Page 500 - Concise Pathology for Exam Preparation ( PDFDrive )

16 Diseases of the Kidney and Lower Urinary Tract 485

• RCC produces a number of paraneoplastic syndromes due to abnormal hormone pro-
duction including polycythaemia due to elaboration of erythropoietin, hyperkalaemia,
hypertension, Cushing syndrome, leukaemoid reactions, amyloidosis, feminiza-
tion and masculinization.
• Tendency to invade renal vein and growth as a solid column even up to inferior vena
cava and right side of heart may be seen.
• RCC has a tendency for early and wide spread metastases before giving rise to any local
signs and symptoms. Most common sites are lungs and bones.

Prognosis
Five-year survival rate is about 45–70% in the absence of distant metastasis.

Q. Write briefly on Wilms tumour.
Ans. Wilms tumour/nephroblastoma is the most common primary renal tumour of
childhood. It has a peak age of 2–5 years and a sex ratio of 1:1. It is associated with three
syndromes:
1. WAGR syndrome, characterized by:
(a) Aniridia
(b) Genital anomalies
(c) Mental retardation
(d) Germline WT1 deletion followed by a nonsense or frame shift mutation of second
WT-1 allele (WT-1 gene is present at 11p13 and its protein product is a transcrip-
tional factor).
2. Denys–Drash syndrome, characterized by:
(a) Gonadal dysgenesis (male pseudohermaphroditism)
(b) Renal abnormalities (diffuse mesangial sclerosis leading to renal failure)
(c) Missense mutation of WT-1 affecting DNA-binding properties
3. Beckwith–Wiedemann syndrome, characterized by:
(a) Enlargement of the body organs (organomegaly)
(b) Hemihypertrophy, macroglossia, omphalocele, renal medullary cysts and abnormal
large cells in adrenal cortex (adrenocytomegaly)
(c) WT-2 abnormalities (WT-2 gene is present on 11p15.5; its function is unknown;
however, WT-2 mutation is known to increase the risk of Wilms tumour).

Morphology

Gross: Large, solitary, well-circumscribed mass, rarely bilateral or multicentric; soft,
homogeneous, tan to grey in colour; foci of haemorrhage and necrosis may be present.

Microscopic Features
• Recapitulates different stages of nephrogenesis. Typically shows a classic triphasic com-
bination of blastema (sheets of small blue cells), epithelial elements abortive tubules or
glomeruli) and stroma (fibrocystic or myxoid in nature).
• Rarely heterologous elements are identified including squamous or mucinous epithelium,
smooth muscle cells, adipose tissue, cartilage, osteoid and neurogenic tissue.

Clinical Features

Palpable abdominal mass, haematuria, pain and hypertension

Metastasis
• Through blood to lung and liver
• Renal (hilar) and paraaortic lymph nodes

Prognosis
Five-year survival rate is above 75%.

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