Wilms' tumour typically manifests between the ages of 2 and 5 years, with a median age of diagnosis of 3 years. It is slightly more common in females than males. While the exact cause is unknown, certain genetic syndromes and specific genetic alterations, including mutations in Wilms tumour 1 (WT1) and Wilms tumour 2 (WT2) genes predispose individuals to Wilms’ tumour. Associated syndromes are Beckwith-Wiedemann syndrome, WAGR (Wilms tumour, Aniridia, Genitourinary anomalies, and mental Retardation) Denys-Drash syndrome (DDS), Perlman syndrome, Frasier syndrome and isolated hemihypertrophy (Liu & Suson, 2020; Holcomb et al., 2014). Wilms’ tumour is mostly unilateral, however, bilateral Wilm’s tumours are seen in about 5-7% of patients (Ibiyeye et al.,2018)

WT exhibits a triphasic pattern consisting of three elements: blastemal, epithelial, and stromal elements. Tumours may contain various proportions of each of these elements, triphasic pattern is characteristics of most Wilms’ tumour, however some tumours can have monophasic or biphasic patterns. Tumours may also vary in size and aggressiveness, with favourable histology (triphasic pattern) having a better prognosis compared to unfavourable histology, which is characterized by focal or diffuse anaplasia (Holcomb et al., 2014)

In this environment, Burkitt lymphoma (BL) is a key differential diagnosis for Wilms tumour. Children with abdominal BL are typically more malnourished, and their tumours grow rapidly, ultrasound may show single or multiple solid homogeneous masses. BL can extensively infiltrate the kidneys, leading to uniform enlargement. Neuroblastoma is another important differential, usually presenting in an advanced stage with children in worse clinical condition. These patients may experience severe pain, anaemia, profuse sweating, diarrhoea, tremors, and characteristic features like subcutaneous nodules or bilateral orbital metastasis ("raccoon eyes"). Imaging, including ultrasound and CT, commonly shows a suprarenal mass with calcifications in 80–90% of cases Isreals et al., 2013). Other differential diagnosis include abdominal tuberculosis, hepatoblastoma, ovarian teratoma and other rare renal tumours such as clear cell sarcoma of the kidney, and renal cell carcinoma.

The usual presentation is an asymptomatic abdominal mass or swelling. Other modes of presentation may include abdominal pain, haematuria and hypertension. Occasionally, patients may present with systemic symptoms such as fever and weight loss. (Holcomb et al., 2014; Isreals et al., 2013). Atypical presentations include cases where the classic painless abdominal mass is absent. Instead, symptoms may manifest as severe abdominal pain, isolated hypertension without a detectable mass, haematuria as the initial complaint, or urinary obstruction due to tumour involvement of the renal pelvis. 

Stage I: The tumour is limited to the kidney and can be completely removed surgically.

Stage II: The tumour has spread beyond the kidney to nearby structures, such as the renal capsule or the blood vessels of the kidney but can still be completely removed by surgery.

Stage III: The tumour has spread beyond the kidney to other tissues within the abdomen and cannot be completely removed by surgery.

Stage IV: The tumour has spread to distant organs such as the lungs, liver, bones, or brain.

Stage V: Both kidneys have tumours at diagnosis (Holcomb et al., 2014). 

The diagnosis of Wilms tumour can be made with reasonable certainty based on history, physical examination, and radiologic investigations such as: 

1. Ultrasonography (USS) of the abdomen is extremely useful to confirm the diagnosis especially in resource limited settings where Computed Tomographic (CT) scan may not be available. USS is non-invasive and reliable in the diagnosis of renal tumours in children.  In a patient with WT, it will show a solid tumour arising from the kidney, the size of the tumour, involvement of surrounding structures, presence or absence of tumour in the contralateral kidney, and liver metastasis. 
2. Abdominal CT scan with intra-venous contrast:  this is very useful for stagging of Wilm’s tumour, it will show most of the features seen on ultrasound but with a better resolution. It will also show presence or absence of tumour thrombi in the renal vein and inferior vena cava, excretion of contrast from the contralateral kidney (which confirms that the kidney is functional). The draw back of CT scan use in children is the risk of exposure to radiation. 
3. Intravenous urography (IVU): In the setting where CT scan is not available, IVU should be done to confirm excretion of contrast from the contralateral kidney, to ascertain that the contralateral kidney is functioning.
4. Chest x-ray: to detect lung metastases that present as white round lesions often in the periphery of the lungs.

Other investigations such as serum electrolyte, urea and creatinine, liver function test and full blood count are required before administration of chemotherapy and surgery. (Holcomb et al., 2014; Isreals et al., 2013)

Note: tumour biopsy is generally avoided due to the risk of tumour spillage and upstaging of the tumour.

The mainstay of treatment for Wilms' tumour is multimodal therapy, including surgery (nephroureterectomy), chemotherapy, and sometimes radiation therapy. 

There are two main treatment protocols: 

International Society of Paediatric Oncology (SIOP) protocol: this protocol involves administration of upfront pre-operative chemotherapy following confirmation of a renal tumour via USS or CT scan, followed by surgery then post-operative chemotherapy with/without radiotherapy depending on the stage of the tumour and risk stratification (Holcomb et al., 2014; Isreals et al., 2013)

Children Oncology Group (COG) protocol: this protocol involves an upfront surgery, histologic diagnosis of Wilms’ tumour using the excised kidney and post-operative chemotherapy with/without radiotherapy depending on the stage of the tumour and risk stratification. (Holcomb et al., 2014)

Note: Reliable and timely pathology services have an important role in making a histological diagnosis and in determining the postoperative chemotherapy. Postoperative chemotherapy is then based on the tumour type (risk classification) and stage at surgery. Stratifying tumours into low-, intermediate- and high-risk groups is based on histological sub-classification (Isreals et al., 2013).

Supportive care: This includes adequate nutritional assessment and nutritional support for malnourished patients, transfusion of appropriate blood products to correct anaemia and other haematological abnormalities. antibiotic therapy for febrile neutropenia, adequate pain control, provision of social, spiritual, emotional, and psychological support for patients and their families (Isreals et al., 2013).  

Bilateral Wilms’ tumour: both SIOP and COG protocols recommend pre-operative chemotherapy followed by Nephron sparing surgery (Holcomb et al., 2014; Isreals et al., 2013).

After completion of therapy, close monitoring is essential to detect any disease recurrence or late effects of treatment. Follow-up visits typically involve physical examination, abdominal ultrasound, and laboratory tests. Follow-up challenges include treatment abandonment and loss to follow-up. These patients may present later with tumour relapse and long-term complications of chemotherapy and radiotherapy, such as secondary malignancies.

Overall, the prognosis for Wilms' tumour is favourable, with an estimated 5-year survival rate exceeding 90% for children with favourable histology. Outcomes for those with metastatic tumours with favourable histology are equally excellent. However, outcomes may vary depending on factors such as histology, stage, age at diagnosis, tumour weight and response to therapy (Abib et al., 2022; Holcomb et al., 2014).

Wilms' tumour is a rare but curable childhood cancer that requires prompt diagnosis and multimodal therapy for optimal outcomes. Capacity building, early presentation, improved supportive care, treatment guideline adapted to local resources and social support are essential to improving outcomes in low- and middle-income countries. Patients presenting to peripheral hospitals should be referred early to a hospital with facilities and expertise for diagnosis and treatment; a hospital where the patient will have the best chance of cure.