HISTOLOGICAL EVALUATION OF RENAL CELL CARCINOMA

I. Cell Type, Histologic Organization, Grading and Their Relationships

Abstract

Renal cell carcinoma has a very wide range of structual variation: the microscopic features varies not only from case to case, but also from area to area in the same case. This can be shown when large sections or multiple sections are examined from the same case. Nevertheless, many histopathologic classifications have been proposed which inevitably have brought about nothing but confusion and obscured the unifying features of renal cell carcinoma.
From January 1957 to 1980, 162 patients with renal cell carcinoma were operated (of whom 160 patients had been nephrected, 2 patients had been punched biopsy) at the Jikei University Hospital and related hospitals.
The tumors were classified by cell type, according to cytoplasmic appearance: clear cell type, granular cell type, mixed cell type, and spindle cell type. The tumors were also classified by histologic structures: alveolar pattern, tubular pattern, cystic pattern, papillary pattern, and trabecular pattern. Each tumor was assigned a histologic grade on the basis of degree of nuclear atypism and structual atypism. Stage classification were made, using the method of Robson.
Analysis of cell type for 162 patients showed that there were 70 (43%) clear cell type, 20 (12%) granular cell type, 44 (27%) mixed cell type, 28 (17%) spindle cell type. Histologic structures were analysed and showed that there were 94 (58%) single histologic pattern (pure structual component), 47 (29%) multiple histologic pattern (mixed structual component) and 21 (13%) anaplastic pattern. In single histologic pattern, 86 (92%) alveolar pattern, 3 (3%) papillary pattern, 3 (3%) tubular pattern, and 2 (2%) cystic pattern. In multiple histologic pattern, there were 18 (38%) alveolotubular pattern, 13 (28%) alveolocystic pattern, 7 (15%) alveolotubulocystic pattern, 6 (13%) tubulocystic pattern, 2 (4%) alveolotrabecular pattern, 1 (2%) papillocystic pattern.
Four categories of tumor grading were used: 33 (20%) grade I, 63 (39%) grade II, 50 (31%) grade III, and 16 (10%) grade IV. In addition, four pathologic stages were used: 60(37%) stage I, 38 (24%) stage 2, 31 (19 %) stage 3, and 33 (20%) stage 4.
In patients with renal cell carcinoma, the relationship between cell and grade was that patients with clear cell type had a higher incidence of low grade tumor than those with spindle cell type. Patients with granular cell type and mixed cell type had a large percentage of intermediate grade (grade II and grade III). A combination of cell type and pathologic stage demonstrated that most patients with clear cell type had low stage tumor, on the other hand, most patients with spindle cell type had high stage tumor, and patients with granular cell type and with mixed cell type had a large percentage of intermediate stage (stage 2 and stage 3). A combination of pathologic grade and pathologic stage showed that patients with low grade had a higher incidence of low stage tumor than those with high grade. On the contrary patients with high grade had a higher incidence of high stage tumor than those with low grade. The significant correlation was observed between pathologic grade and pathologic stage.