Management of hyperplastic nephroblastomatosis

To the Editor:We read with great interest the important study on long-term survival of a large series of children with hyperplastic nephroblastomatosis (HN) recently reported by Perlman et al. [1]. Their findings support the conclusions of a previous report concerning our clinical experience in the management of HN and a review of the literature on this issue [2]. In our assessment, HN is not a rare lesion [2]. The main question is: Which management should be recommended to obtain the best ‘‘patient and kidney survival,’’ when HN is diagnosed on imaging? When the diagnosis of HN without WT was made before surgery, we started chemotherapy until disappearance of the lesion in an attempt to reduce the high risk of developing WT [2]. Actually, of the 23 collected cases with HN diagnosed by imaging or during the operation, 20 (86%) presented initially or subsequently with WT [2]. Similarly, Perlman et al. [1] found that all three patients with HN managed without adjuvant chemotherapy developed a WT. Conversely, of 33 patients managed with adjuvant chemotherapy, 18 (55%) developed a WT; furthermore, of 16 patients managed with adjuvant chemotherapy and nephrectomy, 3 (19%) developed a WT (P< 0.03) [1]. These data taken all together strongly support the concept that the reduction of the number of cells capable of malignant transformation reduces to a great extent the very high risk of developing WT. As children with HN might develop a WT in both kidneys, Beckwith [3] advised pre-operative chemotherapy and nephron-sparing surgery (NSS) for developing WT in children with HN. We first applied this concept in the management of two infants with HN, who developed a unilateral WT despite chemotherapy; and one infant with unilateral HN associated WT at presentation. In our patients with HN and WT, adjuvant chemotherapy associated with NSS did not impair survival and allowed maximum sparing of the parenchyma of both kidneys [2]. Perlman et al. reported that 14 of the 24 patients with HN, who developed WT, underwent NSS or excisional biopsy. Of these, 11 patients retained more than one kidney without evidence of disease at long-term follow-up; one disease-free patient required a nephrectomy for a recurrent WT; and two with diffuse anaplastic WT died of disease [1]. These data suggest that in children with HN and unilateral WT, NSS may be a reasonable alternative to nephrectomy in children with unilateral non-anaplastic WT and HN. The SIOP Study Group (SIOP 2001) advises adjuvant chemotherapy for the treatment of HN, and NSS for the treatment of WT associated with HN. We limited the indication of NSS for stage I non-anaplastic WT associated with HN [2]. This prudential approach seems appropriate considering that Perlman et al. [1] found that anaplasia is much more common in patients with HN and WT (32%) than in patients with sporadic WT (5%). In addition, the only two patients who died following NSS had a diffuse anaplastic WT [1]. We conclude that in children with HN, adjuvant chemotherapy is better than ‘‘wait and see’’ policy. In selected children with HN who developed WT, NSS may allow disease-free survival with two functioning kidneys. The conservative management has a renal function advantage over nephrectomy [4].