The penis and scrotum231
22.2 The prostate232
The male genital tract consists principally of the penis, foreskin, testes, epididymes and prostate gland. A large range of disease processes affect the male genital tract, but inflammation and tumours are probably the most important clinically. Malignancies of the testis and prostate are particularly common tumours and it is important that you have a working knowledge of these. Sexually transmitted diseases (STDs) are also seen and may affect a variety of organs in the male genital tract. Congenital diseases are also common and vary from the relatively insignificant (overly long foreskin) to the very significant (e.g. the maldescended testis with the associated increased risk of malignancy).
22.1. The penis and scrotum
The penis is a skin-covered organ (as is the scrotum) and can therefore exhibit many of the common skin disorders (e.g. eczema/dermatitis). In addition, the penile urethra may be susceptible to tumours of the urothelium (proximally) and squamous epithelium (distally).
Congenital disorders
Abnormalities include an excessively small penis (micropenis) or a urethra that opens either on the ventral (under) surface (hypospadias) or dorsal surface (epispadias) of the penis rather than at the tip.
Acquired disorders
Inflammatory disorders
Many inflammatory skin conditions can occur in the penis, foreskin and scrotum, such as eczema, psoriasis and lichen planus. In addition, more specific inflammatory diseases may cause penile (skin) inflammation.
Granuloma inguinale
Granuloma inguinale is caused by the Gram-negative bacillus Calymmatobacterium granulomatis. This is an STD and causes an ulcer on the glans.
Lymphogranuloma venereum
Lymphogranuloma venereum is an STD caused by Chlamydia trachomatis (which also causes non-specific urethritis). Males may be asymptomatic carriers of the organism. The infection causes a spontaneously healing red papule on the penis. Enlarged lymph nodes in the groin then develop, which then become soft and attach to the overlying skin. Sinus formation occurs.
Syphilis (caused by the spirochaete, Treponema pallidum), herpes simplex and human papilloma virus (HPV) are all important causes of penile infection (see Table 41).
| Infection | Organism | Clinical features |
|---|---|---|
| Syphilis | Treponema pallidum (bacterium, spirochaete) | Rare Penis usually involved in primary syphilis (‘chancre’ seen – nodule on penis). Heals after about 1month Penis can be involved in secondary syphilis (papular rash) |
| Herpes simplex | Herpes simplex virus (herpes virus) | Common Painful recurrent blisters/ulcers on penile skin May last 2–3weeks then resolve Virus can remain latent in sacral sensory ganglia and reactivate/recur |
| Human papilloma virus | Human papilloma virus (HPV; papillomavirus) | Causes condylomata acuminata (‘venereal warts’) Especially types 6 and 11 Types 16 and 18 can cause premalignant and malignant conditions |
| Chancroid | Haemophilus ducreyi | Rare Penile ulceration and inguinal lymphadenopathy |
Peyronie’s disease is a penile disease of unknown cause in which the penis becomes excessively curved or bowed due to accumulation of scar tissue (the curvature may make sexual intercourse impossible).
Tumours
The penis can be affected by both in situ and invasive (squamous) malignancies. Benign tumours of the penis are rare.
Intra-epithelial neoplasia
Unfortunately, there are three very confusing historical names for intra-epithelial dysplasia in the region of the penis and scrotum (see Table 42).
| On glans | On shaft | Glans + shaft |
|---|---|---|
| Erythroplasia of Queyrat | Bowen’s disease | Bowenoid papulosis |
| Red patches | Pale, thickened areas | Velvety papules (younger men) HPV-associated in most cases |
Squamous cell carcinoma
This is a relatively rare tumour in Western countries (and very rare in circumcised males), but occur more frequently in parts of Asia and Africa. A poorly retracting infected foreskin and infected glans are probably risk factors. There is an association between HPV 16 and 18 infection and squamous cell carcinoma. The tumour may vary from a papillary and well-differentiated malignancy with abundant keratin formation to a solid, ulcerated, widely invasive, poorly differentiated lesion (which spreads via lymphatics to local lymph nodes).
22.2. The prostate
The prostate is a 20g, walnut-shaped gland located in the male perineum. The exact function of the gland is still unclear. The gland lies subjacent to the bladder and is traversed by the urethra. Any enlargement of the prostate gland, particularly that part surrounding the urethra (see Figure 60 for zones of the prostate), can lead to reduction/obstruction of flow of urine –dribbling, hesitancy, poor stream or complete blockage (retention). The prostate is composed of glandular and fibromuscular components, and it is hyperplasia/hypertrophy of both of these elements and malignancy of the glandular elements that commonly lead to urinary symptoms.
 |
| Figure 60 |
Hyperplasia of the prostate
This is such a common finding in adult men that it is often considered to be a normal part of ageing (probably about 80% of 80-year-olds will have evidence of prostatic hyperplasia). The prostate has a nodular, whorled appearance to the naked eye (nodular hyperplasia). It is mainly the periurethral and transition zones that are affected. Down the microscope, the glandular and/or stromal components may be affected. The glands may become papillary in form, or cystically dilated. However, hyperplastic glands have two cell layers – an inner clear cell layer and an outer, more darkly staining, basal cell layer. Hyperplasia of the prostate is often accompanied by areas of infarction, chronic inflammation and glandular atrophy.
Acute and chronic prostatitis can also occur in the setting of urinary tract infection (UTI) with organisms such as Escherichia coli, Pseudomonas and Klebsiella.
Carcinoma of the prostate
Carcinoma of the prostate is a very common malignancy. The biological behaviour of this tumour is poorly understood – a significant number of latent and incidental cancers are found at autopsy or in tissue removed at operation on an apparently benign prostate (e.g. transurethral resection of the prostate, TURP). Thus, it is likely that some prostatic cancers either never progress or only do so very slowly. The disease is more common in older men (particularly those aged over 60) and is seen more often in black men than in white men or Asian men. A small number of prostatic cancers appear familial. Most cases (about 70%) arise in the peripheral zone of the prostate.
Macroscopically, it is usually difficult to see prostatic cancer (it may or may not cause gland enlargement). On microscopy, prostatic cancer is usually an adenocarcinoma (although leiomyosarcoma and lymphoma occur, and rhabdomyosarcoma may be seen in children; Table 43). The Gleason grading system is now widely used for prostatic adenocarcinoma. This system depends on the glandular differentiation and pattern of infiltration of the tumour (see Table 44).
| Incidence | Age >50years (very common in >80-year-olds) |
| Risk factors | Black men > white men > Asians + family history ?fats in diet ?androgen-driven |
| Associated lesions | High-grade PIN (particularly multifocal) |
| Clinical presentation | Incidental finding Urinary symptoms |
| Diagnosis | Per rectal examination, ultrasound scan and biopsy Blood levels of prostatic-specific antigen (PSA) |
| Macroscopic | Usually invisible to the naked eye |
| Microscopic | Gleason scoring system (see Table 44) |
| Pattern of spread | Local versus lymphatic versus blood |
| Treatment | Carefully supervised ‘watch and wait’ (small intraprostatic lesions) Surgery Radiotherapy |
| Gleason grade (or pattern) | Characteristics |
|---|---|
| 1 | Uncommon Very round, regular, monotonous, closely packed glands Well circumscribed |
| 2 | Similar to 1, but less circumscribed, some variation in gland size and shape |
| 3 | Commonest grade May be small or large glands or cribriform (sieve-like) pattern May be marked variation in size/shape of glands Ragged edges and infiltrates widely |
| 4 | Glands now fused together Nests and streams of cells seen |
| 5 | Large sheets of malignant cells Necrosis may be seen May be very undifferentiated |
The higher the Gleason score (achieved by adding together the commonest two patterns or doubling a single pattern tumour) the more poorly differentiated the tumour. There is a correlation between the score of the tumour and its biological behaviour (the higher the score, the higher the cancer mortality rate). The tumour may be associated with high-grade prostatic intra-epithelial neoplasia (PIN; thought to be a likely precursor lesion). Adenocarcinoma of the prostate typically invades locally through the gland and into surrounding pelvic tissues and then by lymphatics to local/regional lymph nodes. Prostatic cancer has a propensity to metastasise via the bloodstream to bones (particularly the spine).
22.3. The testis and epididymis
The testis
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