Introduction. Renal neoplasms are a common disease. Differential diagnostics of different tumor subtypes for prognosis and treatment is necessary given that some of them, like renal cell oncocytomas, are benign, and others, like chromophobe renal cell carcinomas, are malignant. Unfortunately, the histological similarity between these tumors makes accurate diagnostics difficult. In some cases, additional diagnostic methods such as immunohistochemistry should be used. The aim of our study is to analyze the histological characteristics of chromophobe renal cell carcinomas and renal oncocytomas, in order to specify their pathognomonic features, allowing for the confirmation of the diagnosis.
Materials and methods. We used data from histories of disease and histological postoperative material of 198 patients with chromophobe renal cell carcinoma and renal oncocytoma. After the diagnosis was confirmed, we described the histological features of the tumors and calculated their relative prevalence amongst the renal oncocytoma and chromophobe renal cell carcinoma tissues. To conclude, we identified the histological features that are more likely to be present in the case of chromophobe renal cell carcinoma.
Conclusions. Chromophobe renal cell carcinomas are present in 31 % of our samples. Tumors are more prevalent in patients in their sixth and seventh decade. Most chromophobe renal cell carcinomas are unilateral.
Chromophobe renal cell carcinomas have a polymorphic histological structure. The classic variant of chromophobe renal cell carcinoma is more common than the eosinophilic one. A mixed variant of chromophobe renal cell carcinoma is present in a minority of cases. The most common features of ChRCC are solid and alveolar growth patterns, clear and reticular cytoplasm, raisinoid nuclei.
After comparing the relative prevalence of various histological features in renal oncocytomas to those present in chromophobe renal cell carcinomas, we are able to ascertain that chromophobe renal cell carcinomas tend to exhibit the following features significantly more often than renal oncocytomas: differing nuclear size, raisinoid nuclei, reticular cytoplasm, clear cytoplasm.
The particular features mentioned in the preceding paragraph, can be present on a small subset of the tumor tissue, and are thus, often missed during analysis, which can lead to misdiagnosis. In order to mitigate this risk, we recommend analyzing a big sample of tumor tissue and using additive methods such as immunohistochemistry with biomarkers CD 10 (56C6), CD 68 (KP1), Cytokeratin 7 (OV-TL 12/30), CD117/c-kit, Vimentin (Vim3B4), S-100 (4C4.9).
Editorial Comment to Molecular pathology of chromophobe renal cell carcinoma: A review
