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Radiology

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Department of Radiology

Seth G.S. Medical College and K.E.M. Hospital, Mumbai , India

Case of the Month

< Case No. 13 : June 2020 >

Wilms tumor

Contributed by Rahul Bhute

Other cases

Clinical Profile:

A 1.5 year old girl was brought by parents with complaints of rapidly increasing, painless abdominal lump since 15 days There was weight loss, shortness of breath and constipation. There was no pain, fever or hypertension.

On examination, there was a left sided, hard abdominal lump about 10x10cm; with smooth margins extending into the left hypochondriac region, epigastric and umbilical region - where it crossed ch was crossing the midline.

The mass did not move with respiration.

There were no signs suggestive of genitourinary malformations or syndromic features.

Radiological Investigations:

Abdominal radiograph (Fig. 1) shows a large, smooth, lobulated ill-defined soft tissue opacity occupying the left lumbar and left hypochondriac regions - the displacing bowel loops to the right. The superior margin of this lesion obscures the the splenic shadow. No calcific foci are seen. The bowel loops are of normal caliber and appropritely displced by the mass.

The contrast enhanced axial and coronal CT images show: (Fig. 2a,2b,2c) :

A large, heterogeneously enhancing, lobulated massmeasuring 12x8x15cm in relation to the superior pole of left kidney with mild dilatation of pelvicalyceal system. The mass is hypodense to the normal renal parenchyma and shows no calcific foci.. The kidney is displaced anteromedially. On post contrast images the lesion shows no renal vein or IVC extension. Both adrenal glands are seen separately from the mass lesion. There is enhancing soft tissue within the collecting system suggestive of tumour extension.

A large left renal mass separate from adrenal gland in a 1.5 year old child suggestive of Wilms tumour.

Fig. 1

Fig. 2a

Fig. 2b

Fig. 2c

Further clinical course:

The patient was admitted and the symptomatic management was started.

Routine blood investigations showed no significant abnormality.

Being a large sized mass with close proximity to the important structures and after multidisciplinary discussion the patient was advised preoperative chemotherapy for 21 days.

Nephrectomy is planned after the chemotherapy.

Discussion:

Wilms tumour is the most common childhood malignancy. The median age at diagnosis is 3.5 years.

•Perinatal diagnosis of Wilms tumor is possible, although it is not the most common tumor in this age group (1).

•Diagnosis of Wilms tumor after age 15 years is rare (2).

•Wilms tumor is typically found as an asymptomatic abdominal mass often discovered by a parent.

The National Wilms' Tumor Study - NWTS staging system*

This system relies on surgical and pathological evaluation of a tumor in patients not submitted to the preoperative chemotherapy.

Stage 1

(a) Tumor is limited to the kidney and completely excised

(b) The tumor is not ruptured before or during removal

(c) The vessels of the renal sinus are not involved beyond 2 mm

(d) There is no residual tumor apparent beyond the margins of excision

Stage 2

(a) Tumor extends beyond the kidney but is completely excised

(b) No residual tumor is apparent at or beyond the margins of excision

(c) Tumor thrombus in vessels outside the kidney is stage II if the thrombus is removed en bloc with the tumor

Stage 3

Residual nonhematogenous tumor is present and confined to abdomen

(a) Lymph nodes in the renal hilum, the periaortic chains, or beyond are found to contain a tumor

(b) Diffuse peritoneal contamination by the tumor

(c) Implants are found on the peritoneal surfaces

(d) Tumor extends beyond the surgical margins either microscopically or grossly

(e) Tumor is not completely resectable because of local infiltration into vital structures

Stage 4

Hematogenous metastasis or lymph node metastasis

Stage 5

Bilateral renal involvement

Syndromes associated with Wilms tumor:

•WAGR syndrome consisting of WT, aniridia, genital anomalies (cryptorchidism, hypospadias, etc), and mental retardation (3,4). This syndrome is characterized by germline deletion of chromosome 11p13 which carries the WT1 and PAX6 genes coding for WT and aniridia, respectively.

•Increased risk of developing WT is Denys-Drash syndrome consisting of pseudohermaphroditism and progressive glomerulonephritis leading to renal failure. This syndrome is caused by altered DNA-binding properties of the zinc finger region of the WT1 protein due to a dominant negative missense mutation.

•Beckwith-Wiedemann syndrome is another instance of increased risk of development of WT and occurs due to loss of function of the WT2 gene on chromosome 11p15.

•This syndrome is characterized by macroglossia, omphalocele, organomegaly, genitourinary anomalies, and increased risk of abdominal tumors.

•The insulin-like growth factor-2 gene expression has the greatest correlation with tumor predisposition in Beckwith-Wiedemann syndrome.

Management and Prognosis

•The treatment of Wilms tumor varies through-out the world. Complete nephrectomy remains the mainstay of treatment of unilateral Wilms tumor; however, the roles of neoadjuvant chemotherapy and biopsy vary.

•According to NWTSG protocols, primary surgery is followed by chemotherapy and sometimes radiation therapy on the other hand where SIOP protocols are followed, preoperative chemotherapy is used to decrease the risk of intraoperative tumor rupture and hemorrhage and to decrease the stage of the tumor at the time of surgery (5,6)

•The long-term prognosis of Wilms tumor has greatly improved over the past few decades, and the 5-year survival rate for disease localized to the abdomen now exceeds 90%.

•Overall survival is 70% for stage IV disease. Recurrence risk is largely dependent on histology. Early recurrence (within 2 years) occurs in 15% of tumors with favorable histology versus 50% of those with anaplastic histology. Anaplastic histology is associated with resistance to chemotherapy and poor prognosis.

References:

1. Kumar V, Abbas AK, Aster JC. Robbins and Cotran Pathologic Basis of Disease. Philadelphia, PA: Elsevier-Saunders; 2015.

2. Waseem M. Pediatric rounds: a 4-year-old boy with constipation and abdominal pain. Hospital Physician. 2004;40:23–27.

3. Isaacs H Jr. Fetal and neonatal renal tumors. J Pediatr Surg 2008;43(9):1587–1595

4. Scott RH, Stiller CA, Walker L, Rahman N. Syndromes and constitutional chromosomal abnormalities associated with Wilms tumour. J Med Genet 2006;43(9):705–715

5. Brisse HJ, Smets AM, Kaste SC, Owens CM. Imaging in unilateral Wilms tumour. Pediatr Radiol 2008;38(1):18–29

6. Green DM. The evolution of treatment for Wilms tumor. J Pediatr Surg 2013;48(1):14–19.

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