Urosurgery 22 Wilms tumor

• Nephroblastoma, also known as Wilms tumor, is the most common solid renal tumor of childhood.
• This embryonal tumor develops from remnants of immature kidney.
• The peak age for presentation is during the third year of life, and there is no sex predilection.
• Gene associated with Wilms tumor development (WT1), in chromosome 11p13

• Associated with
• - WAGR syndrome (Genitourinary abnormalities include hypospadias, cryptorchidism, and renal fusion)
• - Overgrowth syndrome -  Isolated hemihypertrophy and Beckwith–Wiedemann syndrome 
• - Denys-Drash syndrome - male pseudohermaphroditism, renal mesangial sclerosis, and nephroblastoma

• Wilms
• Aniridia
• Genitourinary malformation
• Mental retardation

• Knudson and Strong proposed a two-hit hypothesis to explain the earlier age of onset and bilateral presentation in children with a familial history of Wilms tumor.
• - Sporadic form of Wilms tumor results from two post-zygotic mutations in a single cell.
• - In contrast, the familial form of the disease arises after one prezygotic mutation and a subsequent postzygotic event

• Gross -
• • It is located in one of the poles of the kidney.
• • Large, multilobulated, and gray or tan in color with focal areas of hemorrhage and necrosis.
• • A fibrous pseudocapsule is occasionally seen

• Microscopic
• • It arises from embryonic connective tissue containing epithelial and connective tissue elements.
• • The typical Wilms tumor consists of blastemal, epithelial, and stromal elements in varying proportions
• • Malignant primitive glomeruli and primitive tubules, with epithelial and connective tissue cells exist side by side, one of the types is usually prominent

Triad of Mass, fever, haematuria.

• • Mass abdomen is commonest presentation. Mass is smooth, mobile, firm or hard, lobular, located in the loin, moves with respiration, bimanually palpable, ballotable, with dullness in renal angle and with resonant band in front. It does not cross the midline.
• • Fever—May be due to tumour necrosis.
• • Haematuria is a grave sign as it signifies rupture of tumour into the renal pelvis.
• • Hypertension—In 25% cases.

• Tumors too large for safe primary surgical resection
• Preoperative chemotherapy or radiation therapy is planned.

Unfavorable subgroup includes tumors that contain focal or diffuse elements of anaplastic cells or two other neoplastic entities considered not to be Wilms tumor variants, clear cell sarcoma of the kidney, and rhabdoid tumor of the kidney.

Favorable histology tumors comprise all Wilms tumors without anaplasia. Anaplasia is associated with resistance to chemotherapy.

• Adrenal neuroblastoma does not move with respiration and crosses the midline.
• Wilm's tumor moves with respiration and does not cross the midline.

• I. Disease confined to kidney and completely resectable
• II. Tumour extends beyond kidney, but can be excised completely
• III. Residual nonhematogenous tumor confined to abdomen.
• IV. Hematogenous metastases to lung, liver, bone, and brain.
• V. Bilateral disease

• A. Surgical Measures
• B. Chemotherapy
• C. Radiation therapy

Uilateral Wilm's tumor (tumors not crossing the midline or involving adjacent visceral organs) -  radical nephrectomy. Retroperitoneal lymph node dissection is not of proven value and is not recommended. Tumor extending into the vena cava should be removed unless there is evidence of total obstruction.

Bilateral Wilms tumor - preoperative chemotherapy followed by renal-sparing surgery

• Favorable histology 
• Stage I, II - Surgery + adjuvant chemotherapy
• Stage III, IV - Surgery + Chemotherapy + radiotherapy 
• Stage V - Bilateral biopsy + Chemotherapy + Second look surgery 

• Unfavorable histology 
• Stage I - Surgery + Chemotherapy 
• Stage II-IV (focal anaplasia) - Surgery + Chemo + Radiotherpy 
• Stage II-IV (anaplastic) - Adjuvant chemotherapy 
• Stage V - Bilateral biopsy + Chemotherapy + Second look surgery 

Chemotherapy agents used are vincristine,doxorubicin, cyclophosphamide, and etoposide

• Stage III or IV disease with favorable histology
• Stages II–IV with focal anaplasia and clear cell sarcoma
• All stages of rhabdoid tumor of the kidney.