Porth's Essentials of Pathophysiology, 4e

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Genitourinary and Reproductive Function

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lesions arising on the prepuce or glans as a result of HPV infection (see Chapter 41). Most penile cancers are of squamous epithelial cell ori- gin and include carcinoma in situ, which is restricted to the epithelium and does not infiltrate the underlying der- mis, and invasive carcinomas. 14–16 In situ carcinomas of the penis are include Bowen disease and erythroplasia of Queyrat . 15 Bowen disease appears as a sharply demarcated, erythematous or grayish-white plaque on the shaft of the penis. Erythroplasia of Queyrat manifests as single or mul- tiple shiny red, sometimes velvety plaques on the glans or foreskin. In approximately 10% of men, these lesions may transform into infiltrating squamous cell cancer. 14,15 Invasive squamous cell carcinoma of the penis usually begins as a small lump or ulcer on the glans or inner sur- face of the prepuce. The lesions are usually slow growing and have often been present for a year or more before being brought to medical attention. The lesions are usu- ally nonpainful until they undergo secondary ulceration and infection. 14–16,22 If phimosis is present, there may be painful swelling, purulent drainage, or difficulty urinat- ing. Metastasis to the inguinal lymph node is character- istic of early-stage disease, but widespread dissemination is uncommon until the lesion is far advanced. Diagnosis usually is based on physical examination and biopsy results. Computed tomography scans, penile ultrasonographic studies, and magnetic resonance imaging (MRI) may be used in the diagnostic workup. Treatment options vary according to stage, size, location, and inva- siveness of the tumor. Carcinoma in situ may be treated conservatively with fluorouracil cream application or laser treatment. 22 Conservative treatment requires frequent follow-up examinations. Surgery remains the mainstay of treatment for invasive carcinoma. Disorders of the Scrotum andTestes The testes, or male gonads, are two egg-shaped struc- tures located outside the abdominal cavity in the scro- tum. Embryologically, they develop in the abdominal cavity and then descend through the inguinal canal into a pouch of peritoneum (which becomes the tunica vagi- nalis) in the scrotum during the seventh to ninth months of fetal life. 23 As they descend, the testes pull their arter- ies, veins, lymphatics, nerves, and conducting excretory ducts with them. These structures are encased by the cremaster muscle and layers of fascia that constitute the spermatic cord (Fig. 39-8A). The descent of the testes is thought to be mediated by testosterone, which is active during this stage of fetal development. After descent of the testes, the inguinal canal closes almost completely. Failure of this canal to close pre- disposes to the development of an inguinal hernia later in life (Fig. 39-8B). An inguinal hernia or “rupture” is a protrusion of the parietal peritoneum and part of the intestine through an abnormal opening from the abdominal cavity. A loop of small bowel may become incarcerated in an inguinal hernia (strangulated her- nia), in which case the lumen of the bowel may become obstructed and its vascular supply compromised.

Spermatic cord Testicular vessels Ductus deferens

Layers of tunica vaginalis Parietal Visceral

Testis

Skin Dartos muscle and fascia

Scrotum

A

Peritoneum

Skin

Loop of intestine

Testis

The testes and epididymis are completely surrounded by the tunica vaginalis, a serous pouch derived from the peritoneum during fetal descent of the testes into the scrotum. The tunica vaginalis has an outer parietal layer and a deeper visceral layer that adheres to the dense fibrous covering of the testes, the tunica albuginea. The tunica albuginea protects the testes and gives them their ovoid shape. A space exists between these two layers that typically contains a few milliliters of clear fluid. The cremaster muscles, which are bands of skeletal muscle arising from the internal oblique muscles of the trunk, elevate the testes. The testes receive their arterial blood supply from the long testicular arteries, which branch from the aorta. The testicular veins, which drain the testes, arise from a venous network called the pampi- niform plexus that surrounds the spermatic artery. The testes are innervated by fibers from both divisions of the autonomic nervous system. Associated sensory nerves B FIGURE 39-8. (A) Anterior view of the spermatic cord and inguinal canal and coverings of the spermatic cord and testes. (B) Indirect inguinal hernia. (Adapted from Moore KL, Agur AM. Essentials of Clinical Anatomy. 2nd ed. Philadelphia, PA: Lippincott Williams &Wilkins; 2002:130, 138.)