merino MJ, Netto G, Reuter VE, et al. Renal tumors: Diagnostic and prognostic biomarkers. Am J Surg Pathol. 2013;37(10):1518–31. https://doi.org/10.1097/PAS.0b013e318299f12e
8. Bloom TL, Gray Sears CL, Williams TR, Linfesty RL, Amling CL. Multilocular cystic renal cell carcinoma with osseous metaplasia in a 25-year-old woman. Urology. 2003;61(2):462. https://doi.org/10.1016/S0090-4295(02)02145-3
9. Hartman RJ, Helfand BT, Dalton DP. Clear cell renal cell carcinoma with osseous metaplasia: a case report. Can J Urol. 2011;18(1):5564–7.
10. Daniel WW, Jr., Hartman GW, Witten DM, Farrow GM, Kelalis PP. Calcified renal masses. A review of ten years experience at the Mayo Clinic. Radiology. 1972;103(3):503–8. https://doi.org/10.1148/103.3.503
11. Zagoria RJ, Wolfman NT, Karstaedt N, Hinn GC, Dyer RB, Chen YM. CT features of renal cell carcinoma with emphasis on relation to tumor size. Invest Radiol. 1990;25(3):261–6. https://doi.org/10.1097/00004424-199003000-00010
12. Joeckel E, Haber T, Prawitt D, Junker K, Hampel C, Thüroff JW, et al. High calcium concentration in bones promotes bone metastasis in renal cell carcinomas expressing calcium-sensing receptor. Mol Cancer. 2014;13:42. https://doi.org/10.1186/1476-4598-13-42
13. Macke RA, Hussain MB, Imray TJ, Wilson RB, Cohen SM. Osteogenic and sarcomatoid differentiation of a renal cell carcinoma. Cancer. 1985;56(10):2452–7. https://doi.org/10.1002/1097-0142(19851115)56:10<2452::AID-CNCR2820561021>3.0.CO;2-C
14. Haddad FS, Shah IA, Manné RK, Costantino JM, Somsin AA. Renal cell carcinoma insulated in the renal capsule with calcification and ossification. Urol Int. 1993;51(2):97–101. https://doi.org/10.1159/000282522
15. Wang L, Park P, Zhang H, La Marca F, Claeson A, Than K, et al. BMP-2 inhibits tumor growth of human renal cell carcinoma and induces bone formation. Int J Cancer. 2012;131(8):1941–50. https://doi.org/10.1002/ijc.27444
16. Imai N, Iwai A, Hatakeyama S, Matsuzaki K, Kitagawa Y, Kato S, et al. Expression of bone morphogenetic proteins in colon carcinoma with heterotopic ossification. Pathol Int. 2001;51(8):643–8. https://doi.org/10.1046/j.1440-1827.2001.01243.x
17. Kypson AP, Morphew E, Jones R, Gottfried MR, Seigler HF. Heterotopic ossification in rectal cancer: Rare finding with a novel proposed mechanism. J Surg Oncol. 2003;82(2):132–6. https://doi.org/10.1002/jso.10181
18. Yamasaki M, Nomura T, Mimata H, Nomura Y. Involvement of bone morphogenetic protein 2 in ossification of renal cell carcinoma. J Urol. 2004;172(2):475–6. https://doi.org/10.1097/01.ju.0000130509.34235.ef
Article Sidebar
Published
Jan 6, 2026
Article Details
How to Cite
Rosy Cells with a Rocky Core: Low-Grade Oncocytic Tumor with Osseous Metaplasia. (2026). Journal of Kidney Cancer, 13(1), 1-5. https://doi.org/10.15586/jkcvhl.v13i1.439
Section
Kidney Cancer: Case Reports
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Author Biography
Justin Tse, Department of Internal Medicine, Sutter Roseville Medical Center, Roseville, CA
Department of Internal Medicine, Resident Physician PGY-3
How to Cite
Rosy Cells with a Rocky Core: Low-Grade Oncocytic Tumor with Osseous Metaplasia. (2026). Journal of Kidney Cancer, 13(1), 1-5. https://doi.org/10.15586/jkcvhl.v13i1.439