A case report of a low-grade oncocytic tumour of kidney – a new and emerging entity

Background: Low-grade oncocytic tumour (LOT) is an emerging entity describing a slow growing with morphologic features overlapping between chromophobe renal cell carcinoma (ChRCC) and oncocytoma, staining positive for cytokeratin-7 negative CD117 (c-kit). This has been recently recognised in the WHO classification of tumours 5th edition 2022. Presentation: In this case report, we present 77-year-old lady who lower pole her right kidney, discovered incidentally during work up recurrent urinary tract infections. Grossly, was well circumscribed solid brown areas haemorrhage. Microscopically, neoplasm low-grade consisting small nests cells among oedematous looking stroma, large polygonal eosinophilic cytoplasm, occasional binucleate cells, perinuclear halos. Immunohistochemically, strongly diffusely cytokeratin-7, CD117. diagnosis consistent LOT favourable outcome patient. Conclusion: morphological feature other neoplasms example ChRCC however distinct immunohistochemistry profile. It thus important to be considered as part differential given its indolent nature that can impact patient’s management. References 1. Akgul M, et al. expands spectrum deserves separate classification: review 23 cases from single tertiary institute. J Clin Pathol 2021; 75: 772–775. 2. de Andrade Melo CG, kidney (CD117-negative, cytokeratin 7-positive). Surg Exp 2020: 3: 1–4. 3. Trpkov K, 7-positive): entity? Histopathology 2019; 174–184.