Pathology of selected abdominal masses in children

Abstract

EUROBLASTOMA is the most common neoplasm that causes abdominal enlargement in childhood. The adrenal medulla and the retroperitoneal sympathetic nerves are the principal primary sites. Long-established favorable prognostic factors in patients with neuroblastoma are diagnosis during infancy, clinical stage, thoracic location, and high degree of maturation in the primary tumor? Presumably all ganglioneuromas originate as neuroblastoma, and it is reasonable to think that the rapidity and extent of maturation is an important prognostic feature. Serum levels of ferritin, neuron-specific enolase, and E-rosette inhibition have all been reported to distinguish patients at high risk from those at low risk. ~ The amplification of the oncogene N-myc has been correlated with advanced stages of neuroblastoma and promises to be an excellent predictor of outcome) The broad spectrum of clinical behavior and stubborn resistance of many neuroblastomas to modern therapy has encouraged studies aimed at refining histologic criteria so as to improve prediction of outcome. The recent excellent effort by Shimada et al I has produced a scheme wherein the lesion is classified as stroma-poor (80% of cases) or stroma-rich (20% of cases) on the basis of neuritic (partially mature) or neuromatous (mature) stroma content. The stroma-poor group is further classified as favorable (84% survival) and unfavorable (4.5% survival) on the basis of age at diagnosis, degree of maturation, and frequency of mitosis/karyorhexis. The prospect that this approach may identify younger patients with aggressive tumors and older patients with less aggressive tumors is encouraging. The stromarich group is further classified into well-differentiated (100% survival), mixed (92% survival), and nodular (18% survival). Well-differentiated tumors are essentially ganglioneuromas with nearly complete maturation. The mixed and nodular lesions are composed of both neuroblastoma and ganglioneuroma tissue, and have been termed composite neuroblastoma. 4 The ominous nodular form consists of a discrete mass of neuroblastoma surrounded by mature ganglioneuroma tissue (Fig 1). Nodular composite tumors may represent emergence of a clone of mutant malignant neuroblasts at a late stage in the orderly sequence of ganglioneuromotous maturation. Careful attention to surgical, radiologic, and pathologic technique is necessary to identify nodular stroma-rich composite neuroblastoma. RENAL MASSES