Etiology
Penile lesions can be categorized by cause ( Box 76-1 ).
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Trauma
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Blunt trauma
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Penetrating or sharp trauma
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Acute bending accident
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Tumors
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Inflammation
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Infections
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Erectile dysfunction
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Impotence
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Priapism
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Postoperative penis
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Idiopathic
Penile Trauma
Penile fracture is usually caused by the exertion of axial forces on the erect penis, causing a tear of the tunica albuginea, resulting in subcutaneous extrusion of blood. This injury usually occurs during vigorous sexual intercourse. Self-inflicted injury by forceful downward bending of the erect penis to achieve detumescence, direct blunt trauma to the erect penis, and bite injuries are other causes of penile injury.
Blunt trauma to the flaccid penis usually does not cause penile fracture but may cause an extratunical or cavernosal hematoma. Intracavernosal hematomas also may occur in long-distance cyclists.
Penile Malignancy
The irritative effect of smegma in uncircumcised men is presumed to be an important cause of penile squamous cell carcinoma (SCC). Human papillomavirus types 16 and 18 are also reported in association with penile SCC. Chronic inflammation or urethral stricture may result in anterior urethral carcinoma.
Benign Palpable Masses
Cowper’s duct syringocele results from the cystic dilatation of the main duct of the bulbourethral gland of Cowper. Penile hemangiomas and penile root neurofibromas are the other benign neoplasms of the penis.
Peyronie’s Disease
The cause of Peyronie’s disease is unknown and possibly multifactorial. The disease results in chronic inflammation, which leads to fibrosis and focal thickening of the tunica albuginea.
Erectile Dysfunction
Impotence is discussed in Chapter 75 .
Priapism
Priapism can be divided into low-flow and high-flow subtypes. Venous, low-flow, ischemic priapism is due to vascular stasis and decreased penile venous outflow. Causes include sickle cell disease or trait, other blood dyscrasias, neurologic abnormalities such as syphilis, brain tumors, brain and spinal cord injury, trauma, medication for erectile dysfunction (particularly if administered intracavernosally), other drugs such as antidepressants, and illicit drugs (particularly cocaine). Arterial, high-flow, nonischemic priapism is caused by perineal or penile blunt trauma with direct cavernosal artery injury and resultant formation of an arterial-lacunar fistula. It also may be caused by intracavernosal injections.
Prevalence and Epidemiology
Penile trauma is fairly uncommon but important because of its relative urologic emergency. Penile fracture is defined as rupture of a corpus cavernosum and its surrounding fibroelastic sheath, the tunica albuginea. Typically, a tear occurs in only one of the corpora cavernosa and its surrounding tunica albuginea; however, corpus spongiosum and urethral involvement may occur in approximately 20% of penile fractures.
SCC is the most common penile malignancy. It usually arises in the glans but also may arise in the urethra. Other urethral malignancies include transitional cell carcinoma and adenocarcinoma. Penile sarcomas are uncommon. Penile SCC is one of the most commonly seen malignancies in Asia and Africa but is rare in the United States, where African-American men are affected twice as often as white men. In children, rhabdomyosarcoma is the most common malignant tumor of the lower genitourinary tract, including the penis.
Peyronie’s disease is uncommon, accounting for 0.3% to 0.7% of all urologic disorders. It occurs most often in the fourth to sixth decades of life and occasionally in men younger than 20 years of age.
Impotence is common and is discussed in Chapter 75 . Priapism can be arterial/high flow (nonischemic) or venous/low flow (ischemic). Low-flow priapism is a urologic emergency.
Prevalence and Epidemiology
Penile trauma is fairly uncommon but important because of its relative urologic emergency. Penile fracture is defined as rupture of a corpus cavernosum and its surrounding fibroelastic sheath, the tunica albuginea. Typically, a tear occurs in only one of the corpora cavernosa and its surrounding tunica albuginea; however, corpus spongiosum and urethral involvement may occur in approximately 20% of penile fractures.
SCC is the most common penile malignancy. It usually arises in the glans but also may arise in the urethra. Other urethral malignancies include transitional cell carcinoma and adenocarcinoma. Penile sarcomas are uncommon. Penile SCC is one of the most commonly seen malignancies in Asia and Africa but is rare in the United States, where African-American men are affected twice as often as white men. In children, rhabdomyosarcoma is the most common malignant tumor of the lower genitourinary tract, including the penis.
Peyronie’s disease is uncommon, accounting for 0.3% to 0.7% of all urologic disorders. It occurs most often in the fourth to sixth decades of life and occasionally in men younger than 20 years of age.
Impotence is common and is discussed in Chapter 75 . Priapism can be arterial/high flow (nonischemic) or venous/low flow (ischemic). Low-flow priapism is a urologic emergency.
Clinical Presentation
Most cases of penile fracture have a typical clinical history. The patient reports hearing a cracking or popping sound and experiences a sharp pain followed by rapid detumescence, swelling, ecchymosis, deformity, and deviation of the penis to the side opposite the injury. Patients with spongiosal and urethral injury may present with inability to urinate, hematuria, dysuria, and extravasation of urine and/or urethrorrhagia.
SCC typically begins as focal thickening or ulceration of the glans. Urethral carcinomas manifest with urinary complaints.
Cowper’s duct syringocele may manifest as postvoid dribbling, urinary frequency, weak stream, or hematuria.
Peyronie’s disease may result in painful induration or plaques along the penis. It may cause penile deformity in erection and difficulty during sexual intercourse.
In patients with low-flow priapism, the penis is fully erect and painful. This is a urologic emergency. Patients with high-flow priapism usually develop a painless partial erection and are able to increase rigidity with sexual stimulation. Because the clinical presentation of high-flow priapism is not as dramatic as that of the low-flow type, it is occasionally recognized days or even months after the onset of symptoms. Treatment of high-flow priapism is not an emergency because the risk for vascular damage with irreversible impotence is low. However, reduced potency may result in patients with long-standing untreated disease.
Pathology
Penile fractures usually occur in the proximal shaft or midshaft. Rupture of the corpus cavernosum usually occurs in a transverse plane, in the ventral portion of the corpus cavernosum, and typically involves less than half of the circumference of the erectile body.
Penile SCC most commonly arises in the glans. Urethral carcinomas in males mostly arise in the bulbous and membranous portions of the urethra, followed by the fossa navicularis.
Trauma
The thickness of the tunica albuginea decreases from 2 mm to 0.5 to 0.25 mm during erection. External force applied to erect penile tissue causes a sudden rise in intracorporeal pressure, resulting in further distention and strain of the already thinned tunica albuginea, thereby causing a tear. Spongiosal and urethral injuries are associated with a higher rate of complications.
Cavernosal hematomas may result from injury to the subtunical venous plexus or smooth muscle trabeculae in the absence of complete tunical disruption. Intracavernosal hematomas are usually bilateral, resulting from injury to the cavernosal tissue when the base of the penile shaft is crushed against the pelvic bones.
Vascular Injuries
Rupture of the dorsal penile vessels may mimic penile fracture, but deformation and immediate detumescence do not occur because of the intact tunica albuginea. The hematoma may be superficial or deep to Buck’s fascia depending on the site of vascular injury. Thrombosis of the superficial and deep dorsal penile veins is a rare urologic emergency, and the clinical and ultrasonographic appearance can mimic penile fracture.
A cavernous arterial-lacunar fistula may develop after perineal or penile trauma, leading to high-flow priapism.
Malignancy
Localized SCC (without cavernosal invasion or spread to lymph nodes) has a 3-year survival of 93%. This rate decreases markedly once there is spread of disease beyond the superficial layers of the penis.
Leiomyosarcoma may arise from the smooth muscle of the glans or one of the corpora cavernosa. Leiomyosarcomas metastasize very early if arising from a corpus cavernosum. Rhabdomyosarcomas are usually very aggressive.
Penile lymphoma is an extremely rare neoplasm. It is usually secondary to retrograde hematogenous or lymphatic spread or direct extension from a neighboring organ. The most commonly affected site is the penile shaft, followed by the glans. Diffuse large cell lymphoma is the most common histologic subtype. Staging of penile tumors is described in Table 76-1 .
| Stage | Characteristics |
|---|---|
| I | Tumor localized to the glans penis |
| II | Tumor invading the corpora without nodal or distant metastases |
| III | Tumor involving the corpora and local lymph nodes |
| IV | Distant metastases |
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