Low grade oncocytic tumour of the kidney: report of 2 cases

Low-grade oncocytic tumour (LOT) of the kidney is one emerging entities included in recently published Fifth Edition WHO classification Tumours.1 It shows overlapping morphological features with oncocytoma and chromophobe renal cell carcinoma but has unique KIT negative Keratin (KRT) 7 diffuse positive immunophenotype. Herein, we describe clinical, morphological, immunohistochemical findings two LOTs. Both patients were 72-years-of age. A male female patient underwent partial nephrectomy for a 35 mm, pT1a tumour; radical 50 pT1b respectively. Macroscopically, both tumours circumscribed unencapsulated. The larger had solid tan cut surface, while smaller surface significant central cystic degeneration. Histologically, compact nested architecture composed eosinophilic cells round nuclei, inconspicuous nucleoli focal perinuclear clearing. displayed KRT expression. GATA3 (clone L50-823) was tumours. Although LOT been shown to display positivity using clone L50-823,2 our experience these that it can be negative. References 1. Amin MB, Berney DM, Compérat, EM, et al. Tumours Kidney. In: Classification Editorial Board. Tumours: Urinary Male Genital Tumours. 5th ed, vol. 8. Lyon: IARC, 2022. https://tumourclassification.iarc.who.int/chapters/36. 2. Williamson SR, Hes O, Trpkov K, characterised by genetic alterations TSC1, TSC2, MTOR or PIK3CA consistent positivity. Histopathology 2023; 82: 296–304.