BONE METASTASIZING RENAL TUMOR OF CHILDHOOD

Eleven patients with bone metastasizing renal tumor of childhood (BMRT Ch) who were diagnosed and treated in our departments over a 20-year p eriod were reviewed. The incidence among all malignant renal tumors in children up to 15 years of age in our files was 3.7%. The male to fem ale ratio was 10.1. The morphology had a uniform, predominantly clear cell finely vascularized pattern in all of them. Various previously re cognized variations of the classic pattern such as hyalinization, nucl ear palisading and cyst formation were observed in some patients. Elec tron microscopy showed that coarse vacuolization of the tumor seen at the light microscopic level was due to distended extracellular spaces surrounded by tumor cells and their cytoplasmic processes. Immunohisto chemistry of the tumor cells revealed positive vimentin in all cases, and focally positive muscle specific actin in one. A prominent feature was fascicles of perivascular spindle cells. They were considered to be tumor cells rather than stomal elements since their morphology was close to the appearance of the polygonal tumor cells. The follow up da ta were available for ten patients. Another patient died of lymph node dissemination and gastrointestinal bleeding. Six patients survived fo r a period of 29 months to 14 years following the diagnosis.