This case study describes a 3-year old female who presented with abdominal pain and was diagnosed with Stage III Wilms tumor with unfavorable histology. Tests including ultrasound, CT scan and biopsy confirmed the diagnosis and showed the tumor had spread to nearby lymph nodes. The patient underwent chemotherapy followed by surgical removal of the left kidney, adrenal gland and tumor. Histological examination found features typical of Wilms tumor including blastema, epithelium and stroma components as well as metastases in the lymph nodes. As unfavorable histology carries a lower survival rate, the patient will require ongoing surveillance.

1. A PEDIATRIC ABDOMINAL MASS CASE STUDY
Lauren. P. Polli1, Katrina Conard, MD2; 1Drexel University College of Medicine, Philadelphia, PA 19102 2Department of Pathology, Alfred I.
duPont Hospital for Children, Wilmington, DE 19803
Acknowledgments
Special thanks are extended to Steve Phillips, Heather Hardy, and
Linda Krawczuk.
Abstract
A nephroblastoma, commonly known as a Wilms Tumor, is a rare
malignant embryonal neoplasm derived from nephrogenic blastemal
cells (Murphy). This tumor is predominantly in the pediatric population
with 98% of the cases occurring under the age of 10. It is the fourth most
common type of cancer in children. The mean age of occurrence for
males is 36 months and females is 42 months. Risk factors include
female gender, African American race and a positive family history.
Certain abnormalities are associated with this disease such as aniridia,
hemihypertrophy, undescended testicles and hypospadia. Wilms
Tumors are a part of certain syndromes including WAGR syndrome,
Denys-Drash syndrome and Beckwith-Wiedemann syndrome. Only 400-
500 new cases are diagnosed a year. Current treatments for Wilms
Tumors with favorable histology (95% of Wilms Tumors) have an 85-90%
cure rate.
This case study is about a 3 year old female who presented to Alfred I.
duPont Hospital for Children with a classic Wilms Tumor case.
Introduction
On April 8, 2012 a 3 year old female presented to the A.I. duPont
Emergency Department with a chief complaint of abdominal pain. She
had diarrhea, normal urine output, normal vitals and was afebrile. She
refused to eat but would drink. Blood work showed mild anemia, LDH of
2731 mmol/L (normal 500-920 mmol/L), and increased white blood cells
(neutrophils). On physical exam she had abdominal pain and
distention with a palpable firm mass on the left side. An ultrasound
showed a heterogeneous mass arising from the left kidney. A CT scan
and biopsy were scheduled.
Initial differential diagnoses included Wilms Tumor or Neuroblastoma.
Methods
An ultrasound guided needle biopsy was preformed and showed a
Stage III Wilms Tumor with unfavorable histology and diffuse anaplasia.
A port was placed and chemotherapy began on April 14, 2012. On
July 16, 2012 a left nephrectomy was preformed to remove the left
kidney, adrenal gland and tumor plus additional lymph nodes.
A standard work up for a suspected Wilms Tumor patient include X-
ray, ultrasound, CT scan, CBC and urinalysis. Treatment includes a
combination of nephrectomy, chemotherapy and/or radiation.
Results
The surgical specimen consisted of the left kidney, adrenal gland
and tumor; left perinephric lymph node; left paraaortic lymph node
and 2 paracaval lymph nodes. The kidney and tumor weighed 692
grams (normal= 48.4 g) and measured 14.5 x 10 x 6 cm.
The typical histological appearance of a Wilms Tumor displays the
various stages of both normal and abnormal nephrogenesis.
Blastema, epithelium and stroma are the 3 components that make up
a Wilms Tumor. Both the needle biopsy and nephrectomy specimen
showed the same histologic features. Most of the cells in the tumor
are primitive, undifferentiated cells with scant cytoplasm. The nuclei
are large, round to oval, hyperchromatic and irregular. Nuclear
molding can also be seen. Multiple abnormal mitoses are identified.
Attempted tubule formation, which can be seen, is a dominant
feature of the tumor.
Both intralobular and periolobular nephrogenic rests were
identified within the kidney. The renal artery, renal vein and ureter
were uninvolved by tumor on permanent sections.
Immunohistochemistry was used to identify metastatic disease in the
lymph nodes. The WT-1 stain was used and confirmed metastases
and micrometastases in all lymph node specimens.
Conclusion
The patient was entered into a Children's Oncology Group (COG)
study at the time of her initial diagnosis based upon the needle
biopsy. This study laid out a specific protocol for the patient’s
chemotherapy treatment prior to her nephrectomy. These studies
include large pools of patients collected from across the country.
Each patient is given a specific protocol for treatment and specimen
examination to research the efficacy of different treatments. In the
pathology department, once the specimen is removed 10 grams of
snap frozen tissue is required from the primary tumor site and from
normal kidney. The tumor is then staged based on macroscopic
features such as tumor size, tumor focality and extent of tumor as well
as microscopic features such as histological type, nephrogenic rests
and metastases. Based on the COG staging system, this patient was
classified as a Stage III.
Nephrogenic rests are “abnormally retained embryonic kidney
precursor cells arranged in clusters” (NCI). They are seen in 35% of
kidneys with unilateral Wilms tumors and virtually every kidney with
bilateral Wilms Tumors. Patients with nephrogenic rests in a kidney
removed for Wilms Tumor are at increased risk for developing a tumor
in the remaining kidney. This risk decreases with age.
Patients with unfavorable histology (5% of Wilms Tumors) such as this
one, have a 72% 4-year survival rate at Stage III. She will need
continued surveillance for years to come to ensure a bilateral
tumor does not occur.
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Figure 1- Abdominal CT Scans showing large mass on left kidney.
Figures 2 & 3- Gross images of nephrectomy specimen external surfaces.
Figures 4 & 5- Gross images of nephrectomy specimen cut surfaces.
Figures 6 & 7- Histologic appearance of Wilms Tumor
Figures 8 & 9- Histologic appearance of Wilms Tumor