The applicability of Ki-67 marker for renal epithelioid angiomyolipoma: experience of ten cases from a single center.

In order to present our experience with 10 cases of renal epithelioid angiomyolipoma (EAML) and validate the applicability of Ki-67 (proliferation marker) for EAML, we reviewed medical records of 10 consecutive cases diagnosed EAML from January 2005 to February 2012 at our department. Clinical data were collected and analyzed and pathology slides were reviewed. The immunohistochemical reactions for Ki-67 were performed and tumors showed positive expression were estimated. Active follow-up was performed to investigate the association between Ki-67 expression and the prognosis. The mean age and tumor size of the patients was 43.6 years (range 32-56) and 8.2 cm (range 2-15 cm), respectively. Seven were females while three were males. Radical nephrectomy was performed in 6 patients, partial nephrectomy in 3, and renal artery ligation in 1. The immunohistochemical reactions for HMB-45 (Human Melanoma Black), SMA (Smooth Muscle Actin) were positive but for S-100 were negative. The number of patients showing positive/negative Ki-67 expression was 5/5. The survival rate of the positive group was 20% (1/5) while 100% (5/5) of the negative group during the median follow-up time of 26.75 months (range 1-53). Recurrence, metastasis and death due to disease occurred in 1 (10%), 3 (30%) and 4 (40%) patients, respectively. Higher expression (positive) of Ki-67 indicates the presence of EAML and poor prognosis of patients. Surgical excision including radical and partial nephrectomy is a considerable approach to the treatment for its malignant potential.