Classification of Renal Cell Carcinoma Based on Morphologic and Cytogenetic Correlations

Abstract

Typing or classification of renal cell carcinomas — a term introduced by Murphy and Mostofi in 1965 (1) — has been a debatable field since Grawitz (2) introduced the term hypernephroma in 1883. Grawitz postulated a hypernephrogenic origin of renal cancers, whose cells exhibit a light cytoplasm. During recent decades it has become customary to view renal cell carcinoma as a complex entity. Despite support for this idea by the World Health Organization (3) a morphological subtyping of renal cell carcinoma has not been recognized until recently. In 1986 Thoenes et al. (4) proposed a new pathomorphological subtyping of epithelial renal cell tumors, renal cell carcinoma (RCC) and adenoma (RCA), which is based on two morphological criteria, cellular characteristics and tissue characteristics. This proposal has been further refined so that 7 distinct tumor types are now recognized (Figure 1): 1) Clear cell RCC; 2) Chromophilic RCC and RCA; 3) Chromophobic RCC; 4) RCC of the Duct of Bellini; 5) Oncocytic RCC (oncocytomas); 6) Metanephroid RCA; and 7) Neuroendocrine RCC. The spindle shaped and pleomorphic type of RCC is a non-differentiated variant of the first 4 types of RCC and for that reason it is not counted independently.