What Is the Differential Diagnosis for This Child’s Abdominal Mass?

Malignancy is a serious concern with a new pediatric abdominal mass. Pediatric abdominal malignancies to consider include neuroblastoma, Wilms tumor (nephroblastoma), lymphoma, rhabdomyosarcoma, renal cell carcinoma, leiomyosarcoma, teratoma, and germ cell tumors. Other organ pathologies that may manifest as an abdominal mass include polycystic kidney disease, Meckel’s diverticulum, and hepatic storage diseases. In a neonate one should also consider pyloric stenosis.

What Are the Clinical Characteristics of Neuroblastoma and Wilms Tumors?

Neuroblastoma is the most common extracranial pediatric tumor overall (with 65% of abdominal or adrenal origin), while Wilms tumor is the most common abdominal tumor in children. Both commonly present as palpable, painless abdominal masses without associated symptoms. Neuroblastomas may have associated hypertension, abdominal pain, constipation, or distension, while Wilms tumor often presents with hematuria and hypertension.

Children with localized disease may be asymptomatic other than a palpable mass, whereas those with advanced disease may appear cachectic and have constitutional symptoms (fever, weight loss). Large abdominal tumors may present with mass effect symptoms such as abdominal pain, fullness, bowel obstruction, or lower extremity edema. Mediastinal neuroblastoma can cause all of the most perilous symptoms of mediastinal masses including dyspnea from compression of the trachea or great vessels. Thoracic or cervical tumors may compress the sympathetic trunk causing Horner’s syndrome, while larger thoracic tumors may cause superior vena cava syndrome. Metastatic disease can occur in the liver, bone, and skin.

What Is Neuroblastoma?

Neuroblastoma is a malignancy of the primordial neural crest cells that give rise to the sympathetic chains and adrenal glands. Their origin can stem from any part of the sympathetic nervous system, namely the adrenal glands and sympathetic chains of the abdomen, thorax, pelvis, and cervical area. As they are derived of neural crest they are capable of catecholamine secretion, although unlike pheochromocytoma they do not typically present primarily with symptoms of hypertension.

What Is the Incidence and Epidemiology of Neuroblastoma?

There are about 700 new cases of neuroblastoma annually in the United States. They account for around 10% of pediatric malignancies, though they are responsible for approximately 15% of pediatric cancer-related deaths. Most children are diagnosed before the age of 4, with a median age at diagnosis of 19 months.