Clinical and endocrinological evaluation of patients with congenital microphallus

Multidisciplinary approach and management of patients who seek medical advice for penile size concerns: a narrative review

We aimed to provide an overview of the strategies available to manage patients concerned about their penile size and to provide useful surgical hints regarding the most common penile enlargement approaches, based on our surgical expertise in this field. A comprehensive research was carried out on MEDLINE/PubMed database to identify pertinent studies concerning penile enlargement issues. The search strategy included a range of keywords; e.g. penis, penile, enlargement, augmentation, lengthening, girth. Management of penile size-related concerns represents a real challenge for the urologist, especially when dealing with patients suffering from penile dysmorphophobic disorder (PDD). A multidisciplinary preoperative assessment, including a psychiatric/psychological evaluation, may help in discerning those patients who would benefit the most from counselling/conservative management from those who would benefit from surgery instead. Conservative approaches include the use of vacuum-based and penile-stretching devices, which have shown encouraging levels of efficacy and safety. Over the last decades, different surgical strategies have been developed, aimed at either increasing flaccid penile length or improving penile girth. Penile lengthening procedures are more established, and satisfactory results can be achieved by experienced, large referrals' volume, surgeons. To date, there is lack of consensus regarding the penile girth enhancing techniques, and therefore these should be regarded as experimental. A multidisciplinary approach is necessary to identify patients with PDD, who should not be offered surgical intervention and should be referred for psychiatric/psychological counselling instead. The surgical approach should be tailored to the subject's unique anatomy and underlying conditions.

Micropenis: etiology, diagnosis and treatment approaches

Micropenis is a medical diagnosis based on correct measurement of length. If stretched penile length is below the value corresponding to - 2.5 standard deviation of the mean in a patient with normal internal and external male genitalia, a diagnosis of micropenis is considered. Micropenis can be caused by a variety of factors including structural or hormonal defects of the hypothalamic-pituitary-gonadal axis. It can also be a component of a number of congenital syndromes. For the etiological evaluation, endocrinologic tests are important. This article reviews the etiology, diagnosis, treatment and management of micropenis.

REVIEWS: Are Androgens Critical for Penile Erections in Humans? Examining the Clinical and Preclinical Evidence

Androgens are deemed critical for penile-tissue development, growth, and maintenance of erectile function, however, their role in erection, especially in humans, remains controversial. In this review, we summarize information from clinical and animal model studies to provide a comprehensive and rational argument for the role of androgens, or lack thereof, on penile erection ability in humans. The goal of this review is to present the clinical and preclinical evidence available in the literature with regard to testosterone and erectile physiology and engage the reader in this discussion. Ultimately, each reader will have to form his or her own conclusions based on the existing evidence. In humans, androgen-deficiency manifestations are noted in clinical situations such as: (i) inadequate development of the penis; and (ii) loss of erectile function in prostate cancer and benign prostatic hyperplasia patients managed with medical or surgical castration or antiandrogen therapy. Androgen treatment causes: (i) improvement in sexual function in hypogonadal patients treated with androgen supplementation; (ii) improvement in nocturnal penile tumescence in hypogonadal patients treated with androgens; (iii) improvement in erectile function with androgen supplementation in patients who did not respond to phosphodiesterase type 5 inhibitor therapy initially; and (iv) improvement in the well-being, mood, energy, and sexual function in aging men who have testosterone deficiency treated with androgen therapy. In contrast to animals, especially rodents in which the adrenal cortex does not synthesize androgens, the human adrenal is a source of peripherally circulating androgen precursors, thus, complete androgen insufficiency may not be observed in men at a younger age. Furthermore, in light of the concept that a threshold of androgen levels exists in animals and humans below which sexual function is diminished, further contributes to the complexity of understanding androgens role in erections, especially in humans. Nevertheless, based on the preclinical and clinical data available in the literature, to date, we infer that androgens play a critical role in maintaining erectile physiology in humans.

The child with micropenis

Micropenis refers to an extremely small penis with a stretched penile length of less than 2.5 SD below the mean for age or stage of sexual development. It should be differentiated from a buried or hidden penis and aphallia. It is important to use a standard technique of stretched penile measurement and nomograms for age to identify children with micropenis. All children above 1 year of age with a stretched penile length of less than 1.9 cm need evaluation. Based on etiology they can be classified as hypogonadotropic hypogonadism (hypothalamic or pituitary failure), hypergonadotropic hypogonadism (testicular failure), partial androgen insensitivity syndrome and idiopathic groups. The help of a pediatric endocrinologist, geneticist, pediatric surgeon and/or urologist is often necessary. Growth velocity is an important determinant of associated hypothalamic or pituitary pathology. GnRH and/or hCG stimulation tests are often helpful in evaluating the etiology. Similarly chromosomal studies are indicated in a few. Often the diagnosis is inferred by the presence of clinical features suggestive of a syndrome usually associated with hypogonadotropic hypogonadism. Irrespective of the underlying cause a short course of testosterone should be tried in patients with micropenis and an assessment of the penis to respond should be made. Transdermal DHT has also been reported to be effective in prepubertal children. Children with hypopituitarism and GH deficiency respond to appropriate hormonal therapy. Surgical correction is not indicated in the common endocrine types of micropenis. Many studies have shown that most testosterone treated children have satisfactory gain in length of penis and sexual function. Thus sexual reassignment is done very infrequently now.

Androgen induction of DNA synthesis in the rat penis

OBJECTIVES

The androgen sensitivity of the mammalian penis has long been appreciated. However, the precise biochemical and structural sequelae of alterations in testosterone, and the mechanisms thereof, remain to be elucidated. Recently, the androgen dependence of rat penile erectile tissue was further clarified at our institution, where the induction of apoptosis was demonstrated in response to castration. In continuity, we report the results of a follow-up study of the regenerative capacity of the regressed, castrated rat penile erectile tissue when testosterone is replenished.

METHODS

Three groups of rats were used: normal control rats, castrated without testosterone replenishment, and castrated with subsequent testosterone replenishment. In the third group, castrated rats were given testosterone and killed at 24-hour intervals over 4 days. Specimens of the penis, small bowel, and prostate were obtained from all animal groups. Immunohistochemical identification of intraperitoneally administered 5-bromo-2'-deoxyuridine, a thymidine analogue, was performed to detect new DNA synthesis. The incorporation of this molecule into high molecular weight nuclear DNA served as a measure of DNA synthesis and, hence, cellular proliferation.

RESULTS

Testosterone-replenished castrated rat penile stromal cells, both cavernosal and spongiosal, showed more enhanced proliferative activity than those of both castrated unreplenished and uncastrated control rats. Trichrome staining permitted the differentiation of responsive cell subsets. Various cell types were found to respond to replenished testosterone, including myocytes, fibrocytes, endothelial cells, and Schwann cells. Pronounced DNA synthesis occurred as early as 48 hours after the replenishment of testosterone. For purposes of technique validation, sections of small bowel were examined, in which glandular crypt cells would be expected to show rapid turnover. The nuclei of these bowel sections stained in all animal groups throughout the experiment, thus validating the staining technique. The technique of castration and testosterone replenishment was validated by confirming the known response of rat ventral prostate to androgen withdrawal and replenishment.

CONCLUSIONS

Our findings provide evidence that testosterone induces cellular proliferation and new DNA synthesis in the penile erectile tissue of castrated rats. This response to testosterone is not limited to one cell type, but rather is multicellular.

The effects of testosterone on the cavernous tissue and erectile function

A review of the current literature is conducted to explore the developmental aspects, animal and human experiences and the effects of pharmacological manipulation to explain the role androgens play in sexual function with special emphasis on erectile function and the erectile tissue. This review reveals that androgens are necessary for the normal development of the penis and their deficiency results in significant structural abnormalities. Although androgen receptors in the penis decrease after puberty, they usually do not disappear completely. Animal data show that androgens support erectile function through a direct effect on the erectile tissue. Experimental castration results in impaired erectile response to central and peripheral stimulation and decrease in penile tissue concentration of nitric oxide synthase-containing nerves. Testosterone replacement reverses these abnormalities. In the rat penis, apoptosis is induced by castration and new DNA synthesis is induced by testosterone replenishment. Human data are less clear than animal data. Castration results in loss of libido and in erectile dysfunction. However, these effects are not universal. Testosterone enhances libido, frequency of sexual acts and sleep-related erections. Its effects on erotic erections are not clear.

Microphallus: eventual phallic size is dependent on the timing of androgen administration

Micropenis secondary to hypogonadotropic hypogonadism in the Sprague-Dawley rat was induced by either injection of supraphysiological doses of dihydrotestosterone to the timed pregnant dam on gestational days 16 and 17 or by long acting microspheres of the gonadotropic agonist, leuprolide acetate. Following the induction of micropenis the animals were treated with dihydrotestosterone beginning at either day 7, 28, 56 or 84 of life. Within the study populations all animals treated with dihydrotestosterone had phallic enlargement greater than untreated controls (p < 0.01). However, animals beginning treatment on day 7 or 28 had persistent microphallus (p < 0.01). In contrast, if hormonal therapy was initiated on day 56 or 84 the phallus became normal in length. Immunohistological studies for androgen receptor expression revealed that early androgen exposure accelerated the loss of androgen receptor protein from the penis during growth. These data suggest that prepubertal exposure of the penis to androgens may significantly reduce the eventual penile size of the hypogonadotropic hypogonadal micropenis.

Audiological, vestibular and radiological abnormalities in Kallman's syndrome

Kallman's syndrome is a multifaceted congenital disorder with predominantly endocrine abnormalities. We have characterized the associated mixed hearing loss and identified consistent radiological evidence of abnormal temporal bone anatomy. Abnormal labyrinthine morphology is accompanied by a complete absence of response to vestibular stimulation with caloric or rotational chair testing. The endocrine abnormalities are correctable and Kallman's syndrome is a diagnosis worthy of consideration when assessing children with congenital hearing loss.

Androgen binding activity in the spongy tissue of mammalian penis

The binding of [3H]R1881 to cytosol fractions was determined for the spongy tissues of horse, porcine and human penis. Binding of [3H]R1881 to cytosol fractions from these spongy tissues was found to be specific with high affinities (mean of Kd; 1.8 X 10(-10) M) but with equally low binding capacities (mean of 4.66 fmol/mg. protein). Saturation analysis revealed that the binding capacity was similar for both corpus cavernosum and corpus spongiosum of horse penis. We conclude that a trace amount of androgen receptor is present in spongy tissue of the penis and that there is no difference in cytosolic receptors between corpus cavernosum and corpus spongiosum in adult mammalian penis.

Diagnostic approach to the newborn with ambiguous genitalia

When assessing an infant with ambiguous genitalia, there are some important points to remember: Do not delay the evaluation of a patient with ambiguous genitalia. A delay may expose the patient unnecessarily to a life-threatening situation, such as a salt-losing crisis associated with 21-hydroxylase deficiency or one of the testosterone biosynthetic defects. Also, it is unfair to expect the family to be able to deal emotionally with the uncertainty of unresolved gender assignment. Never perform a buccal smear. There is absolutely no indication for performing a buccal smear at any point in the evaluation of any patient with ambiguous genitalia. Use of a buccal smear to determine gender assignment was helpful decades ago, before analysis of human chromosomes was possible. With current cytogenetic methodologies that can detect chromosomal mosaicism and subtle abnormalities of the X and Y chromosomes, there is never an indication to perform a buccal smear. Never make a gender assignment on the basis of the appearance of the external genitalia alone. The chromosomal sex and gonadal sex need to be determined first. The parents' feelings regarding the desired sex of the child, gender identity and fertility need to be discussed. Once there are sufficient data, gender assignment can be made. Gender assignment should be made as soon as possible after birth, but absolutely should be made by 18 months of age, when children develop gender identity. Never equivocate in the assignment of gender. The parents and the physicians must be absolutely certain of the gender assignment and must view their decision as final. Follow-up visits with the family ideally include an assessment of their acceptance of the gender assignment of the child. If there is ambivalence, steps must be taken to identify the source of ambivalence and to clarify the issues.

Cryptorchidism: isolated and associated with other genitourinary defects

Cryptorchidism is the most common disorder of sexual differentiation in male children, with an incidence of 3.4 per cent in the term newborn, decreasing to 0.8 per cent at 1 year of age. The mechanisms of normal testicular descent are multifactorial and include an intact hypothalamic-pituitary-testicular axis, as well as a normal gubernaculum and epididymis. In boys with cryptorchidism, the testes demonstrate degenerative changes histologically as early as 1 to 2 years of age. Both testes may be affected, even with a unilateral undescended testis. The most important long-term complications of cryptorchidism include infertility and testicular cancer. The risk of malignancy is approximately 40 times higher in male subjects with cryptorchidism than in normal men, and is highest in male subjects who have had an intra-abdominal testis and in certain intersex conditions. Orchiopexy does not appear to lessen this risk. Hormonal therapy with HCG or LH-RH has remained unproven in clinical trials in the United States; therefore, orchiopexy remains standard treatment. HCG is recommended if the clinician suspects that a testis is retractile, however. Orchiopexy should be performed between 12 and 18 months of age to prevent the degenerative changes that are demonstrable by 2 years.

Changes in amount and intracellular distribution of androgen receptor in human foreskin as a function of age

To provide insight into the factors that control growth of the penis we measured the amount and intracellular distribution of specific high affinity androgen receptor in foreskins obtained at circumcision from 49 males varying in age from newborn to 59 yr. Total (cytosolic plus nuclear extract) androgen receptor decreased from approximately 40 fmol/g tissue weight in newborn foreskins to approximately 25 fmol/g by 1 yr of age. The amount of receptor rose in childhood to approximately 180 fmol/g in the late teenage years and fell thereafter to approximately 20-40 fmol/g in men older than 40 yr. The amount of receptor in the nuclear fraction increased at the time of puberty and subsequently decreased in parallel with the decline in total receptor level. These changes in androgen-receptor amount are similar when expressed per milligram DNA or per milligram protein.

Elevation of serum gonadotropins establishes the diagnosis of anorchism in prepubertal boys with bilateral cryptorchidism

Of more than 500 boys with bilateral cryptorchidism who presented during a 10-year period 28 prepubertal patients less than 11 years old who had no palpable testes after human chorionic gonadotropin therapy were studied to assess the ability of serum gonadotropin levels to identify patients with anorchism. Of the boys 21 had a normal testosterone response to human chorionic gonadotropin therapy and all of them had testes at exploration. The serum luteinizing hormone levels ranged from 2 to 6 mIU per ml., with a mean of 3.7 mIU per ml., and the serum follicle-stimulating hormone levels ranged from 1.6 to 6.2 mIU per ml., with a mean of 3.7 mIU per ml. Seven patients showed no testosterone response to human chorionic gonadotropin and all but 1 underwent exploration, at which time no testes were found. Of these 7 patients 6 had elevated gonadotropin levels that averaged 3 standard deviations above the mean. For comparison, 2 pubertal patients with nonpalpable gonads and 3 castrated prepubertal boys also were studied. From the study we concluded that in boys with nonpalpable gonads 1) abnormally elevated serum gonadotropin levels before puberty are indicative of anorchism, 2) neither exploration nor human chorionic gonadotropin stimulation tests are essential for diagnosis in these select patients, 3) serum gonadotropin levels alone are not sufficient for a definitive diagnosis after puberty and 4) all boys with normal serum gonadotropin levels must undergo exploration regardless of the outcome of a human chorionic gonadotropin stimulation test.

Embryonic testicular regression syndrome: variable phenotypic expression in siblings

Two 46,XY agonadal siblings with variable degrees of sexual ambiguity are described. The eldest child is a phenotypic male with micropenis. The younger patient, a phenotypic female with slight fusion of the genital folds and absent müllerian ducts, conforms to the criteria usually accepted for the diagnosis of true agonadism. Coexistence of anorchia and true agonadism in the same sibship supports the hypothesis, suggested by others, that both disorders are related and are due to the regression of the embryonic testes.

Microphallus: distinction between anomalous and endocrine types

Operative treatment of microphallus has been proscribed in recent reports. It is not indicated for the more common endocrine type because of deficient gonadotropin, primary testicular disorder or end-organ defect. However, an operation may be quite necessary for the other form owing to defective morphogenesis--the anomalous type. Representative cases provide evidence that the method of treatment depends on the type of microphallus.

Early determination of androgen-responsiveness is important in the management of microphallus

Of fourteen boys with microphallus who were studied consecutively, nine had hypopituitarism that might otherwise have not been recognised. All fourteen were treated with low-dose, intramuscular testosterone enanthate administered in one or two 3-month courses. In each case, penile size was increased into the normal range without evoking either a significant increase in height velocity or an advancement of skeletal maturation. Before considering surgical sex reversal in infants and young children with microphallus, it is essential to assess whether treatment with intramuscular testosterone will induce clinically significant growth of the microphallus.

The phenotypic expression of selective disorders of male sexual differentiation

Normal male sexual differentiation is the result of a series of individual steps that occur in an orderly fashion: testicular differentiation, müllerian regression, wolffian duct development, differentiation of the urogenital sinus and external genitalia, phallic growth and descent of the testes. Herein we present the pathophysiological mechanism by which selective disorders disrupt these normal events and produce specific phenotypes.