Inflammatory diseases of the urinary bladder (cystitis). Pathomorphological classification. Tumors of the kidney and urinary tract.
Cystitis
Cystitis is the inflammation of the urinary bladder, common symptoms include dysuria, frequency and urgency, it may or may not be associated with infection of the urethra. Common etiology is bacterial, thanks to E.coli, Proteus, Klebsiella and enterobacter which ascend through the urethral opening. Alternatively, Cystitis cystica and cystitis glandularis are reversible alterations to the urothelial which cause irritation, eosinophilic cystitis (autoimmune), follicular cystitis (lymphoid follicles in chronic cystitis), Hemorrhagic cystitis (side effect of radiation or cyclophosphamide).
Gross findings are nonspecific, but edema, hyperemia, petechiae and ulceration may all be evident. Histologically, edema and/or chronic inflammatory infiltrate of the lamina propria are present, although it's worth mentioning that tissue sampling in acute stage of disease is contraindicated. In disorders such as cystitis cystica and cystitis glandularis we see cystic spaces develop, lined with columnar epithelium which may also have a ring of transitional epithelium. More valuable than tissue sampling is urine analysis to observe bacteria in the urine.
Tumours
Most common benign tumour is cortical papillary adenoma, found in 40% of all adults and have no clinical significance.
Most common malignant tumour is renal cell carcinoma, followed by nephroblastoma (Wilms tumour).
Renal cell carcinoma
- Derived from renal tubular epithelium, mostly in the cortex
- 40% mortality rate, men more at risk, acquired cystic kidney disease (chronic dialysis) increases risk 30x
- Classification based on growth pattern:
- Clear cell carcinoma - composed of cells with clear cytoplasm, solitary and large. Gross appearance is yellow to white with areas of cystic softening and hemorrhage. Tumour commonly invades renal vein
- Papillary Renal Cell carcinoma - rarer, show papillary growth pattern, frequently multifocal and bilateral
Gross: renal cell carcinoma, 8 cm, in the lower pole – a well-circumscribed, lobulated, golden-yellow tumour (typical of the lipid-rich clear cell type) with dark foci of haemorrhage; normal kidney above.
Image: “Renal cell carcinoma” by Ed Uthman, MD (1953– ), Public domain, via Wikimedia Commons.
Example: a 65-year-old smoker with painless haematuria – think of urothelial (transitional cell) carcinoma of the bladder, the commonest tumour of the lower urinary tract. Other risk factors are aromatic amines (dye and rubber industry) and cyclophosphamide; chronic Schistosoma haematobium infection leads instead to squamous cell carcinoma.