Faculty of Medicine, Universitatea de Medicină, Farmacie, Științe și Tehnologie George Emil Palade din Târgu Mureș

Pathology of the Male Reproductive System

Overview of the Male Reproductive System

The male reproductive system is responsible for various critical functions:

  • Producing male gametes (sperm).
  • Secreting male sex hormones, particularly testosterone.
  • Maturing, storing, and transporting sperm.
  • Achieving reproductive functions and ensuring male fertility.

The normal functioning of this system relies heavily on:

  • The structural integrity of the genital organs.
  • The neuroendocrine regulation of the hypothalamic-pituitary-testicular axis, which involves:
      - GnRH (Gonadotropin-Releasing Hormone) stimulating the pituitary gland.
      - FSH (Follicle-Stimulating Hormone) promoting spermatogenesis in Sertoli cells.
      - LH (Luteinizing Hormone) stimulating testosterone production in Leydig cells.
      - Testosterone exerting negative feedback on the hypothalamus and pituitary gland.
Physiopathological Importance

Any disturbance concerning:

  • Embryonic development of the testicles.
  • The positioning of the testes.
  • Hormonal or spermatogenic function.
    These disturbances may lead to:
  • Hypogonadism.
  • Infertility.
  • Disorders in sexual development.

Relevant examples of pathologies within the male reproductive system include:

  • Cryptorchidism: A defect in testicular descent.
  • Klinefelter syndrome: A chromosomal disorder associated with testicular insufficiency.

Male Hypogonadism

Definition of Male Hypogonadism

Male hypogonadism is characterized by insufficient testicular function, marked by inadequate testosterone production and/or impaired spermatogenesis. This condition may arise from:

  • Primary testicular dysfunction.
  • Impairment of the hypothalamic-pituitary axis.
Etiology of Male Hypogonadism

  1. Primary (testicular) causes: Direct impact on testicles.
       - Congenital issues:
         - Chromosomal abnormalities (e.g., Klinefelter syndrome - 47,XXY).
         - Testicular dysgenesis.
         - Untreated bilateral cryptorchidism.
         - Anorchia (absence of testes).
       - Acquired conditions:
         - Orchitis (such as mumps).
         - Testicular trauma.
         - Testicular torsion.
         - Radiotherapy or chemotherapy effects.
         - Testicular tumors.
         - Testicular autoimmune diseases.

  2. Secondary (hypogonadotropic) causes: Dysfunction within the hypothalamic–pituitary axis.
       - Congenital conditions:
         - Kallmann syndrome.
         - Congenital GnRH deficiency.
       - Acquired conditions:
         - Pituitary or hypothalamic tumors.
         - Surgical intervention or irradiation of the pituitary gland.
         - Hyperprolactinemia.
         - Traumatic brain injury.
         - Infiltrative diseases like sarcoidosis or hemochromatosis.

  3. Functional and metabolic causes:
       - Obesity.
       - Diabetes mellitus.
       - Metabolic syndrome.
       - Decrease in SHBG (Sex Hormone-Binding Globulin).

  4. Medicinal and toxic causes:
       - Chronic use of opioids.
       - Abuse of anabolic steroids.
       - High doses of glucocorticoids.
       - Chronic alcoholism.

Prolactinoma

Definition of Prolactinoma

Prolactinoma is a benign pituitary adenoma emerging from the lactotrope cells of the adenohypophysis, identified by autonomous hypersecretion of prolactin (PRL). In males, hyperprolactinemia often leads to:

  • Functional hypogonadotropic hypogonadism, a significant endocrine cause of male infertility.
  • Male infertility is defined as the inability of a male to impregnate a partner after one year of regular, unprotected intercourse, in the absence of a discernible female cause.
  • Clinically andrologically, male infertility indicates a quantitative and/or qualitative alteration in spermatogenesis, sperm function, or abnormalities in ejaculation and semen transport mechanisms.
Etiology of Prolactinoma
  1. Primary causes:
       - Lactotropic adenoma:
         - Microprolactinoma: Less than 10 mm.
         - Macroprolactinoma: 10 mm or larger.
       - Most are sporadic, but some may be associated with MEN1 (multiple endocrine neoplasia type 1).
  2. Secondary causes:
       - Antidopaminergic drugs (antipsychotics, metoclopramide).
       - Primary hypothyroidism leading to elevated TRH.
       - Chronic renal failure.
       - Compression of the pituitary stalk, leading to a "stalk section" effect.
Pathophysiological Mechanism of Prolactinoma
  1. Loss of dopaminergic control due to monoclonal lactotropic proliferation resulting in autonomous PRL secretion, independent of dopamine regulation.
  2. Systemic hyperprolactinemia affects:
       - Inhibition of pulsatile GnRH secretion, disrupting the hypothalamic-pituitary-gonadal axis.
       - Low levels of LH and FSH lead to decreased stimulation of Leydig and Sertoli cells, resulting in:
         - Decreased total and free testosterone.
         - Impaired spermatogenesis.
         - A reduction in inhibin B levels, also causing infertility manifested as oligozoospermia or azoospermia and impaired sperm motility.
  3. Additional effects of PRL include direct interference with androgen receptors, leading to erectile dysfunction related to reduced testosterone.
  4. In cases of macroprolactinoma, the mass effect may cause:
       - Compression of the optic chiasm, resulting in bitemporal hemianopsia.
       - Headaches.
       - Associated hypopituitarism, leading to decreased ACTH, TSH, and GH levels.
Clinical Presentation of Prolactinoma

A. Symptoms of hypogonadism:
   - Decreased libido.
   - Erectile dysfunction.
   - Infertility.
   - Reduced muscle mass.
   - Osteopenia or osteoporosis.

B. Reproductive signs:
   - Oligospermia or azoospermia.
   - Normal or slightly reduced testicular volume.

C. Rare manifestations:
   - Gynecomastia.
   - Galactorrhea, which is rare in men.

D. Neurological manifestations (in cases of macroadenoma):
   - Headaches.
   - Visual field impairments.

Diagnosis of Prolactinoma

Diagnosis involves:

  1. Hormonal profile showcasing:
       - Elevated PRL levels, frequently exceeding 200 ng/mL in macroprolactinoma cases.
       - Reduced total testosterone levels.
       - Low or inadequately normal LH and FSH.
       - Exclusion criteria for thyroid dysfunction (TSH for hypothyroidism) and renal failure (creatinine levels).
  2. Imaging studies:
       - Pituitary MRI with contrast medium.
  3. Assessment of infertility through sperm analysis (spermogram).
Treatment of Prolactinoma

Treatment options include:

  1. First line: Dopaminergic agonists (e.g., cabergoline and bromocriptine).
  2. Surgical intervention: Indicated in cases of:
       - Resistance or intolerance to dopaminergic agonists.
       - Severe optic chiasm compression.
       - Acute pituitary apoplexy.
  3. Radiotherapy: Rarely indicated for aggressive prolactinomas or tumors that resist both drug and surgical treatments.

Klinefelter Syndrome

Definition of Klinefelter Syndrome

Klinefelter syndrome is a genetic chromosomal disorder characterized by one or more extra X chromosomes in males. It results in the loss of Leydig cells and seminiferous tubule dysgenesis. It is strictly a genetic etiology arising from numerical abnormalities of the sex chromosomes due to errors during cell division, with an occurrence rate of approximately 1 in 1,000 men. The most common karyotype associated with this syndrome is 47,XXY, while other forms include:

  • Mosaicism: 46,XY, 47,XXY.
  • Rare forms: 48,XXXY, 48,XXYY, 49,XXXXY.

The disease manifests through:

  • Impaired spermatogenesis.
  • Insufficient testosterone secretion.
  • Disorders in male sexual development.
Main Pathophysiological Mechanisms

  1. Primary genetic anomaly:
       - Errors in the separation of sex chromosomes (nondisjunction) during maternal or paternal meiosis leading to a gamete with two X chromosomes. After fertilization, the resulting embryo may carry a karyotype of 47,XXY or mosaicism (46,XY/47,XXY).
       - Excessive genetic material from the X chromosome disrupts the expression of genes essential for testicular development and impairs the differentiation of male gonads.

  2. Impaired testicular development:
       - Testes appear normal at birth but undergo progressive degeneration of seminiferous tubules, loss of germ cells, and fibrosis or hyalinization, culminating in primary testicular failure during childhood or puberty.

  3. Impaired spermatogenesis:
       - The destruction of seminiferous tubules results in azoospermia—commonly seen—or severe oligozoospermia in mosaic forms. Infertility results as an early and significant outcome of this condition.

  4. Testicular endocrine dysfunction:
       - Initially hyperplastic Leydig cells transition to being functionally inadequate, leading to diminished testosterone secretion.

  5. Disruption of the hypothalamic-pituitary-testicular axis:
       - Decreased testosterone levels result in the loss of negative feedback on the pituitary gland, prompting it to increase levels of LH and FSH, ultimately causing hypergonadotropic hypogonadism.

Secondary Pathophysiological Mechanisms

  • Androgen–estrogen imbalance:
       - Residual androgens are converted into estrogens, a process facilitated by adipose tissue, leading to a low androgen to estrogen ratio. This results in gynecomastia and gynoid fat distribution.

  • Decreased inhibin B:
       - Caused by Sertoli cell destruction leading to unrestricted FSH elevation, indicating the extent of spermatogenesis impairment.

  • Secondary metabolic effects:
       - Low testosterone levels contribute to decreased muscle mass, increased fat mass, and insulin resistance. Additionally, testosterone deficiency intensifies the risk of developing osteoporosis and metabolic syndrome.

Diagnosis and Clinical Picture
  • If Klinefelter syndrome is not detected via amniocentesis, only 10% of cases are diagnosed before puberty.
  • Early manifestations include cryptorchidism, behavioral issues, learning problems, and tall stature.
  • Most patients experience normal pubertal development.
  • However, manifestations during adolescence can include gynecomastia, microorchidism, poorly developed muscle mass, disproportionately long limbs due to lack of epiphyseal fusion, narrow shoulders, and wide hips.
  • In adulthood, one of the most common symptoms is infertility, accompanied by small, firm testicles, gynecomastia, and signs of androgen deficiency.
  • Individuals may also have a heightened risk for diabetes mellitus, breast cancer, pulmonary emphysema, and bronchiectasis that is independent of testosterone deficiency.
Treatment of Klinefelter Syndrome

Management primarily involves androgen replacement therapy for those with testosterone deficiency. Many patients possess testosterone levels at or below the lower limit of normal.
Regarding abnormalities in the seminiferous tubules and associated infertility, no definitive therapeutic options currently exist, although advancements in reproductive technology, including microsurgical extraction of sperm from the testis (microTESE, microdissection testicular sperm extraction), offer potential solutions for affected individuals.