Comprehensive notes on lower urinary tract disorders. Delve into bladder anatomy, ureteral obstruction, renal calculi, vesicoureteral reflux, and retroperitonea
DISORDERS OF THE LOWER URINARY TRACT — Revision Notes --- CLINICAL ANATOMY Urothelium - Lines renal pelves, ureters, bladder, and urethra (except terminal portion) - 5–6 cell layers; oval nuclei with linear nuclear grooves - Surface layer = large flattened "umbrella cells" with abundant cytoplasm - Bladder Wall Layers - Lamina propria contains wisps of smooth muscle forming a discontinuous muscularis mucosa - Muscularis propria (detrusor muscle) = deeper, larger, well-defined muscle bundles - IMPORTANT: Bladder cancers are staged based on invasion of the detrusor muscle - Obstruction raises intravesical pressure, causing muscle hypertrophy - Key Anatomical Relationships - Ureters are retroperitoneal — vulnerable to entrapment by retroperitoneal tumors or fibrosis - Women: uterine prolapse pulls bladder floor down, creating a cystocele (bladder protrudes into vagina, fails to empty properly) - Men: prostate lies posterior/inferior to bladder neck — enlargement is a major cause of urinary obstruction - --- URETERS Congenital Anomalies- Found in 2–3% of autopsies; most are clinically insignificant - UPJ (Ureteropelvic Junction) Obstruction — most common cause of hydronephrosis in infants and children - - Early-life cases: predominantly male, bilateral in 20%, often associated with other anomalies (including contralateral renal agenesis in a minority) - Adult cases: more common in women, usually unilateral - Cause: abnormal smooth muscle organization, excess collagen deposition at UPJ, or rarely extrinsic compression by abnormal renal vessels Tumors and Tumor-Like Lesions- Primary ureteral tumors are rare - Benign tumors = mesenchymal origin; e.g., fibroepithelial polyp (loose vascularized connective tissue overlaid by urothelium, common in children) - Malignant tumors = mostly urothelial carcinomas; peak in 6th–7th decade; cause ureteral obstruction; commonly concurrent with bladder or renal pelvis urothelial carcinomas - Obstructive Lesions - Obstruction leads to hydroureter, hydronephrosis, and pyelonephritis - Unilateral obstruction = proximal intrinsic or extrinsic causes - Bilateral obstruction = distal causes (e.g., prostatic nodular hyperplasia) - Intrinsic Causes - Calculi (renal origin, usually 6 weeks, with no infection or identifiable cause - Symptoms: intermittent severe suprapubic pain, frequency, urgency, hematuria, dysuria - Cystoscopy: mucosal fissures and punctate hemorrhages (glomerulations) - Microscopy: nonspecific; mast cells often increased in submucosa (significance uncertain) - Biopsy main role = rule out CIS (clinically mimics interstitial cystitis) - Some cases have chronic mucosal ulcers = Hunner ulcers (late/classic/ulcerative phase) - Late course: transmural fibrosis → contracted bladder - Treatment: largely empiric - Malakoplakia - Chronic inflammatory reaction due to acquired defects in phagocyte function - Setting: chronic bacterial infection (mostly E. coli, occasionally Proteus); increased in immunosuppressed (e.g., renal transplant recipients) - Cystoscopy: soft yellow, slightly raised mucosal plaques (3–4 cm) - Microscopy: large foamy macrophages + multinucleate giant cells + lymphocytes; macrophages have granular cytoplasm (phagosomes with bacterial debris due to defective phagolysosome function) - Michaelis-Gutmann bodies: laminated mineralized concretions (calcium deposited in enlarged lysosomes) within macrophages — pathognomonic - Similar lesions occur in colon, GI tract, brain, lungs, bones, endometrium, kidneys, prostate, epididymis - Polypoid Cystitis - Inflammatory lesion from bladder mucosal irritation, most commonly due to indwelling catheters - Urothelium forms broad bulbous polypoid projections due to submucosal edema - Can be mistaken for papillary urothelial carcinoma (clinically and histologically) - --- Metaplastic Lesions Cystitis Glandularis and Cystitis Cystica - Von Brunn nests = urothelial nests grow downward into lamina propria - Center cells undergo metaplasia: - - Cuboidal/columnar appearance = cystitis glandularis - Retract to form cystic spaces lined by flattened urothelium = cystitis cystica - Both often coexist = cystitis cystica et glandularis - Variant with goblet cells resembling intestinal mucosa = intestinal/colonic metaplasia - Extensive multifocal intestinal metaplasia = precursor to adenocarcinoma - Squamous Metaplasia - Response to chronic injury; urothelium replaced by nonkeratinizing or keratinizing squamous epithelium - Distinguished from normal glycogenated squamous epithelium at trigone in women - Extensive multifocal keratinizing squamous metaplasia = precursor to dysplasia, CIS, and invasive squamous cell carcinoma - Classic sequence: bladder schistosomiasis → squamous metaplasia → squamous cell carcinoma - Nephrogenic Adenoma - May not be true metaplasia; evidence shows some caused by implantation of renal tubular cells at sites of bladder erosion (shown in renal transplant recipients) - Urothelium replaced by cuboidal epithelium, sometimes papillary - Usually 95% are epithelial origin; urothelial (transitional cell) neoplasms most common, then squamous, then glandular - Urothelial neoplasms = ~90% of all bladder tumors - Epidemiology - Male:female ratio = 3:1 - Higher incidence in high-income nations and urban dwellers - 80% of patients are 50–80 years old - Rarely familial - Risk Factors - Cigarette smoking: 3–7x increased risk (depending on duration and type) - Industrial aryl amine exposure (e.g., 2-naphthylamine): cancer appears 15–40 years after first exposure - Schistosoma haematobium: 70% squamous carcinomas in endemic areas - Long-term analgesic use - Heavy long-term cyclophosphamide use - Irradiation - Two Precursor Pathways to Invasive Carcinoma Feature Noninvasive Papillary Tumors Flat CIS --- --- --- Origin Papillary urothelial hyperplasia Flat urothelium Grade Low or high grade Always high grade Mutations FGFR3, RAS, PI3-kinase (gain-of-function) p53, RB (loss-of-function) Progression ~20% progress to muscle invasion 50–75% progress to invasion if untreated --- Urothelial Tumors — Classification Papilloma - 1% or less of bladder tumors; younger patients - Small (0.5–2 cm), delicate, attached by a stalk (exophytic) - Finger-like papillae: fibrovascular core covered by histologically normal urothelium - Recurrence and progression rare - Inverted Papilloma - Completely benign; inter-anastomosing cords of bland urothelium extending into lamina propria - Simulates invasive process but is benign - PUNLMP (Papillary Urothelial Neoplasm of Low Malignant Potential) - Thicker urothelium with greater cell density than papilloma - Larger than papillomas at cystoscopy - Recurrence with same morphology; rare progression to higher grade - Low-Grade Papillary Urothelial Carcinoma - Orderly architecture, low-grade cytologic atypia - Evenly spaced, cohesive cells with maintained polarity - Scattered hyperchromatic nuclei, infrequent mitoses (mostly basal), slight nuclear variation - May recur and occasionally invade; rarely life-threatening - High-Grade Papillary Urothelial Carcinoma - Dyscohesive cells, large hyperchromatic nuclei, irregular chromatin, prominent nucleoli - Highly anaplastic cells; frequent mitoses including atypical forms - Architectural disarray and loss of polarity - High incidence of progression to muscle-invasive cancer; significant metastatic potential (lymph nodes, liver, lung) - Carcinoma In Situ (CIS) / Flat Urothelial Carcinoma - Cytologically malignant cells confined to flat urothelium (no basement membrane invasion) - Always considered high grade - Ranges from full-thickness atypia to pagetoid spread (scattered malignant cells in otherwise normal urothelium) - Lacks cohesiveness → cells shed into urine - Cystoscopy: mucosal reddening, granularity, or thickening — no intraluminal mass - Commonly multifocal; may extend to ureters and urethra - If untreated: 50–75% progress to invasive cancer - Invasive Urothelial Carcinoma - May be associated with