A hybrid tumor is not officially included in the latest International Histological Classification of Kidney Tumors (WHO, 2022), however, according to the literature, a number of researchers still consider a hybrid tumor as an independent nosological unit. In this regard, the development of morphological and molecular genetic criteria for a hybrid tumor, today, is the main task in the differential diagnosis of oncocytic renal tumors.
Aim: Our aim was to carry out to identify immunohistochemical, ultrastructural features and determine the molecular profile of hybrid renal tumors.
Patients and methods: The study was performed on the surgical material of 12 patients with a hybrid tumor of the kidney. Immunohistochemical study was carried out on paraffin sections according to the standard protocol. Antibodies CK7, CD117, Cyclin D1, EpCAM, Caveolin1, EABA, and S100A1 were used. To study tumor tissues on semi-thin and ultra-thin sections, an electron microscope Philips TECNAI 12 BioTwinD-265 is used. For in situ fluorescent diagnostic detection, defined centromere probes, LSI 13/21, LSI N25 /LSI ARSA and TelVysion telomeric probe.
Results: In some cases, a hybrid tumor is represented by a solid structure of monomorphic oxyphilic cells with a characteristic immuno-, ultraphenotype and molecular profile.
Conclusion: The results of a comprehensive study confirm that the hybrid tumor is an intermediate link in the process of malignant transformation of oncocytoma into chromophobe renal cell carcinoma.
Keywords: chromophobe renal cell carcinoma; hybrid tumor; immunohistochemistry; molecular diagnostics; oncocytoma; ultrastructural study.