Phimosis

Etiology

Physiological Phimosis

At birth, the prepuce is non-retractile and remains so for a variable length of time. First appearing in the eighth week of gestation as an epithelial ridge, by 16 weeks of gestation the prepuce is complete and encases the glans. At this stage, the epithelial lining of the glans and prepuce are contiguous, and these preputial adhesions are essentially a normal developmental process. Separation begins proximally by the process of desquamation with small spaces forming, which eventually coalesce to form the preputial sac.

Pathological Phimosis 

The pathological process gives characteristic stenosis scarring and pallor of the preputial opening. It is typically caused by balanitis xerotica obliterans (BXO). BXO is a cicatrizing skin condition histologically identical to lichen sclerosis. It is a chronic skin condition with some evidence suggesting an autoimmune etiology. There has been controversy regarding BXO as a precipitant for penile cancer later in life.

Epidemiology

The natural history of non-retractile foreskin and preputial adhesions was extensively documented in the mid-twentieth century, firstly by Gairdner in 1949 and then Oster in 1968. Their combined studies show that in all but a small proportion of boys the foreskin will be retractile once the boys mature into their teenage years. These studies demonstrated that phimosis is present in 8% of 6- to 7-year-olds, 6% of 10- to 11-year-olds and 1% of 16- to 17-year-old boys. By contrast, preputial adhesions remain much more common throughout childhood and adolescence, but by 17-years of age, only 3% will have persisting adhesions. [1],[2]

VTrue pathological phimosis caused by BXO has a relatively stable incidence across all decades of life, with a spike in the third decade of life. Relatively rare in children under the age of 5, there is a peak childhood incidence between 9 and 11 years of age, with 0.6% of boys affected by years of age. Modern studies are questioning this doctrine, reporting varied incidence from 5% to 52% and children younger than 5 years as having BXO. [3]

Pathophysiology

In physiological phimosis, attempted retraction of the foreskin results in an apparent constriction ring a few millimeters proximal to the preputial orifice. The orifice on retraction has been described as akin to a flower, with a moist supple and unscarred appearance with pouting of the inner mucosa. 

In contrast, BXO has a sclerotic constricting band 1 to 2 cm proximal to the distal end, and there may be glans involvement in a diffuse pattern with whitish discoloration of the peri-meatal area and an erythematous area being pathognomonic. [4]

Histopathology

BXO has the following characteristic histological features: hyperkeratosis with follicular plugging, atrophy of the stratum spongiosum with hydropic degermation of basal cells, hyalinosis, and a band-like chronic inflammatory cell infiltrate with the homogenization of collagen. [4]

History and Physical

In physiological phimosis, ballooning of the foreskin is a common presentation in childhood when the foreskin is still non-retractile. Typically occurring between 2 to 4 years of age, it is a self-limiting phenomenon that resolves once the foreskin becomes more retractile. Parents can be reassured that this does not have any effect on the child’s bladder or ability to void. [5]

BXO has an insidious onset; there may be associated irritation, local infection, dysuria, bleeding before atrophy phimosis, and meatal stenosis. The disease can also have a cyclical course with periods of remission. On rare occasions, patients can present with acute urinary retention or nocturnal enuresis from chronic outflow obstruction.

Evaluation

Laboratory tests and radiography are not typically required in the assessment of phimosis, and studies have demonstrated no evidence of obstruction from physiological phimosis. [5]

Pathological phimosis treated with surgery should have any surgically excised skin sent for histology to confirm the diagnosis and exclude any evidence of malignancy.

Treatment / Management

Treatment of physiological phimosis is not indicated, and reassurance and an explanation of the natural history of the healthy non-retractile foreskin should be given to concerned parents. Circumcision is the preferred treatment for pathological phimosis and represents the only absolute indication for this procedure in children.

Alternatives to circumcision are not suitable to treat phimosis due to BXO but are designed to achieve a fully retractile foreskin. These treatments can be particularly useful with patients experiencing balanoposthitis. Topical steroids have been extensively studied, and topical application to the foreskin can render it retractable at an earlier stage. A typical treatment course is 4 to 8 weeks, with regular attempts at retraction during this time. Given the low risk associated with short duration topical steroid use, this can be repeated if necessary. [6],[7](A1)

An alternative surgical approach to circumcision is the preputioplasty; this approach allows preservation of the foreskin. Initially, postoperative appearances are similar to a dorsal slit procedure, but with regular retraction of the foreskin following the procedure, this resolves into a normal retractile prepuce. [8],[9]

Differential Diagnosis

Acute balanoposthitis is a purulent, pyogenic infection of the prepuce and represents the most severe form of posthitis. These conditions lead to erythema and edema of the prepuce. Dysuria is common, and minor bleeding may occur. These episodes typically resolve with antibiotic treatment and require no further intervention unless recurrent episodes occur.

Paraphimosis is related to manipulation of the foreskin with failure to reduce the foreskin to its natural position. Presentation with pain and edema of both the prepuce and the glans is typical. Paraphimosis does not represent a disease process, and single episodes, once resolved, warrant no surgical intervention. Recurrent episodes are unusual and are an indication for circumcision.

Congenital megaprepuce is a rare condition. On examination, the outer preputial skin directly meets the abdominal wall dorsally, the scrotum ventrally with an absence of penile shaft skin. Micturition is always abnormal with the entire preputial sac filling with urine. This can be expressed to leave a more normal appearance. This condition must be treated with a modified circumcision; any attempt to treat this condition with a standard circumcision will result in the requirement for revision surgery complicated by the loss of outer preputial skin.

Preputial adhesions are a normal physiological feature and resolve spontaneously over time [1]. Surgical intervention plays a very minor role except in severe cases.