• Gastroparesis
• Duplication
• Foreign body/bezoar
• Gastric torsion

• Infiltrative disease (Gaucher, Niemann-Pick)
• Histiocytosis X
• Leukemia
• Hematologic (hemolytic disease, sickle cell disease, hereditary spherocytosis/elliptocytosis)

• Feces (constipation)
• Duplication
• Volvulus
• Intussusception
• Inflammatory bowel disease complications (abscess, phlegmon)
• Toxic megacolon
• Mesenteric/omental cyst
• Lymphoma
• Foreign body
• Appendiceal abscess

• Pseudocyst (trauma)

• Endocrinologic (glycogen storage disease)
• Infectious (hepatitis A, B, C)
• Congenital hepatic fibrosis
• Tumor (neuroblastoma, Wilms, leukemia)
• Vascular (hemangioma, hemangioendothelioma)

• Urethral valves
• Neurogenic bladder

• Dermoid
• Follicular cyst
• Torsion
• Gonadal tumor

• Hydronephrosis/ureteropelvic obstruction
• Polycystic/multicystic disease¹
• Wilms tumor
• Renal vein thrombosis
• Nephroblastomatosis

• Ascites
• Teratoma

• Pregnancy
• Hydrometrocolpos

• Neuroblastoma
• Adrenal hemorrhage
• Pheochromocytoma

• Choledochal cyst
• Hydrops
• Obstruction (stone, stricture, trauma)

• Umbilical/inguinal/ventral hernia
• Omphalocele/gastroschisis
• Trauma (rectus hematoma)
• Tumor (fibroma, lipoma, rhabdomyosarcoma)

• Mesenteric cyst
• Omental cyst
• Lymphangioma

Question: Frequency and quality of bowel movements?
Significance: Constipation, intussusception

Question: History of abdominal trauma?
Significance: Pancreatic pseudocyst

Question: History of weight loss?
Significance: Tumor, posterior urethral valves, inflammatory bowel disease

Question: Presence of jaundice?
Significance: Liver/biliary disease

Question: Hematuria or dysuria?
Significance: Renal disease

Question: Sexual activity?
Significance: Pregnancy

Question: Fever?
Significance: Abscess

Question: What is the age of the patient?
Significance: The age of the patient is often a helpful clue in investigating the cause of the abdominal mass. The most common types of abdominal mass in newborns include renal disease (cystic kidney disease, renal vein thrombosis, hydronephrosis), adrenal hemorrhage, congenital anomalies, and teratoma. In preschool-aged children and adolescents, approximately 20% of abdominal masses arise from the gastrointestinal tract, while 5% have their origin in the liver or biliary tree. Wilms tumor typically occurs in preschool-aged children, while ovarian disorders present in adolescents.

Finding: Location of the mass
Significance:

Finding: Epigastric mass
Significance: Commonly arises from an abnormality of the stomach (bezoar, torsion) or the pancreas (pseudocyst)

Finding: Flank masses
Significance: Often represent renal disease

Finding: Hard and immobile
Significance: Palpable tumors

Finding: Large, extends across the midline
Significance: Teratomas

The abdomen of a normal infant and child should be completely soft and non-tender. As a child ages, an increase in abdominal wall musculature may give greater resistance on examination, but the abdomen should continue to be soft to deep palpation.

Test: CBC
Significance: Anemia or hemolysis

Test: Chemistry panel
Significance: Renal disease (BUN, creatinine), liver disease (ALT, AST, alkaline phosphatase), gallbladder disease (bilirubin, GGTP), pancreatic disease (amylase), or intestinal disease (hypoalbuminemia)

Test: Abdominal ultrasound
Significance: Most useful pediatric diagnostic test for the evaluation of abdominal masses because the paucity of fat in children enhances its diagnostic detail; the disadvantage of ultrasound is its operator variability and its limitations when bowel gas obscures underlying abdominal tissues.

Test: Computed tomography scan
Significance: Can provide more detail when there is overlying gas or bone

Test: Plain abdominal x-ray studies
Significance: Presence of calcifications, extension into the chest

Test: Magnetic resonance imaging
Significance: Vascular lesions of liver, major vessels, and tumors

Test: Radioisotope HIDA scan
Significance: Liver, gallbladder, and intravenous urography (Wilms tumor, cystic kidney disease)

Test: Upper gastrointestinal, barium enema
Significance: Can be of benefit when the mass involves the intestine

Test: Laparoscopy
Significance: Can be useful for direct intraperitoneal visualization and biopsy of abdominal masses

Of all the diseases listed in the differential diagnosis, patients who present with an abdominal mass and signs and/or symptoms of intestinal obstruction (intussusception, volvulus, gastric torsion, bezoar, foreign body), toxic megacolon, ovarian torsion, biliary obstruction (stone, hydrops), fever, or pancreatitis (pseudocyst) require immediate hospitalization. Initial diagnostic studies should include an abdominal ultrasound, plain abdominal x-ray studies, and a surgical consultation. The remaining causes of abdominal masses require urgent care and timely evaluation.

Issues for Referral

Except for the diagnosis of constipation, the presence of an abdominal mass requires immediate attention. For all masses in children, diagnostic studies should be performed expeditiously at a facility capable of diagnosing pediatric disorders. Once the abnormality is identified, the appropriate pediatric subspecialist should be consulted.

Clinical Pearls

In infants, a full bladder is often mistaken for an abdominal mass, while in neonates, a palpable liver edge can be normal and is often appreciated. Severe constipation in older children and adolescents can present as a large, hard mass extending from the pubis past the umbilicus. Finally, gastric distention should be considered in all children who present with a tympanitic epigastric mass.

Mahaffey SM, Rychman RC, Martin LW. Clinical aspects of abdominal masses in children. Semin Roentgenol 1988;23:161–174.

Merten DF, Kirks DR. Diagnostic imaging of pediatric abdominal masses. Pediatr Clin North Am 1985;32:1397–1426.

Schwartz MW. Abdominal masses. In: Schwartz MW, Curry TA, Charney ED, Ludwig S, eds. Principle and practice of clinical pediatrics. Chicago: Yearbook, 1987, 139–144.

Swischuk LE, Hayden CK Jr. Abdominal masses in children. Pediatr Clin North Am 1985;32:1281–1298.

Taylor LA, Ross AJ III. Abdominal masses. In: Walker WA, Durie PR, Hamilton JR, Walker-Smith JA, Watkins JB, eds. Pediatric gastrointestinal disease. Philadelphia: BC Decker, 1991, 132–146.