RENAL ADENOMA - IDENTIFICATION OF 2 HISTOLOGIC TYPES

In this paper the morphologic characteristics of renal adenoma are stu died in 4 groups of kidneys from 500 unselected autopsies performed fo r legal reasons, 5,000 autopsies from the files of a general hospital, 16 kidneys with adenoma and without carcinoma, and 200 kidneys with c arcinoma. All the tumors were classified by pattern, cytology and scle rosis of the renal nontumoral stroma. The relationship between tumor s ize, tumor histological type and sclerosis was evaluated by statistica l analysis. The differences in frequency were significant between the parameters size and histological type (p < 0.003), namely for solitary adenomas (p < 0.001). The differences in histological type observed i n multiple adenomas were not significant (p > 0.05). The differences w ere significant between the extent of sclerosis and histological type (p < 0.002) and tumor size (p < 0.009). This study identifies two dist inct groups of adenomas according to size, histological type and exten t of sclerosis, and suggests that small adenomas of the mixed tubulopa pillary type and with basophilic cells have little or no malignant pot ential. Conversely, adenomas with a solid or papillary pattern and cle ar cells are potentially malignant.