History and physical
A 9-month-old female presented with a 2-month history of abdominal distension and weight loss.
The patient underwent an uncomplicated birth following an unremarkable pregnancy at 39-weeks gestational age via elective caesarean section. The toddler attained normal developmental milestones aside from the inability to roll prone from supine. Initially at the 70th percentile at birth for weight, she presented at the 30th percentile with stable height and head circumference (50th percentile). The patient did not exhibit any clinical features of Beckwith Wiedemann Syndrome including omphalocele, macroglossia and macrosomia.
There is no consanguinity, no family history of recurrent malignancies, haematological or renal conditions.
Investigations
Initial limited ultrasonographic study of the abdomen demonstrated massively enlarged kidneys with loss of corticomedullary differentiation. The right kidney measured 13.1 cm and the left measured 15 cm (normal approximately 6 cm) [1]. Multiple ill-defined hypoechoic areas were seen randomly interspersed within the renal parenchyma bilaterally suggesting presence of nephrogenic rests and therefore nephroblastomatosis. It was not possible to rule out the presence of Wilms tumour within the nephrogenic rests on ultrasound. No evidence of hydronephrosis, hydroureter or free fluid was seen.
Computed tomography (CT) of the abdomen and pelvis with IV and oral contrast demonstrated homogenous, diffuse, renal enlargement and loss of normal architecture with renal parenchyma replaced by homogenous low attenuating peripheral masses bilaterally (Fig. 1). There were two ill-defined hypodense areas in the medial aspect of the left kidney concerning for malignancy. Residual normal renal parenchyma was present as areas of striate enhancement, hyperdense in comparison to the thick rind of peripheral nodules. Based on clinical presentation and CT findings, the patient was diagnosed with bilateral DHPLNB.
Gadolinium enhanced magnetic resonance imaging (MRI) of the abdomen performed after 6 weeks of chemotherapy demonstrated hypointense peripheral masses on T1/T2 images with thick septations suggestive of bilateral DHPLNB. A small heterogeneously enhancing lesion with multiple small linear and round cysts in the medial left kidney was characterized on T1 imaging, suspicious for a superimposed Wilms tumor (Fig. 2). Diffusion weighted imaging was not conducted.
No metastases were seen on CT chest with contrast. Pathology after left partial nephrectomy confirmed Wilms tumor.
Cytogenetic analysis was conducted revealing a normal female karyotype (46XX). No other tumour markers or genetic testing was performed.
Differential diagnosis
Treatment/intervention
The patient was treated with COG protocol AREN 0534 EE-4A chemotherapy, including vincristine and dactinomycin for 20 weeks. Due to the presence of the superimposed left renal mass, a left partial nephrectomy and perihilar lymph node dissection was performed. Following the surgery, she also received left flank radiotherapy to a dose of 1080 cGy in 6 fractions.
Outcome and follow-up
Pathology was consistent with DHPLNB and resection of a Wilms tumor. Resection margins were positive. Nodal dissection was negative. Following surgical resection and chemotherapy, the patient was followed with MRI every 3 months for a year. Thereafter, the patient was followed with MRI every 6 months for 2 years. Currently, the patient is now on surveillance with ultrasounds every 3–4 months.