Solitary renal hamartoma not associated with tuberous sclerosis: roles of CT and angiography.

CT and angiography of five solitary renal hamartomas not associated with tuberous sclerosis are reviewed. CT revealed fat in four hamartomas and was the more reliable in the differentiation from renal cancer. Bleeding from the tumour was detected in two cases and the extent of each haematoma was precisely determined by CT. Angiography showed specific findings in only one tumour. In a pararenal hamartoma, angiography was of value in clarifying the renal origin of the tumour. Though angiography may be of help when CT is inconclusive, we think it should not be relied upon as a major diagnostic tool and we utilise it mainly for preoperative mapping and embolisation. In one case CT did not detect fat and preoperative diagnosis was impossible. In one case with haematoma, detection of fat was difficult. We believe potential hamartomas with no detectable fat should be treated as malignancy until proved otherwise. There seems to be discrepancy between the vascularity of the hamartoma and the degree of contrast enhancement (CE) with a bolus injection method; hamartomas seem to show weaker CE than that expected for renal cancer of equal vascularity, a fact which may differentiate solitary hamartoma from cancer.