5-Minute Pediatric Consult
4th Edition

Abdominal Mass
Rose C. Graham-Maar
Chris A. Liacouras
Either an unusually enlarged abdominal or retroperitoneal organ (i.e., hepatomegaly, splenomegaly, or enlarged kidney) or a defined fullness in the abdominal cavity not directly associated with an abdominal organ.
Differential Diagnosis
  • Gastroparesis
  • Duplication
  • Foreign body/bezoar
  • Gastric torsion
  • Gastric tumor (lymphoma, sarcoma)
  • Infiltrative disease (Gaucher, Niemann-Pick)
  • Langerhans cell histiocytosis
  • Leukemia
  • Hematologic (hemolytic disease, sickle cell disease, hereditary spherocytosis/elliptocytosis)
  • Feces (constipation)
  • Meconium ileus
  • Duplication
  • Volvulus
  • Intussusception
  • Intestinal atresia or stenosis
  • Inflammatory bowel disease complications (abscess, phlegmon)
  • Appendiceal or Meckel diverticulum abscess
  • Toxic megacolon
  • Mesenteric/omental cyst
  • Mesenteric fibromatosis
  • Lymphoma, Adenocarcinoma
  • Carcinoid
  • Foreign body
  • Duodenal hematoma (trauma)
  • Pseudocyst (trauma)
  • Pancreatoblastoma
  • Endocrinologic (glycogen storage disease)
  • Infectious (hepatitis A, B, C)
  • Congenital hepatic fibrosis
  • Tumor (hepatic adenoma, hepatoblastoma, hepatocellular carcinoma)
  • Vascular (hamartoma, hemangioma, hemangioendothelioma)
  • Cystic disease (Caroli disease)
  • Focal nodular hyperplasia
  • Posterior urethral valves
  • Neurogenic bladder
  • Cysts (dermoid, follicular)
  • Torsion
  • Germ cell tumor
  • Hydronephrosis/ureteropelvic obstruction1
  • Polycystic/multicystic kidney disease1
  • Wilms tumor
  • Renal vein thrombosis
  • Mesoblastic nephromas
  • Ascites
  • Teratoma
  • Pregnancy
  • Hematocolpos
  • Hydrometrocolpos
  • Adrenal hemorrhage
  • Adrenal abscess
  • Neuroblastoma
  • Pheochromocytoma
  • Choledochal cyst
  • Hydrops
  • Obstruction (stone, stricture, trauma)
  • Umbilical/inguinal/ventral hernia
  • Omphalocele/gastroschisis
  • Trauma (rectus hematoma)
  • Tumor (fibroma, lipoma, rhabdomyosarcoma)
  • Lymphangioma
  • Fetus-in-fetu
Approach to the Patient
Abdominal masses in children are often found by an unsuspecting parent during bathing or by a physician during a routine physical examination. Most masses have no specific signs or symptoms. In children, abdominal masses require immediate attention. When evaluating a pediatric abdominal mass, an organized approach is paramount in determining its etiology.
  • Phase 1: Determine the location of the abdominal mass and its association with intraabdominal organs.
  • Phase 2: Perform diagnostic tests; the abdominal x-ray and ultrasound are the most efficient way to start the evaluation.
  • Phase 3: Treatment (see Laboratory Aids)
Data Gathering
Question: Weight loss?
Significance: Tumor, inflammatory bowel disease
Question: Fever?
Significance: Abscess, malignancy
Question: Jaundice?
Significance: Liver/biliary disease
Question: Hematuria or dysuria?
Significance: Renal disease
Question: Vomiting?
Significance: Intestinal obstruction
Question: Frequency and quality of bowel movements?
Significance: Constipation, intussusception, compression of bowel by mass
Question: Bleeding or bruising?
Significance: Coagulopathy
Question: History of abdominal trauma?
Significance: Pancreatic pseudocyst
Question: Sexual activity?
Significance: Pregnancy
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. In neonates, the most common origin of abdominal masses is the genitourinary system (cystic kidney disease, hydronephrosis). In infants and preschool-aged children, the most common malignant tumors are Wilms tumor and neuroblastoma. In adolescent-aged girls, ovarian disorders, hematocolpos, and pregnancy are more common causes of abdominal masses.

Physical Examination
  • Finding: General appearance
  • Significance: Ill-appearing or cachexia point toward infection or malignancy
  • Finding: Location of abdominal mass
  • Significance: Helps to narrow differential diagnosis
    • Left lower quadrant—Constipation, ovarian process, ectopic pregnancy
    • Left upper quadrant—Anomaly of the kidney or spleen (mass)
    • Right lower quadrant—abscess (inflammatory bowel disease), intestinal phlegmon, appendicitis, intussusception, ovarian process, ectopic pregnancy
    • Right upper quadrant—involves liver, gallbladder, biliary tree, or intestine
    • Epigastric—Abnormality of the stomach (bezoar, torsion), pancreas (pseudocyst), or enlarged liver
    • Suprapubic—Pregnancy, hydrometrocolpos, hematocolpos, posterior urethral valves
    • Flank—Renal disease (cystic kidney, hydronephrosis, Wilms tumor)
  • Finding: Characteristics of abdominal mass
  • Significance: Mobility, tenderness, firmness, smoothness, and/or irregularity of the surface of the mass can provide clues to its significance
  • Finding: Hard and immobile mass
  • Significance: Tumor
  • Finding: Extension of mass across midline or into pelvis
  • Significance: Tumor, hepatomegaly, splenomegaly
  • Finding: Percussion of mass
  • Significance: Dullness indicates a solid mass; tympany indicates a hollow viscus
  • Finding: Shifting dullness, fluid wave
  • Significance: Ascites
  • Finding: Skin examination
  • Significance: Bruising and petechiae may occur with coagulopathy related to liver disease and malignant infiltration of bone marrow; café au lait spots are associated with neurofibromas
  • Finding: Lymphadenopathy or lymphadenitis
  • Significance: More systemic process, either malignant or infectious
The abdomen of a normal infant and child should be completely soft and nontender. As a child ages, an increase in abdominal wall musculature may give greater resistance on examination, but the normal abdomen should continue to be soft to deep palpation. Palpation of an abdominal mass is abnormal and should be further evaluated.
Laboratory Aids
  • Test: CBC
  • Significance: Anemia or hemolysis
  • Test: Chemistry panel
  • Significance:
    • Renal disease (BUN, creatinine)
    • Liver disease (ALT, AST, alkaline phosphatase, albumin)
    • Gallbladder disease (bilirubin, GGT)
    • Pancreatic disease (amylase/lipase)
    • Intestinal disease (hypoalbuminemia)
  • Test: Uric acid, lactate dehydrogenase
  • Significance: Elevated in the setting of rapid cell turnover of solid tumors
  • Test: Plain abdominal x-ray studies
  • Significance: Rule out intestinal obstruction, identify calcifications, stool pattern
  • Test: Abdominal ultrasound
  • Significance: Can usually identify the origin of the mass and differentiate between solid and cystic tissue; disadvantages are operator variability and a limited exam when bowel gas obscures underlying abdominal tissues
  • Test: Computed tomography (CT) scan
  • Significance: Can provide more detail when there is overlying gas or bone; if malignancy is suspected should do chest, abdomen, and pelvis CT
  • Test: Magnetic resonance imaging
  • Significance: Vascular lesions of liver, major vessels, and tumors
  • Test: Radioisotope HIDA scan
  • Significance: Liver, gallbladder
  • Test: Intravenous urography or voiding cystourethrography
  • Significance: Wilms tumor, cystic kidney disease, posterior urethral valves
  • Test: Upper gastrointestinal (GI), barium enema
  • Significance: May be of benefit when the mass involves the intestine
  • Test: Endoscopy
  • 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
Emergency Care
  • 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
  • Ectopic pregnancy
  • Biliary obstruction (stone, hydrops)
  • Fever
  • Pancreatitis (pseudocyst) requires immediate hospitalization.
Initial diagnostic studies should include plain abdominal x-ray studies, an abdominal ultrasound, and a surgical consultation. The remaining causes of abdominal masses require urgent care and timely evaluation.
Except for the diagnosis of constipation, the presence of an abdominal mass requires immediate attention and diagnostic studies should be performed expeditiously at a facility capable of diagnosing pediatric disorders.
  • In neonates, a palpable liver edge can be normal; the total liver span is most important
  • In infants, a full bladder is often mistaken for an abdominal mass.
  • In infants, most abdominal masses are of renal origin and nonmalignant.
  • Severe constipation in older children and adolescents can present as a large, hard mass extending from the pubis past the umbilicus.
  • Gastric distension should be considered in all children who present with a tympanitic epigastric mass.
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1Most common in newborns