Pediatric Tumors

Diagnosis and therapy of pediatric tumors have a very long and productive history, and we feel indebted toward those pioneers who first opened the way to the understanding of the pathways that underlie the basic mechanisms of these special tumor types. The diagnosis of pediatric malignant tumors is often challenging.1–3 Accordingly, over the last two decades, there has been an increasing interest worldwide about the identification of tumor markers useful for both diagnostic and therapeutic purposes in pediatric oncology.4–14 Apart from neuroblastoma, hepatoblastoma, and germ cell tumors, the majority of solid pediatric tumors have no tumor-specific markers detectable in the serum of patients. In the present special issue, our aim is to provide original and review articles dealing with some pediatric tumors, emphasizing clinical, biochemical, and pathological features, which can be exploited by pediatricians, regardless of their subspecialties, in their daily practice. The need for a multidisciplinary approach, particularly with the joint effort of clinical and laboratory counterparts, is evident throughout the articles presented herein. This special issue begins with an overview on adrenocortical tumors in childhood. These neoplasms are relatively rare in pediatric age and their diagnosis (benign vs. malignant) is still challenging.15 In this regard, the article by Salvatorelli et al discusses the clinical, laboratory, and pathologic features useful in daily practice for achieving an accurate diagnosis. The article by Tumino et al summarizes the current understanding on bonemarrow transplantation for both malignant and nonmalignant hemopathies. They report some new interesting acquisitions about the allogeneic transplant with a haploidentical, semi-compatible, donor.16 The article by Ruggeri et al focuses on the pathophysiology of merlin structure and function, on its posttranslational and upstream/downstream regulation in the different forms of NF2 in the pediatric age.17 Neuroblastoma is one of the most frequent solid tumors in children. About half of the cases are metastatic, and its prognosis today still remains unfavorable despitemany new therapeutical approaches. The articles by Marino et al and Balaguer et al deal with typical biomarkers of neuroblastoma: the former focuses mainly on vanillylmandelic and homovanillic acids,18whereas the latter on metaiodobenzylguanidine (MIBG), a molecule that can be marked with radioactive 123or 131-iodine; due to the ability of neuroblastoma to uptake MIBG, this marker turns out to be extremely useful for diagnosis, follow-up, and treatment.19 Acute lymphoblastic leukemia is the most frequent childhood neoplasm, and its prognosis in the last two decades has become very good for most patients. Bonaccorso and colleagues discuss about the pathways involved in the leukemogenic process, and the prospective of a tailored treatment according to single specific profile, to further increase the efficacy with less toxicity.20 Extracranial malignant germ cell tumors have a favorable prognosis in children, with more than 80% survival rate. Yolk sac tumor is the histotype producing alfa-fetoprotein. Moscheo et al, in their article, discuss the role of thismarker at diagnosis and in the follow-up, as well as a prognostic factor.21 La Spina et al review the state of art of tumoral lysis syndrome by providing a comprehensive overviewof a complication that can occur in all pediatric neoplasms. The early recognition and, preferably, the prevention of tumoral lysis syndrome may have a huge impact on clinical practice.22 Bone sarcomas in childhood, if treatedwith a multidisciplinary approach including orthopedics and oncologists, present good results in terms of outcome for localized cases, while patients with metastatic disease are