Primary renal neuroblastoma--a clinical pathologic study of 8 cases.

Neuroblastoma is the most common extracranial solid tumor to occur during infancy and early childhood. However, primary renal neuroblastoma is rare, and only scattered case reports exist in the English medical literature. We report 8 cases that accumulated at our institution over the past 15 years and summarize their clinicopathologic features. The composite picture of a patient with renal neuroblastoma is that of a boy of 17 months of age, who presented with a large renal mass, about 9 cm in size, accompanied by hypertension. The mass was typically hemorrhagic, either encapsulated or unencapsuated, and infiltrating. A renal neuroblastoma can be undifferentiated, poorly differentiated, or differentiating; it falls into either the favorable or the unfavorable histology category, and presentation at higher stages is the rule. The N-myc is usually unamplified, and the bone marrow is usually not involved at presentation. Unless the tumor is undifferentiated or very poorly differentiated, patients with renal neuroblastoma fare well, although not without new and improved modalities of treatment. Primary renal neuroblastoma is perhaps more common than people realize; a higher level of awareness and early recognition are important for its prognosis and management, as they are very different from Wilms tumor.