136: Surgical Diseases of the Newborn: Retroperitoneal Tumors

A neuroblastoma is a primitive malignant neoplasm that arises from neural crest tissue. Usually, it is located in the adrenal gland, but it can occur anywhere neural crest cells migrate. It is the most common extracranial solid malignancy of childhood. Incidence is ∼1 per 100,000 children in the United States.

This tumor typically presents as a firm, fixed, irregular mass extending obliquely from the costal margin, occasionally across the midline, and into the lower abdomen

1. Laboratory studies. A 24-hour urine collection should be analyzed for vanillylmandelic acid and other catecholamine metabolites. Elevated lactate dehydrogenase is associated with poor prognosis.

2. Imaging and other studies. A plain abdominal radiograph may reveal calcifications within the tumor. Computed tomography (CT) typically shows extrinsic compression and inferolateral displacement of the kidney. Metastatic evaluation involves bone marrow aspiration and biopsy, bone scan, chest radiograph, and chest CT.

Treatment is based on stage. Complete surgical resection remains the best hope for cure unless the infant has type 4S disease, which is associated with spontaneous regression. Planned therapy should take into account this well-recognized but poorly understood fact. Advanced tumors require multimodality therapy with surgery, radiation, and chemotherapy, but this is uncommon in neonates.

A mesoblastic nephroma is embryonic solid renal tissue that is not usually malignant.

A palpable mass is found on abdominal examination, or a solid kidney mass is seen on prenatal ultrasound

1. Physical examination. The mass is found on examination in the newborn period or becomes apparent in first few months of life.

2. Imaging and other studies. Ultrasonography is obtained when a solid mass is identified in the neonate

1. Surgery. Nephrectomy is indicated and includes lymph node sampling to assess for rare malignant degeneration.

A Wilms tumor is an embryonal renal neoplasm in which blastemic, stromal, and epithelial cell types are present. Renal involvement is usually unilateral but may be bilateral (5% of cases).

A palpable abdominal mass extending from beneath the costal margin is the usual mode of presentation.

Aniridia, hemihypertrophy, certain genitourinary anomalies, and a family history of nephroblastoma are well recognized

1. Laboratory studies. No tumor marker is available.

2. Imaging and other studies. Ultrasonography is generally followed by CT, which reveals intrinsic distortion of the calyceal system of the involved kidney. The possibility of tumor thrombus in the renal vein and inferior vena cava should be evaluated by ultrasonography.

Multimodality therapy combining surgery, radiation, and chemotherapy is the standard.

1. Unilateral renal involvement. Radical nephrectomy with lymph node sampling is indicated. Surgical staging determines the need for radiotherapy and chemotherapy. Both are effective.

2. Bilateral renal involvement. Treatment of bilateral tumors is highly individualized. Neoadjuvant therapy followed by nephron-sparing resection may be attempted.

A teratoma is a neoplasm containing elements derived from all 3 germ cell layers: endoderm, mesoderm, and ectoderm. Neonatal teratomas are primarily sacrococcygeal in location. They may represent a type of abortive caudal twinning.

This tumor is usually grossly evident as a large external mass in the sacrococcygeal area. Occasionally, it may be presacral and retroperitoneal in location or may present as an abdominal mass.

See Section II. Most sacrococcygeal teratomas are identified on prenatal ultrasound. Digital rectal examination of the presacral space is important. α-Fetoprotein levels should be assayed.

The incidence of malignant tumors increases with age. Prompt surgical excision is required.