Renal cell carcinoma (RCC) is defined as a group of malignancies arising from the epithelium of the renal tubules (WHO) (Moch H, Humphrey P, Ulbright T, Reuter V, WHO classification of tumours of the urinary system and male genital organs, 4th edn. IARC Press, Lyon, 2016). Although RCCs can be completely removed surgically in many cases, distant metastasis is common and may be observed even at an early stage of the disease. The classification of renal tumor had been traditionally determined according to the morphological features, such as the cytological appearance and architecture of tumor cells, and the application of immunohistochemistry, electron microscopy, and cytogenetics resulted in significant advances in the classification of RCC. Recently, many genetic aberrations of kidney tumors have been elucidated, and the genetic features have also become major criteria for the classification of some tumors. RCCs also occur in several inherited cancer syndromes, such as von Hippel-Lindau disease. Therefore, the current classification of kidney tumors is based on genetic difference as well as morphological characteristics (Moch H, Humphrey P, Ulbright T, Reuter V, WHO classification of tumours of the urinary system and male genital organs, 4th edn. IARC Press, Lyon, 2016). Furthermore, some new disease entities have been proposed recently. This chapter aims to describe the histological, immunohistochemical, and genetic characteristics of RCCs that are useful for the differential diagnosis.
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