Review of Paraneoplastic Syndromes in Children with Malignancy.

A paraneoplastic syndrome (PNS) is a set of symptoms and signs that can accompany the formation of a cancer but is not due to its direct infiltration or metastasis. PNS results from the secretion of peptides or hormones by tumor cells or from an immunological cross-reaction between the tumor antigens and host antigens. In the adult population, PNS affects up to 15% of patients with cancer, but data on pediatric patients remain lacking. The remarkable fact is that PNS can precede an oncology diagnosis, even by months or years. PNS can involve virtually any organ of the human body. In children, the most commonly involved are the nervous system (encephalitis, opsoclonus-myoclonus syndrome), skin (pemphigus, alopecia areata, pruritic skin, pyoderma gangrenosum, skin nevi), rheumatologic (dermatomyositis, vasculitis), liver (atrophic biliary syndrome, idiopathic cholestasis), endocrine system (hypercalcemia, syndrome of inadequate secretion of antidiuretic hormone), kidney (nephrotic syndrome), or hematopoietic system (hemolytic anemia, thrombocytopenia, eosinophilia, thrombotic macroangiopathy, leukomoid reaction). PNS can accompany all childhood cancers, but is most common in Hodgkin lymphoma, acute lymphoblastic and myeloid leukemia, neuroblastoma, Wilms tumor, and sarcoma. Diagnosis of PNS should begin as early as the suspicion of its unusual course, lack of response to standard treatment, or prolonged duration. Diagnosis should include typical disease-specific tests and simultaneous imaging of the head and neck, abdomen, and pelvis, as well as a bone marrow biopsy to look for malignancy. PNS treatment mainly includes anti-tumor therapy and sometimes additional immunosuppressive therapy. This article aims to review PNS in children with malignancy.