The most common malignant SOLID tumor of childhood is neuroblastoma, developing from neoplastic transformation of neural-crest derived cells. While leukemia and lymphoma are common pediatric cancers, they are not "solid" tumors. Eosinophilic granuloma is not a malignant tumor but rather described as a tumor like condition secondary to an increase in histiocytes. While Ewing's sarcoma is a common solid neoplasm, it is not as common as neuroblastoma.
Dormans and Moroz review the diagnosis, management, and outcomes of spinal tumors and infections in children. While neuroblastoma is derived from neural crest cells, it most frequently originates in one of the adrenal glands, neck, chest, abdomen, or pelvis.
Illustration A shows a large mass growing in the area of the right kidney which was biopsy proven to be neuroblastoma. Note how large the pediatric liver is in relation to the rest of the abdominal cavity. Illustration B is a histology slide of a neuroblastoma with its characteristic small round blue cells (like Ewing's sarcoma) with rosette formation.
Khanna G, El-Khoury GY, Menda Y. Imaging in pediatric orthopaedics. In: Morrissy RT, Weinstein SL, eds. Lovell and Winter's Pediatric Orthopaedics. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006:67-96.
Dormans JP, Moroz L. Infection and tumors of the spine in children. J Bone Joint Surg Am. 2007 Feb;89 Suppl 1:79-97. Review.
PMID:17272426 (Link to Abstract)