and male genital tract

Chapter 20 Urinary and male genital tracts




















































COMMON CLINICAL PROBLEMS FROM DISEASES OF THE URINARY AND MALE GENITAL TRACTS




Pathological basis of clinical signs and symptoms in the urinary and male genital tracts



















































Sign or symptom Pathological basis
Abnormal micturition  

Inflammation of the urethra, often accompanying a urinary tract infection

Obstructed urinary outflow, usually due to prostate gland enlargement

Incomplete bladder emptying due to obstructed urinary outflow

Severe obstruction to bladder outflow, usually due to prostate gland enlargement
Urethral discharge Urethritis, possibly due to sexually transmitted infections (e.g. gonorrhoea)
Scrotal swelling  

Inflammation or ischaemia of the testis

Enlargement of scrotal contents due to hernia, fluid (e.g. hydrocele), varicocele or tumour
Genital ulceration Often sexually transmitted infection (e.g. syphilis)
Bone pain If associated with male genital tract disease, possibly due to metastases from prostatic adenocarcinoma
Raised serum prostate specific antigen Secreted by prostatic carcinoma
Raised serum alpha-fetoprotein and/or human chorionic gonadotrophin Testicular germ cell neoplasia, particularly teratoma/non-seminomatous germ cell tumour
Gynaecomastia Possible manifestation of Leydig cell or germ cell tumour of testis
Infertility Impaired spermatogenesis due to endocrine disorders or to testicular lesions, or impaired ejaculation due to obstruction or to neurological disorders


URINARY CALCULI


Urinary calculi (stones) occur in 1–5% of the population in the UK, mainly those aged over 30 years, and with a male preponderance. They may form anywhere in the urinary tract, but the commonest site is within the renal pelvis. They present as:





Calculi form in the urine either because substances are in such an excess that they precipitate, or because other factors affecting solubility are upset. Factors influencing stone formation include the pH of the urine, which can be influenced by both bacterial activity and metabolic factors. Substances in the urine normally inhibit precipitation of crystals, notably pyrophosphates and citrates. The mucoproteins in the urine are thought to provide the organic nidus on which the crystals focus.


Calculi are classified according to their composition. The categories are:







Only 10% of patients with calcium-containing stones have hyperparathyroidism or some other cause of hypercalcaemia. However, most have increased levels of calcium in the urine, attributable to a defect in the tubular reabsorption. In the remaining patients, with idiopathic hypercalciuria, no known cause has been identified. The association of uric acid with calcium stones is probably because urates can initiate precipitation of oxalate from solution.


Magnesium ammonium phosphate stones are particularly associated with urinary tract infections with bacteria, such as Proteus, that are able to break down urea to form ammonia. The alkaline conditions thus produced, together with sluggish flow, cause precipitation of these salts, and large staghorn calculi form a cast of the pelvicalyceal system. Staghorn calculi remain in the pelvis for many years and may cause irritation, with subsequent squamous metaplasia or, in some cases, squamous carcinoma.


Uric acid stones occur in patients with gout (Ch. 7). Uric acid precipitates in acid urine. The stones are radiolucent.




RENAL CELL CARCINOMA




Predisposing factors


Tobacco smoking, obesity, radiation and acquired renal cystic disease are the main environmental risks for renal cell carcinoma. On average, current smokers have a 50% increased risk and about 25% of all renal cell carcinoma cases can be attributed to smoking. Renal cell cancer risk increases by 7% for each unit increase in body mass index, and overall the obesity risk accounts for about 25% of cases. The radiation risk is usually acquired through treatment of other cancers such as cervical and testicular cancer. Acquired cystic kidney disease, commonly seen in patients with renal failure on dialysis, results in a three- to four-fold increased risk of renal cell cancer.


Most cases of renal cell cancer are sporadic but there are some rare inherited disorders that predispose to development of this tumour. The most illustrative is von Hippel–Lindau (VHL) disease where there are mutations in the VHL gene, which normally produces a protein responsible for degrading proteins of the hypoxia-inducible factor (HIF) family. In the absence of this functioning protein there is accumulation of the HIF family of proteins, which in turn results in increased transcription of hypoxia-associated genes which promote cell growth, survival and angiogenesis. In VHL disease the risk of developing renal cell cancer is 70% by the age of 60 years with multiple and bilateral tumours; these patients are also at risk of epididymal, cerebral and other tumours (Ch. 26). The largest subgroup of sporadic renal cell carcinoma (clear cell carcinoma) has loss of expression of the VHL gene.











OBSTRUCTION


Obstruction of the ureter is the most frequent problem requiring clinical attention. Acute ureteric obstruction causes intense pain known as renal colic. The consequences of chronic ureteric obstruction are hydroureter and hydronephrosis. In both acute and chronic ureteric obstruction there is an increased risk of ascending infection, causing pyelonephritis. Ureteric obstruction may be either intrinsic or extrinsic.


Intrinsic lesions are within the ureteric wall or lumen; the most common is a urinary calculus. Calculi become impacted where the ureter is normally narrowed, that is at the pelvi-ureteric junction, where it crosses the iliac artery, and where it enters the bladder. Strictures may be congenital, when they occur at the pelvi-ureteric junction or in the transmural terminal segment of the ureter. Acquired strictures occur as a result of trauma and involvement by adjacent inflammatory conditions such as diverticulitis and salpingitis. Severe haematuria may cause obstruction due to blood clot.


Extrinsic factors cause pressure from without, and include primary tumours of the bladder and rectum, metastatic carcinoma in pelvic lymph nodes and benign hyperplasia of the prostate. Aberrant renal arteries may compress the ureter. Retroperitoneal fibrosis causes narrowing and medial deviation of the ureters and may either be due to drugs, such as methysergide, or be idiopathic.


Primary tumours of the ureter are transitional cell carcinomas. They may be multiple and are associated with urothelial tumours in the renal pelvis and bladder.










TRANSITIONAL (UROTHELIAL) CELL CARCINOMA OF THE BLADDER




Predisposing factors


Tobacco smoking and occupational exposures are the main environmental risks for transitional cell bladder cancer. On average, current smokers have a 300% increased risk and about 50% of all transitional cell bladder cancers can be attributed to smoking. This risk is due to the absorption of aromatic amines from cigarette smoke and their excretion in the urine. Aromatic amines have historically been present in industrial processes used to produce dyes, drugs and rubber, and a significant amount of bladder cancer could be attributed to industrial exposure to these chemicals. Most of these compounds were withdrawn from these processes in the 1950s, but there was a lag phase of new cancers developing from this exposure. Exposure to polycyclic aromatic hydrocarbons is a risk factor and these by-products of combustion are present in many industrial processes. It is estimated that 4% of European bladder cancer cases are due to this exposure, and this effect might be higher in countries with less regulated industries.


Genetic risk factors fall into two groups: genetic deficiencies of enzymes that would otherwise metabolise chemicals that are risk factors for bladder cancer (e.g. N-acetyl transferase), and genetic alterations in the tumours themselves. Although an oversimplification, there are two distinct genetic patterns in urothelial carcinoma. Papillary superficial tumours have relatively few and stable abnormalities. In contrast, solid invasive tumours have different alterations and tend to accumulate multiple abnormalities as they progress. However, molecular or genetic testing is not yet sufficient for diagnosis or follow-up.








PROSTATE GLAND



NORMAL STRUCTURE AND FUNCTION


The prostate gland surrounds the bladder neck and proximal urethra (Fig. 20.5). It consists of five lobes, separated by the urethra and ejaculatory ducts. Two lateral lobes and an anterior lobe enclose the urethra. The two lateral lobes are marked by a posterior midline groove, palpable on rectal examination. The middle lobe lies between the urethra and ejaculatory ducts and the posterior lobe lies behind the ejaculatory ducts. The normal gland weighs about 20g and is enclosed in a fibrous capsule.



From a pathology perspective, it is more useful to divide the prostate into zones. In early adult life the peripheral zone accounts for 70% of the organ, the transition zone (both sides of the proximal urethra) 5% and the central zone 20%. Prostate cancers arise almost exclusively from the peripheral zone. The transition zone gradually enlarges with age, and is the site of considerable enlargement in benign prostatic hyperplasia. Concentric groups of glands in all zones converge on ducts and open in the urethra.


Individual glandular acini have a convoluted outline, the epithelium varying from cuboidal to a pseudostratified columnar cell type depending upon the degree of activity of the prostate and androgenic stimulation. The epithelial cells produce prostate-specific antigen (PSA), acid phosphatase and the prostatic secretion that forms a large proportion of the seminal fluid for the transport of sperm. The normal gland acini often contain rounded concretions of inspissated secretions (corpora amylacea). The acini are surrounded by a stroma of fibrous tissue and smooth muscle.


The blood supply to the prostate gland is from the internal iliac artery by the inferior vesical and middle rectal branches. The prostatic veins drain to the prostatic plexus around the gland and then to the internal iliac veins. The nerves are from the pelvic plexus.




PROSTATITIS


Prostatitis means inflammation of the prostate; however, it is a confusing subject because of the substantial lack of correlation between the clinical symptoms, detection of neutrophils in prostatic secretions and an inflammatory infiltrate in histological samples. A causative organism is found in only 5–10% of cases; symptoms overlap with those of benign prostatic hyperplasia. The US National Institutes of Health (NIH) has published a consensus categorisation of prostatitis, and also a chronic prostatitis symptom index to tighten up clinical diagnosis:






In addition, there are patients with granulomatous inflammation of the prostate.









BENIGN PROSTATIC HYPERPLASIA




Benign prostatic hyperplasia (BPH) is the histological basis of a non-neoplastic enlargement of the prostate gland, benign prostatic enlargement (BPE), which occurs commonly and progressively after the age of 50 years. About 75% of men aged 70–80 years are affected and develop variable symptoms of urinary tract obstruction, benign prostatic obstruction (BPO). If severe and untreated, the hyperplasia may lead to recurrent urinary infections and, ultimately, impaired renal function.





Morphology


The hyperplastic process usually involves both lateral lobes of the gland. In addition, there may be a localised hyperplasia of peri-urethral glands posterior to the urethra and projectinginto the bladder adjacent to the internal urethral meatus (Fig. 20.6). This hyperplasia is described as ‘median’ lobe enlargement but does not correspond to the anatomical middle lobe.



The cut surface of the enlarged prostate shows multiple circumscribed solid nodules and cysts (Fig. 20.7). Histological examination reveals two components: hyperplasia both of glands and of stroma. The acini are larger than normal (some may be cystic) and are lined by columnar epithelium covering papillary infoldings (Fig. 20.8). The acini may contain numerous corpora amylacea. Phosphates and oxalates may be deposited around these to form prostatic calculi.




The stromal hyperplasia includes both smooth muscle and fibrous tissue. Some of the nodules are solid, being composed predominantly of stroma, and others also contain hyperplastic acini. Stromal oedema and periductal inflammation are common and may contribute to the urinary obstruction. Areas of infarction commonly occur, evident as yellowish necrotic areas with a haemorrhagic margin; these may result from obstruction to the blood supply by the hyperplastic nodules. There is often squamous metaplasia of prostatic ducts and acini at the edges of the infarct. Benign nodular hyperplasia is not a premalignant lesion.



Clinical features


There are four main factors in the development of obstructive symptoms:






The resulting obstruction to the bladder outflow produces various lower urinary tract symptoms (LUTS), which can be grouped as bladder sensation symptoms, storage symptoms and voiding symptoms; these have been incorporated into an International Prostate Symptom Score. Bladder sensation may be normal, increased or decreased. Storage symptoms include daytime frequency, nocturia, urgency and incontinence. Voiding symptoms include hesitancy, poor or intermittent stream, straining and dribbling.


Digital examination of the gland per rectum reveals enlargement of the lateral lobes, often asymmetrical. The gland has a firm, rubbery consistency, and the median groove is still palpable.


Acute urinary retention may develop in a man with previous LUTS; the bladder is palpably enlarged and tender, requiring catheterisation. This condition may be precipitated by voluntarily withholding micturition for some time, by recent infarction causing sudden enlargement of a hyperplastic nodule, or by exacerbation of local inflammation.


Chronic retention of urine is relatively painless. There may be increasing frequency and overflow incontinence, usually at night. The bladder is distended, often palpable up to the umbilicus, but is not tender since the distension is more gradual.


Jun 16, 2017 | Posted by in GENERAL SURGERY | Comments Off on and male genital tract

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