132: Surgical Diseases of the Newborn: Abdominal Masses

Gastrointestinal masses are palpable abdominal masses that arise from the gastrointestinal tract are unusual and tend to be cystic, smooth walled, and mobile (depending on size). Causes include intestinal duplications and mesenteric cyst. Malignancy is rare.

Hepatomegaly results from a variety of conditions. When physical examination and ultrasonography suggest a discrete mass, magnetic resonance imaging (MRI) or computed tomography (CT) should be performed. These studies are often diagnostic and aid in surgical planning. Lesions include the following:

Congenital, solitary, nonparasitic liver cysts are rare in newborns

1. Hamartomas commonly have a cystic component. They are characterized by fine internal septations without calcifications. Surgical removal and cyst marsupialization are options.

2. Hemangioendotheliomas are the most common benign, solid hepatic tumors in children. They are often asymptomatic, but may present with high output heart failure, anemia, thrombocytopenia, and coagulopathy (Kasabach-Merritt syndrome). Hepatic transaminases and α-fetoprotein are usually normal. Diagnosis can be made by contrast CT scan or MRI. Typically, lesions begin to regress at ∼1 year of age. Treatment is reserved for symptomatic lesions. Options include interferon, systemic corticosteroids, or vincristine. Surgical resection, embolization, and liver transplantation have been described for select lesions.

Hepatoblastoma is the most common liver cancer in neonates. Serum α-fetoprotein is usually elevated. Although surgical resection remains the key to achieving a cure, new chemotherapeutic protocols (cisplatin and doxorubicin) have improved the formerly dismal prognosis for infants with this tumor. Hepatic transplantation for unresectable lesions is associated with improved outcomes.

A simple ovarian cyst is a frequent cause of a palpable abdominal mass in the female neonate. It presents as a relatively mobile, smooth-walled abdominal mass. It is not associated with cancer, and excision with preservation of any ovarian tissue is curative. Smaller lesions (≤5 cm) may be followed with serial ultrasounds over the first year of life as long as they regress. Larger lesions may benefit from percutaneous aspiration to decrease risk of ovarian torsion.

(See also Chapters 136 and 137.) In most clinical series, the majority of neonatal abdominal masses arise from the kidney. They may be unilateral or bilateral, solid or cystic. After physical examination, ultrasonography should be obtained to define whether the mass is solid or cystic, to determine the presence or absence of normal kidneys, and to assess for other intra-abdominal abnormalities. In selected instances, additional procedures such as renal scan, CT, retrograde pyelography, venography, and arteriography may be needed to define the pathology and plan appropriate therapy.

Most common renal cystic disease of the newborn. It is usually unilateral. Ultrasonography can define the nature of the disorder, and CT/nuclear renal scans are useful in assessing the remainder of the urinary system. Nephrectomy may be warranted.

Urinary obstruction, depending on location, can cause unilateral or bilateral flank and abdominal masses. Treatment is by correction of the obstructing lesion or by proximal decompression. A kidney rendered nonfunctional by back pressure is usually best removed. Obstructive uropathy may be suitable for in utero intervention. Decompressing the obstructed fetal urinary system may improve the postnatal status and increase survival.

Also known as autosomal recessive polycystic kidney disease. This entity involves both kidneys and carries a grim prognosis.

Typically presents within the first 3 days of life with hematuria and ≥1 flank masses. Maternal diabetes and dehydration are risk factors. Conservative management is generally recommended.

See Chapter 136.