Description

A palpable lesion or fullness in the abdominal cavity which may or may not be related to abdominal viscera or a lesion detected on abdominal imaging; the mass may be abdominal or retroperitoneal in origin.

Epidemiology

• Etiologies for abdominal masses are varied, and the differential depends on age and anatomic location.
• Majority are nonsurgical in nature; may be associated with constipation
• Approximately 57% of abdominal masses in children are due to organomegaly (hepatomegaly or splenomegaly).
• Most abdominal masses in infants originate from the kidney and are benign (e.g., hydronephrosis); Wilms tumor is the most common malignant tumor of the kidney seen in childhood.
• Liver masses account for 5–6% of all pediatric intra-abdominal masses; hepatoblastoma is the most common primary liver tumor in children, often presenting at 1 to 3 years of age.

Risk Factors

• Certain genetic disorders/syndromes are associated with increased risk of tumor development.
• Patients with Beckwith-Wiedemann syndrome; Wilms tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR); and Denys-Drash syndrome are at increased risk of Wilms tumor and require regular screening.

General Prevention

Dependent on whether or not the mass or lesion is related to a modifiable factor (e.g., a retained foreign body requires parental or patient counseling for prevention)

Pathophysiology

Varies based on the type of mass seen

Etiology

• Stomach
  • Gastric distension or gastroparesis
  • Duplication
  • Foreign body or bezoar
  • Gastric torsion
  • Gastric tumor (lymphoma, sarcoma)
• Intestine
  • Feces (constipation)
  • Intestinal distension or toxic megacolon
  • Foreign body
  • Meconium ileus
  • Duplication
  • Volvulus
  • Intussusception
  • Intestinal atresia or stenosis
  • Malrotation
  • Complications of inflammatory bowel disease (abscess, phlegmon)
  • Appendiceal inflammation
  • Meckel diverticulum or abscess
  • Duodenal hematoma (trauma)
  • Lymphoma, adenocarcinoma, GI stromal tumor
  • Carcinoid (appendiceal)
• Liver
  • Hepatomegaly due to intrinsic liver disease
    • Hepatitis (e.g., infectious, autoimmune)
    • Metabolic or storage disorders (e.g., Wilson disease, glycogen storage disease)
    • Infiltration of liver (cyst, tumors)
    • Biliary obstruction
    • Vascular obstruction/impaired venous congestion (Budd-Chiari syndrome, congestive heart failure)
  • Cystic disease (e.g., Caroli disease)
  • Solid tumor (hepatoblastoma; hepatocellular carcinoma; hepatic adenoma; or other diffuse, systemic, neoplastic process)
  • Vascular tumor (hemangioma or hemangioendothelioma)
  • Other: hamartomas, focal nodular hyperplasia
• Gallbladder/biliary tract
  • Choledochal cyst
  • Hydrops of gallbladder
  • Obstruction (stone, stricture, trauma)
• Spleen
  • Congenital cysts
  • Storage disease (e.g., Gaucher, Niemann-Pick)
  • Langerhans cell histiocytosis
  • Leukemia
  • Hematologic (hemolytic disease [e.g., sickle cell] or other RBC disorders [e.g., hereditary spherocytosis])
  • Portal hypertension
  • Wandering spleen
• Pancreas
  • Congenital cysts
  • Pseudocyst (trauma, pancreatitis)
  • Pancreatoblastoma
  • Neuroendocrine tumors (insulinomas, gastrinomas)
  • Solid and papillary epithelial neoplasms
• Kidney
  • Hydronephrosis or ureteropelvic obstruction
  • Multicystic dysplastic kidney
  • Polycystic disease
  • Tumor (mesoblastic nephroma, Wilms tumor, renal cell carcinoma)
  • Renal vein thrombosis
  • Cystic nephroma
• Bladder
  • Bladder distension
  • Neurogenic bladder
• Adrenal
  • Adrenal hemorrhage
  • Adrenal abscess
  • Neuroblastoma
  • Pheochromocytoma
• Uterus
  • Pregnancy
  • Hematocolpos
  • Hydrocolpos or hydrometrocolpos
• Ovary
  • Cysts (dermoid, follicular)
  • Torsion
  • Germ cell tumor
• Peritoneal
  • Ascites
  • Teratoma
• Abdominal wall
  • Umbilical/inguinal/ventral hernia
  • Omphalocele/gastroschisis
  • Urachal cyst
  • Trauma (rectus hematoma)
  • Tumor (fibroma, lipoma, rhabdomyosarcoma)
• Omentum/mesentery
  • Cysts
  • Mesenteric fibromatosis
  • Mesenteric adenitis
• Other
  • Tumors (liposarcoma, leiomyosarcoma, fibrosarcoma, mesothelioma)
  • Intra-abdominal testicle (torsion)
  • Lymphangioma
  • Fetus in fetu
  • Sacrococcygeal teratoma