PENIS DISORDERS

The penis may be affected by many congenital and acquired disorders. Only the most common malformations, inflammatory conditions, and neoplasms are considered here. Of the inflammatory disorders affecting the penis, a significant number represent STD.

Malformations

The most common malformations of the penis include abnormalities in the location of the distal urethral orifice, termed hypospadias and epispadias. Hypospadias, the more common of the two lesions, occurs in 1 in 250 live male births and designates an abnormal opening of the urethra along the ventral aspect of the penis. The urethral orifice, which may lie anywhere along the shaft of the penis, is sometimes constricted, resulting in urinary tract obstruction and an increased risk of urinary tract infections. The abnormality may be associated with other congenital anomalies, including inguinal hernias and undescended testes. The term epispadias indicates the presence of the urethral orifice on the dorsal aspect of the penis. Like hypospadias, epispadias may produce lower urinary tract obstruction; in other cases, the condition may result in urinary incontinence. Epispadias is commonly associated with bladder extrophy, a congenital malformation of the bladder.

Inflammatory Lesions

A significant number of inflammatory conditions of the penis are caused by STDs. Local inflammatory processes unrelated to STDs may also involve the penis. In addition, several other systemic inflammatory diseases may, on occasion, produce penile lesions.

The terms balanitis and balanoposthitis refer to local inflammation of the glans penis, or of the glans penis and the overlying prepuce, respectively. Most cases occur as a consequence of poor local hygiene in uncircumcised males, with accumulations of desquamated epithelial cells, sweat, and debris, termed smegma, acting as a local irritant. In such cases, the distal penis is typically red, swollen, and tender; a purulent discharge may be present.  Phimosis represents a condition in which the prepuce cannot be retracted easily over the glans penis. Although phimosis may occur as a congenital anomaly, most cases are acquired from scarring of the prepuce secondary to previous episodes of balanoposthitis. Regardless of its origin, most cases of phimosis are accompanied by evidence of ongoing distal penile inflammation. When a stenotic prepuce is forcibly retracted over the glans penis, the circulation to the glans may be compromised, with resultant congestion, swelling, and pain of the distal penis, a condition known as paraphimosis. Urinary retention may develop in severe cases.

Fungi may infect the skin of the penis and scrotum, because growth of fungi is favored by warm, moist conditions at this site and poor local hygiene. Genital candidiasis may occur in otherwise normal individuals, but it is particularly common in patients with diabetes mellitus. Candidiasis typically presents as an erosive, painful, intensely pruritic lesion involving the glans penis, scrotum, and adjacent intertriginous areas. Scrapings or biopsy specimens of the lesions reveal characteristic budding yeast forms and pseudohyphae within the superficial epidermis.

Neoplasms

More than 95% of penile neoplasms originate from squamous epithelium. In the United States, squamous cell carcinomas of the penis are relatively uncommon, accounting for about 0.4% of all cancers in males. In developing countries, however, penile carcinoma occurs at much higher rates. Most cases occur in uncircumcised patients older than 40 years of age. Several factors have been implicated in the pathogenesis of squamous cell carcinoma of the penis, including poor hygiene (with resultant exposure to potential carcinogens in smegma), smoking, and infection with human papillomavirus (HPV), particularly types 16 and 18.

As with squamous cell carcinomas at other sites, carcinomas of the penis are generally preceded by the appearance of malignant cells confined to the epidermis, termed intraepithelial neoplasia or carcinoma in situ. Three clinical variants of carcinoma in situ, all strongly associated with HPV infection, occur on the penis. Bowen disease occurs in older uncircumcised males and appears grossly as a solitary, plaquelike lesion on the shaft of the penis. Histologic examination reveals morphologically malignant cells throughout the epidermis with no invasion of the underlying stroma (Fig. 18-1). Bowen disease is not unique to the penis but may also occur elsewhere on the skin and on mucosal surfaces, including the vulva and oral mucosa. Its major clinical importance lies in the potential for progression to invasive squamous cell carcinoma, a complication estimated to occur in as many as 33% of cases involving the penis. When Bowen disease presents as an erythematous patch on the glans penis, it is called erythroplasia of Queyrat. Bowenoid papulosis occurs in young, sexually active males and is histologically identical to Bowen disease. Clinically, however, it presents with multiple reddish brown papules on the glans and is most often transient, with only rare progression to carcinoma in immunocompetent patients.