Wilms Tumor

Diagnosis

Wilms Tumor

Diagnosis

Wilms Tumor

History

Young girl with abdominal pain and masses on ultrasound

Findings

Right flank 10 x 10 x 11 cm mass with heterogeneous uptake, SUVmax between 0.8 amd 10.8. Adjacent mass or lymph nodes conglomerate medially measuring 4 x 3 x 7 cm, SUVmax 9.9.
Additional lymph nodes extending 4 cm CC, SUVmax of 10.9.
Two lung nodules, one measuring 3 mm too small to be characterized and the second on measuring 7.5 mm, SUVmax of 1.8.

Discussion

Wilms tumor is the most frequent pediatric renal tumor and around 6 percent of all pediatric cancers. It occurs mostly in children 5 years old and younger. The most common subtypic is triphasic Wilms tumor with the presence of stromal, epithelial and blastemal components in the specimen. Anaplasia is found in 5 percent of patients and associated with a worse prognosis .
Clinical presentation is insidious with non specific abdominal symptoms, fortuitous discovery of an abdominal mass. Hypertension or hematuria are present in 20 to 25 percent of cases.
Staging is performed using radiological modalities to assess surgical resectability, lymph node extension and pulmonary metastases, the later being present in 12 percent of patients.
Chest Computed Tomography is the modality of choice for the evaluation of lung lesions. Ultrasound for initial evaluation followed by Magnetic Resonance Imaging are the technique of choice for surgical planning, including the identification of renal vein, inferior vena cava and even atrial extension with occurs in up to 5 percent of patients.
FDG PET/CT is not a standard procedure for staging or the identification of relapse. In the evaluation of metastatic disease , it has not shown significant incremental value when compared to anatomical modalities. As in other neoplasms, infracentimetric lung lesions were not systematically identified with FDG PET/CT. Furthermore the presence of physiological FDG excretion in the urinary tract limits the evaluation of the primary lesion and post-operative residual disease when nephron sparing surgery are performed in bilateral cases. As expected, Wilms tumors with anaplasia demonstred higher FDG uptake but false negative lesions have been reported. In the few patients evaluated to date, reduction of SUVmax after neoadjuvant chemotherapy was associated with a better histological response but prognosis was not modified.
Survival is around 90 percent for localized disease (stage I-III) and 70 percent for metastatic disease (stage IV). Stage V is the presence of bilateral renal involvement. With the exception of stage I localized disease in small tumor and patients aged 2 years and younger, treatment is a combination of surgery, chemotherapy and in some radiotherapy.
Up to 5 percent of patients will have bilateral disease. It occurs more frequently in patients with underlying genetic predisposition such as Fanconi, Beckwith-Wiedemann, Denys-Drash and p53 alterations.

Key points

Differential Diagnosis:
Wilms tumor
Renal carcinoma
Mesoblastic nephroma
Cystic nephroma
Nephroblastoma
Rhabdoid tumor
Lymphoma

References

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