Case Files Surgery, (LANGE Case Files) 4th Ed.

SECTION II. Clinical Cases

CASE 47

A 4-year-old boy informed his mother that he had just passed some blood in his urine. Hematuria was confirmed by the mother who brought the boy in for evaluation. The child denied any significant recent trauma, and he had been in good health. His past medical history is unremarkable. He is in the 56th percentile in height and in the 43rd percentile in weight. On physical examination, the patient appears healthy and has normal vital signs. Findings from the cardiopulmonary examinations are within normal limits. A 10-cm mass is identified in the left upper quadrant of the abdomen. This mass is firm and nontender. No abnormalities are noted in the extremities. Laboratory studies reveal a normal complete blood count (CBC) and electrolyte levels in the normal range. The urinalysis reveals 50 to 100 red blood cells per high-power field.

Images What is the most likely diagnosis?

Images What is the best therapy?

ANSWERS TO CASE 47: Wilms Tumor (Pediatric Abdominal Mass)

Summary: A 4-year-old boy presents with hematuria and an abdominal mass.

• Most likely diagnosis: Wilms tumor involving the left kidney.

• Best therapy: The management of a Wilms tumor depends on the findings from the imaging studies. If the tumor is massive or bilateral and an intracaval extension of tumor extends proximally to the hepatic veins, preoperative multiagent chemotherapy is used initially. These findings are uncommon, and the majority of Wilms tumors, even if large at the initial presentation, can be completely resected prior to chemotherapy. Almost all patients receive chemotherapy following nephrectomy. Radiation therapy is given if there has been tumor spillage, either from a preoperative capsular rupture or from an intraoperative tumor spill.

ANALYSIS

Objectives

1. Become familiar with the common presentation, differential diagnosis, and initial evaluation of an abdominal mass in newborns and pediatric patients.

2. Understand the management and outcome of a Wilms tumor and neuroblastoma.

Considerations

Wilms tumors are renal embryonal neoplasms that occur with a peak incidence in children between 1 and 5 years of age; thus at 4 years of age this patient is within this group. These tumors usually manifest as asymptomatic abdominal or flank masses, although hematuria is often seen. Optimal treatment of Wilms tumor consists of complete resection followed by adjuvant chemotherapy and radiation therapy, except for the small percentage of children with tumors that pose extreme low risk for recurrences. Before surgery, imaging evaluation is important to determine the extent of the tumor, and in this patient it should include abdominal ultrasonography and a CT scan of the abdomen and chest. If the tumor is unilateral and appears that it can be safely removed, surgical exploration and resection should be attempted.

Multiple combinations of chemotherapeutic agents have been studied by various studies sponsored by the National Wilms Tumor Study Group (NWTSG), and these agents have included vincristine, dactinomycin, doxorubicin, and cyclophosphamide in various combinations with or without adjuvant radiation therapy. Overall, for stage II patients, resection and adjuvant therapy have produced 4-year disease-free survival of 97.4%. For stage III disease, resection and adjuvant therapy have produced 4-year disease-free survival of 82%, and for stage IV patients, the 4-year disease-free survival with surgery and adjuvant therapy has been reported at 79%.

APPROACH TO: Abdominal Mass in the Pediatric Patient

The etiology of an abdominal mass in a pediatric patient depends to a large extent on the age of the patient at presentation. Knowing the age of the patient, the details of a directed history obtained from the child and the parents, and the results from a routine physical examination allow one to develop a focused differential diagnosis. Based on this list of possible etiologies, imaging studies and selected laboratory findings will then allow a more definitive diagnosis to be made. Table 47–1 lists the most likely etiologies of an abdominal mass for neonates (<1 month of age), and Table 47–2 lists the most likely etiologies for older infants and children.

Table 47–1 • ABDOMINAL MASSES IN NEONATES (BIRTH TO 1 MONTH)a

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Table 47–2 • ABDOMINAL MASSES IN INFANTS AND CHILDREN (1 MONTH TO 18 YEARS)a

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CLINICAL APPROACH

With the information in Tables 47–1 and 47–2, the etiology of the majority of abdominal masses can usually be determined with a high degree of certainty. A careful history should be obtained from the patient and the family that includes the length of time the mass has been present (or noticed), associated pain or other symptoms, changes in eating habits, changes in bowel or bladder function, associated fatigue or night sweats, associated bleeding or bruising, and other related conditions. An important consideration for neonates is the maternal prenatal history, especially data from prenatal ultrasound and information about the presence or absence of polyhydramnios. Maternal polyhydramnios may be the first sign of a neonatal bowel obstruction, which then may appear as an abdominal mass. The physical examination should document the location, size, consistency, and mobility of the mass, as well as associated lymphadenopathy or tenderness.

Radiographic Evaluations

Initially, plain abdominal radiographs are obtained to rule out gastrointestinal obstruction, to assess bowel gas patterns, and to determine the presence or absence of calcifications. Intra-abdominal calcifications in a neonate with an abdominal mass are often associated with complicated cystic meconium ileus. Calcifications in a different distribution can be associated with the diagnosis of neuroblastoma, especially in an older infant. If the findings from plain abdominal radiography are nonspecific, which is often the case, abdominal ultrasound is the next imaging modality of choice. Ultrasonography can usually identify the organ of origin, the mass can be classified as cystic or solid, and vascular flow characteristics can be determined using Doppler ultrasound techniques. Sonographic interpretation is very operator dependent and may be inaccurate in children.

CT scans are typically obtained if the ultrasonogram is either nondiagnostic or shows a solid tumor. CT imaging can provide additional anatomic detail and can be diagnostic. Because many of these conditions ultimately require operative intervention, a CT scan can provide an accurate preoperative assessment of the etiology of the mass and the involvement of adjacent structures; it can also detect the distant spread in case of neoplasms. The disadvantages of obtaining CT scans for children include the need for sedation in many cases and the unknown long-term effects of this level of ionizing radiation.

After the history is recorded, a physical examination performed, and selective imaging studies obtained, a short differential diagnosis is compiled. Very selective laboratory analyses can then be used to verify the diagnosis. For example, if the most likely diagnosis based on imaging is neuroblastoma, a CBC and a urine test for catecholamines should be obtained. If, however, the most likely diagnosis is hepatoblastoma, the level of α-fetoprotein should be evaluated prior to resection of the liver tumor.

COMPREHENSION QUESTIONS

47.1 A previously healthy 9-month-old boy is brought to the emergency department with severe, intermittent abdominal pain. During the attacks, which are episodic and occur every 10 to 15 minutes, the child draws his legs up to his abdomen. The child is vomiting and has heme-positive stools. On physical examination, a tender, mobile, sausage-shaped mass is found in the midabdomen. Which of the following is the most likely diagnosis?

A. Intussusception

B. Jejunal atresia

C. Neuroblastoma

D. Intestinal duplication cyst

E. Perforated appendicitis

47.2 A 5-year-old girl presents with a 7-cm, vague, left-sided abdominal mass. The patient has also experienced recent weight loss and failure to thrive. The mass is hard and fixed. A plain radiograph reveals fine calcifications in the region of the mass, and a CT scan shows an irregular, solid mass arising from the left adrenal gland. Which of the following conditions is the most likely?

A. Adrenal hemorrhage

B. Adrenal adenoma

C. Neuroblastoma

D. Wilms tumor

E. Intestinal duplication cyst

47.3 A 15-year-old boy presents to the emergency department with a fever of 38.9°C (102°F), a firm, fixed mass in the right lower quadrant of the abdomen, and a chief complaint of abdominal pain. The patient has been ill for the past 2 weeks but has not sought medical care until now. Which of the following findings is a CT scan of the abdomen most likely to demonstrate?

A. Neoplasm arising in an undescended testicle

B. Right hydronephrosis

C. Lymphoma

D. Abscess from a perforated appendix

E. Gastrointestinal stromal tumor

47.4 A 12-year-old girl presents with left lower quadrant pain, pelvic pain, and a vague fullness on physical examination. She is otherwise healthy and has no associated symptoms. Which of the following is the most likely imaging modality that would identify the etiology of the mass?

A. Plain abdominal radiograph

B. Upper gastrointestinal tract contrast study

C. Magnetic resonance imaging of the abdomen and pelvis

D. Ultrasound of the abdomen and pelvis

E. Positron emission tomography (PET) scan

ANSWERS

47.1 A. This is a classic and severe presentation of intussusception (when the bowel telescopes on itself). This infant should be treated with intravenous hydration followed by a barium or air contrast enema to both diagnose the condition and attempt to reduce the intussusception. If it cannot be reduced with the enema, an emergent operation is indicated.

47.2 C. Children with neuroblastoma are often symptomatic at presentation and suffer from failure to thrive. This is in contrast to children with Wilms tumor who usually appear healthy. Patients with neuroblastoma usually require tumor biopsy followed by neoadjuvant chemotherapy prior to tumor resection, again in contrast to the situation with Wilms tumor. The outcome with neuroblastoma depends on the biology of the tumor and the stage of disease, but overall is much worse than for Wilms tumor.

47.3 D. An abdominal mass in a previously healthy adolescent with fever and signs of systemic illness is most commonly an abscess from a perforated appendix, especially if it is located in the right lower quadrant. CT imaging or ultrasound can readily identify this as the likely diagnosis, and image-guided abscess drainage can be employed with plans for a delayed-interval appendectomy. This management option is preferable to urgent appendectomy and abscess drainage in this inflammatory condition.

47.4 D. This patient probably has an ovarian tumor, most likely benign. The most common of these tumors is an ovarian teratoma, which can easily be identified with pelvic ultrasound to fully examine the adnexa. None of the other imaging modalities would be the procedure of choice for this patient.

CLINICAL PEARLS

Images The most common cause of an enlarged renal mass in a neonate is hydronephrosis.

Images The most common presentation (60%) of a Wilms tumor is an asymptomatic upper abdominal or flank mass in a child 1 to 4 years of age.

Images A neonatal evaluation should include a review of the prenatal and delivery records.

Images Neuroblastoma is the most common type of retroperitoneal mass in a child older than 1 year.

Images Neuroblastoma is the most common solid extracranial malignancy in childhood and the most common malignancy in children under the age of one.

REFERENCES

Davidoff AM. Neuroblastoma. In Holcomb III GW, Murphy JP, eds. Ashcraft’s Pediatric Surgery. 5th ed. Philadelphia, PA: Saunders Elsevier; 2010:872-894.

Schamberger RC. Renal tumors. In Holcomb III GW, Murphy JP, eds. Ashcraft’s Pediatric Surgery. 5th ed. Philadelphia, PA: Saunders Elsevier; 2010:853-871.

Warner BW. Pediatric surgery. In: Townsend CM Jr, Beauchamp RD, Evers BM, et al, eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia, PA: Saunders Elsevier; 2008:2047-2089.