[Preoperative factors of misdiagnosis of renal angiomyolipoma].

Objectives: To explain the high incidence of misdiagnosis of angiomyolipoma (AML) prior to surgery.

Materials And Methods: Between 1989 and 2007, 2,657 patients were operated for a renal tumor at Dupuytren hospital in Limoges and at Cochin hospital in Paris. In 85 cases (3.2%), tumors were AMLs on pathology. The group of patients in which the diagnosis was done preoperatively was compared to the one in which the diagnosis was missed.

Results: Mean age of patients was 57-years-old and the sex-ratio was five women for one man. The mean size of AMLs was 5.4 cm. The patients were symptomatic in 46% of cases (39/85). The diagnosis of AML was ignored preoperatively in 62 patients (73%). In multivariate analysis, the small size of the AML, low proportion of fat and male sex were significantly associated with misdiagnosis of AML (p<0.001, p<0.018 and p<0.008, respectively).

Conclusions: The incidence of misdiagnosis of AML preoperatively is high. The diagnosis seems particularly difficult when the tumor is small or contains a small proportion of fat. In addition, this study highlights that the diagnosis of AML is frequently ignored in men. The increased resolution of CTscan and the use of preoperative biopsies for tumors less than 4 cm could be helpful to decrease the incidence of useless surgery of AMLs.