Malignancy	Frequency (%)2,3	Main clinical characteristics4–6
Leukemia (acute lymphoblastic leukemia; acute myelogenous leukemia)	34.1	Pallor, fatigue, prolonged fever with no identifiable cause, persistent or recurrent infections, anorexia, petechiae, bruising or gingival bleeding, lymphadenopathy, hepatosplenomegaly, bone pain (generalized or involving the joints) or limp, irritability, neurologic symptoms
Central nervous system tumors (brain, cranial nerves, spinal cord)	22.6	Persistent headache (mainly in the morning), nausea and vomiting, ataxia, visual disturbances (diplopia, squint, papilledema, proptosis), neurologic defecits (cranial nerve palsies, motor and sensory signs), seizures, developmental delay or regression, unexplained deteriorating school performance, personality changes, torticollis, signs of raised intracranial pressure (increasing head circumference, bulging fontanelle, irritability)
Lymphoma (Hodgkin, non-Hodgkin)	11.5	Lymphadenopathy, fever or “B symptoms” (night sweats, fever, weight loss), pallor, fatigue, petechiae or bruising, abdominal mass, hepatosplenomegaly, nausea and vomiting, constipation, abdominal pain
Neuroblastoma	7.6	Palpable mass (abdomen, neck), anorexia and failure to thrive, fever, bone pain, lymphadenopathy, pallor, malaise, irritability, leg weakness, ocular symptoms (periorbital ecchymoses, proptosis, squint, opsoclonus-myoclonus syndrome, heterochromia of the iris, Horner syndrome), back pain, subcutaneous nodules, obstructive symptoms of the bowel and bladder, neurologic defecits
Soft tissue sarcomas (mainly rhabdomyosarcoma)	6.1	Palpable mass, symptoms caused by pressure on adjacent structures, lymphadenopathy (depending on location of tumor), squint or proptosis (orbital location), vaginal bleeding (vaginal location)
Renal tumors (mainly Wilms tumor)	5.6	Abdominal mass, abdominal pain, hematuria, vomiting, constipation, fever, hypertension
Germ cell tumors	3.1	Palpable mass (scrotum), respiratory symptoms (mediastinal location), abdominal distension and pain (abdominal location), constipation, enuresis, precocious puberty or amenorrhea, vaginal bleeding, leg weakness, neurologic symptoms (central nervous system location)
Osteosarcoma	2.3	Localized bone pain, palpable mass, swelling or deformity, pathological fracture
Ewing sarcoma	2.1	Localized bone pain, palpable mass (depending on location), prolonged fever, fatigue, weight loss, compression of local structures (bladder, spinal cord), symptoms due to bone marrow infiltration
Retinoblastoma	2.1	Leukokoria (cat's eye reflex), squinting, vision loss
Hepatic tumors	1.1	Abdominal distention or mass, symptoms depend on type of tumor
Histiocytosis	< 0.5	Bone pain (localized or generalized), rashes (eczema resistant to treatment), fever, weight loss, lymphadenopathy, hepatosplenomegaly, chronic ear discharge or otitis media, proptosis, diabetes insipidus
Nasopharyngeal carcinoma	< 0.5	Cervical lymphadenopathy, persistent nasal obstruction, epistaxis, persistent otitis media, tinnitus, headache, fever, trismus, dysphagia, cranial nerve palsies
Others	< 1	Clinical characteristics depend on location and histology (various malignant epithelial carcinomas [e.g., thyroid, lung, breast, bladder, skin], melanomas, or unspecified neoplasms)