Kidney, Adrenal Gland, and Retroperitoneum

The kidney, adrenal gland, and retroperitoneum are important sites of disease in the pediatric population. Some of the most frequently encountered childhood neoplasms, including Wilms tumor and neuroblastoma, arise in the kidney and adrenal gland, respectively. Many of these tumors are deep-seated but amenable to fine-needle aspiration (FNA). Children with a renal, adrenal, or retroperitoneal malignancy may present at an advanced stage and be too ill to withstand the rigors of surgery. Thus, neoadjuvant chemotherapy may be used to debulk some of these tumors before surgery is performed, and an accurate cytologic diagnosis is imperative to ensure the appropriate management is undertaken. This chapter covers both common and more unusual lesions that may be encountered when looking at an FNA from this area. In addition, urine cytology in children is discussed briefly.