Originally Posted by
Merc.
OTHER DISEASES
Other disease states have also resulted in gynecomastia.
Men with end stage renal disease may have reduced testosterone, and elevated gonadotropins. This apparent primary testicular failure may then lead to increased breast development (18).
The gynecomastia of liver disease, particularly cirrhosis, does not have a clear etiology. Some have speculated that the gynecomastia is the result of estrogen overproduction, possibly secondary to increased extraglandular aromatization of androstenedione, which may have decreased hepatic clearance in cirrhotics. However, testosterone administration to cirrhotics causes a rise in estradiol, but decreases the prevalence of gynecomastia (13, 3, 37). Therefore, although the association of gynecomastia with liver disease is apparent, current data are conflicting and the mechanism by which this occurs remains unclear.
As previously stated, thyrotoxicosis is associated with gynecomastia. Patients often have elevated estrogen that may result from a stimulatory effect of thyroid hormone on peripheral aromatase. Testosterone may also be increased possibly due to thyroid-hormone-stimulated increase in SHBG, as free testosterone is usually normal. Since SHBG binds testosterone more avidly than estradiol, there is a higher ratio of free estradiol to free testosterone. Thus, with normal testosterone and increased estrogen, there is an elevated estrogen to testosterone ratio. In addition, LH is also increased, which may also stimulate testicular estrogen synthesis (18, 10).
Gynecomastia can also follow spinal cord disorders. Most patients with spinal cord disorders display depressed testosterone levels and, in fact, can develop testicular atrophy with resultant hypogonadism and infertility. Some have speculated that this may result from recurrent urinary tract infections, increased scrotal temperature, and a neuropathic bladder, which ultimately cause acquired primary testicular failure. The exact mechanism, however, remains elusive (19).
Refeeding gynecomastia refers to breast development in men recovering from a malnourished state (15). Although most cases regress within seven months, the etiology of this phenomenon has not been fully elucidated.
HIV patients can also develop gynecomastia. There is a high incidence of androgen deficiency due to multifactorial causes, including primary and secondary hypogonadism (30).
DRUGS
A significant percentage of gynecomastia is caused by medications or exogenous chemicals that result in increased estrogen effect. This may occur by several mechanisms: 1) they possess intrinsic estrogen-like properties, 2) they increase endogenous estrogen production, or 3) they supply an excess of an estrogen precursor (e.g. testosterone or androstenedione) which can be aromatized to estrogen. Examples of drugs that cause gynecomastia are listed in Tables 2 and 3. Contact with estrogen vaginal creams, for instance, can elevate circulating estrogen levels. These may or may not be detected by standard estrogenic qualitative assays. An estrogen-containing embalming cream has been reported to cause gynecomastia in morticians (4, 14). Recreational use of marijuana, a phytoestrogen, has also been associated with gynecomastia. It has been suggested that digitalis causes gynecomastia due to its ability to bind to estrogen receptors (18, 39). The appearance of gynecomastia has been described in body builders and athletes after the administration of aromatizable androgens. The gynecomastia was presumably caused by an excess of circulating estrogens due to the conversion of androgens to estrogen by peripheral aromatase enzymes (9).
Drugs and chemicals that cause decreased testosterone levels either by causing direct testicular damage, by blocking testosterone synthesis, or by blocking androgen action can produce gynecomastia. For instance, phenothrin, a chemical component in delousing agents, possessing antiandrogenic activity, has been attributed as the cause of an epidemic of gynaecomastia among Haitian refugees in US detention centers in 1981 and 1982 (8). Chemotherapeutic drugs, such as alkylating agents, cause Leydig cell and germ cell damage, resulting in primary hypogonadism. Flutamide, an anti-androgen used as treatment for prostate cancer, blocks androgen action in peripheral tissues, while cimetidine blocks androgen receptors. Ketoconazole, on the other hand, can inhibit steroidogenic enzymes required for testosterone synthesis. Spironolactone causes gynecomastia by several mechanisms. Like ketoconazole, it can block androgen production by inhibiting enzymes in the testosterone synthetic pathway (i.e. 17a hydroxylase and 17-20-desmolase), but it can also block receptor-binding of testosterone and dihydrotestosterone (45). In addition to decreasing testosterone levels and biologic effects, spironolactone also displaces estradiol from SHBG, increasing free estrogen levels. Ethanol increases the estrogen to androgen ratio and induces gynecomastia by multiple mechanisms as well. Firstly, it is associated with increased SHBG, which decreases free testosterone levels. Secondly, it increases hepatic clearance of testosterone, and thirdly, it has a direct toxic effect on the testes themselves (30). Unfortunately, besides the drugs stated, a multitude of others cause gynecomastia by unknown mechanisms (Table 3).
Table 2. Drugs that induce gynecomastia by known mechanisms
Estrogen-
like, or binds to estrogen receptor Stimulate estrogen synthesis Supply aromatizable estrogen precursors Direct Testicular Damage Block testosterone synthesis Block androgen action Displace estrogen from SHBG
Estrogen vaginal cream Gonado-
tropins Exogenous androgen Busulfan Ketoconazole Flutamide Spironol-
actone
Estrogen-
containing embalming cream Growth Hormone Androgen precursors (ie androstene-
dione and DHEA) Nitrosurea Spironol-
actone Bicalut-
amide Ethanol
Delousing powder Vincristine Metronidazole Finasteride
Digitalis Ethanol Etomidate Cyproterone
Clomiphene Zanoterone
Marijuana Cimetidine
Ranitidine
Spironol-
actone
Table 3. Drugs that cause gynecomastia by uncertain mechanisms:
Cardiac and antihypertensive medications:
Calcium channel blockers (verapamil, nifedipine, diltiazem)
ACE Inhibitors (captopril, enalapril
b blockers
Amiodarone
Methyldopa
Reserpine
Nitrates
Psychoactive drugs:
Neuroleptics
Diazepam
Neuroleptics
Diazepam
Phenytoin
Tricyclic antidepressants
Haloperidol
Drugs for infectious diseases:
Indinavir
Isoniazid
Ethionamide
Griseofulvin
Drugs of Abuse:
amphetamines
Other:
Theophylline
Omeprazole
Auranofin
Diethylpropion
Domperidone
Penicillamine
Sulindac
Heparin
MALE BREAST CANCER
Male breast cancer is rare and comprises only 0.2 percent of all male cancers. Although uncommon, it has been associated with gynecomastia and necessitates inclusion in the differential diagnosis. Other risks include Klinefelter's syndrome, exogenous estrogen exposure, family history, and testicular disorders. It is unclear if these are specific risks for breast cancer are linked to the stimulatory process responsible for gynecomastia. New evidence suggests obesity and consumption of red meat may also raise the risk for the development of male breast cancer (21).
PATIENT EVALUATION
HISTORY AND PHYSICAL EXAMINATION
At presentation, all patients require a thorough history and physical exam. Particular attention should be given to medications, drug and alcohol abuse, as well as other chemical exposures. Symptoms of underlying systemic illness, such as hyperthyroidism, liver disease, or renal failure should be sought. Furthermore, the clinician must recall neoplasm as a possible etiology and should establish the duration and timing of breast development. Obviously, rapid breast growth that has occurred recently is more concerning than chronic gynecomastia. Additionally, the clinician should inquire about fertility, erectile dysfunction and libido to rule out hypogonadism, either primary or secondary, as a potential cause.
In our experience, the breast examination is best performed with the patient supine and with the examiner palpating from the periphery to the areola. The glandular mass should be measured in diameter. Gynecomastia is diagnosed by finding subareolar breast tissue of 2 cm in diameter or greater. Malignancy is suspected if an immobile firm mass is found on physical examination. Skin dimpling, nipple retraction or discharge, and axillary lymphadenopathy further support malignancy as a possible diagnosis.
A thorough testicular exam is essential. Bilaterally small testes imply testicular failure, while asymmetric testes or a testicular mass suggest the possibility of neoplasm. Visual field impairment may suggest pituitary disease. Physical findings of underlying systemic conditions such as thyrotoxicosis, HIV disease, liver, or kidney failure should also be assessed.
LABORATORY EVALUATION
All patients who present with gynecomastia should have serum testosterone, estradiol, LH and b HCG measured. Further testing should be tailored according to the history, physical examination and the results of these initial tests. An elevated b HCG or a markedly elevated serum estradiol suggests neoplasm and a testicular ultrasound is warranted to identify a testicular tumor, keeping in mind, however, that other non-testicular tumors can also secrete b HCG. A low testosterone level, with an elevated LH and normal to high estrogen level indicates primary hypogonadism. If the history suggests Klinefelter's Syndrome, then a karyotype should be performed for definitive diagnosis. Low testosterone, low LH and normal estradiol levels imply secondary hypogonadism, and hypothalamic or pituitary causes should be sought. If testosterone, LH and estradiol levels are all elevated, then the diagnosis of androgen resistance should be entertained. Liver, kidney and thyroid function should be assessed if the physical examination suggests liver failure, kidney failure, or hyperthyroidism, respectively. Furthermore, if examination of breast tissue suggests malignancy, a biopsy should be performed. This is of particular importance in patients with Klinefelter's syndrome, who have an increased risk of breast cancer.
TREATMENT
Treatment of the underlying endocrinologic or systemic disease that has caused gynecomastia is mandatory. Testicular tumors, such as Leydig cell, Sertoli cell or granulosa cell tumors should be surgically removed. In addition to surgery, germ cell tumors are further managed with chemotherapy involving cisplatin, bleomycin and either vinblastine or etoposide (38, 16). Should underlying thyrotoxicosis, renal or hepatic failure be discovered, appropriate therapy should be initiated. Medications that cause gynecomastia should also be discontinued whenever possible based on their role in management of the underlying condition. Of course, if a breast biopsy indicates malignancy, then mastectomy should be performed.
If no pathologic abnormality is detected, then appropriate treatment is close observation. A careful breast exam should be done initially every 3 months until the gynecomastia regresses or stabilizes, after which a breast exam can be performed yearly. It is important to remember that some cases of gynecomastia, especially that which occurs in pubertal boys, can resolve spontaneously.
MEDICAL TREATMENT
If the gynecomastia is severe, does not resolve, and does not have a treatable underlying cause, some medical therapies may be attempted. There are 3 classes of medical treatment for gynecomastia: androgens (testosterone, dihydrotestosterone, danazol), anti-estrogens (clomiphene citrate, tamoxifen) and aromatase inhibitors such as testolactone. Testosterone treatment of hypogonadal men with gynecomastia often fails to produce breast regression once gynecomastia is established. Unfortunately, testosterone treatment may actually produce the side effect of gynecomastia by being aromatized to estradiol. Thus, although testosterone is used to treat hypogonadism, its use to specifically counteract gynecomastia is limited (47). Dihydrotestosterone, a non-aromatizable androgen, has been used in patients with prolonged pubertal gynecomastia with good response rates (24). Since dihydrotestosterone is given either intramuscularly or percutaneously, this may restrict its usefulness. Danazol, a weak androgen that inhibits gonadotropin secretion, resulting in decreased serum testosterone levels, has been studied in a prospective placebo-controlled trial, whereby gynecomastia resolved in 23 percent of the patients, as opposed to 12 percent of the patients on placebo (22). Unfortunately, undesirable side effects including edema, acne, and cramps have limited its use (30). Investigators have reported a 64 percent response rate with 100 mg/day of clomiphene citrate, a weak estrogen and moderate antiestrogen (26). Lower doses of clomiphene have shown varied results, indicating that higher doses may need to be administered, if clomiphene is to be attempted. Tamoxifen, also an antiestrogen, has been studied in 2 randomized, double-blind studies in which a statistically significant regression in breast size was achieved, although complete regression was not documented (1). One study compared tamoxifen with danazol in the treatment of gynecomastia. Although patients taking tamoxifen had a greater response with complete resolution in 78 percent of patients treated with tamoxifen, as compared to only a 40 percent response in the danazol-treated group, the relapse rate was higher for the tamoxifen group (46). Although complete breast regression may not be achieved and a chance of recurrence exists with therapy, tamoxifen, due to relatively lower side effect profile, may be a more reasonable choice when compared to the other therapies. If used, tamoxifen should be given at a dose of 10 mg twice a day for at least 3 months (30). An aromatase inhibitor, testolactone, has also been studied in an uncontrolled trial with promising effects (51). Further studies must be performed on this drug before any recommendations can be established on its usefulness in the treatment of gynecomastia. Newer aromatase inhibitors such as anastrozole and letrozole may have therapeutic potential but no study has been published to confirm its efficacy in treatment of gynecomastia. (32)
SURGICAL TREATMENT
When medical therapy is ineffective, particularly in cases of longstanding gynecomastia, or when the gynecomastia interferes with the patient's activities of daily living, or when there is suspicion of malignancy of breast, then surgical therapy is appropriate. This includes removal of glandular tissue coupled with liposuction, if needed. In our experience, uses of delicate cosmetic surgical techniques are warranted to prevent unsightly scarring.
PREVENTION OF GYNECOMASTIA IN MEN WITH PROSTATE CANCER
Because androgen deprivation is one of the commonly used treatment modalities for advanced prostate cancer, its possible role in the development of gynecomastia is of particular concern to clinicians. Low dose prophylactic irradiation has been variably reported to reduce the rate of gynecomastia in men receiving estrogens or antiandrogens for advanced prostate cancer (11) (48).
SUMMARY
In summary, gynecomastia is a relatively common disorder. The causes of its development range vastly from benign physiologic processes to rare neoplasms. Thus, in order to properly diagnose the etiology of the gynecomastia, the clinician must understand the hormonal factors involved in breast development. Parallel to female breast development, estrogen, along with GH and IGF-1 is required for breast growth in males. Since a balance exists between estrogen and androgens in males, any disease state or medication that can increase circulating estrogen or decrease circulating androgen, causing an elevation in the estrogen to androgen ratio, can induce gynecomastia. Due to the diversity of possibly etiologies, including neoplasm, performing a careful history and physical is imperative. Once gynecomastia has been diagnosed, treatment of the underlying cause is warranted. If no underlying cause is discovered, then close observation is appropriate. If the gynecomastia is severe, however, medical therapy can be attempted and if ineffective, glandular tissue can be removed surgically
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