Testicular Atrophy

Definition and Normal Background

Causes

1. Vascular / Ischemic

• Testicular torsion - twisting of the spermatic cord obstructs venous drainage while arteries remain patent, causing hemorrhagic infarction. Even after successful orchiopexy, atrophy occurs in ~27% of patients who had torsion, especially those presenting >10 hours after onset or whose testis did not bleed on deep medullary incision. - Hinman's Atlas of Urologic Surgery, p. 2269
• Progressive atherosclerosis in old age - gradual reduction in blood supply
• Trauma - even without testicular rupture, late-onset atrophy has been documented. Blunt scrotal trauma can cause unilateral atrophy appearing months later. - Grainger & Allison, p. 4080

2. Cryptorchidism (Undescended Testis)

3. Inflammatory / Infectious

• Epididymo-orchitis (bacterial, most common): infection reaches the testis via the vas deferens or spermatic cord lymphatics. Fibrous scarring after resolution can cause atrophy. Leydig cells are usually spared, so androgen production is relatively preserved. - Robbins Pathologic Basis of Disease
• Mumps orchitis: occurs in 20-30% of postpubertal males with mumps (rare in children); acute interstitial orchitis develops ~1 week after parotitis. Sterility is a rare but recognized complication.
• Tuberculosis: the most common cause of testicular granulomatous inflammation; typically begins as epididymitis with secondary testicular involvement
• HIV/AIDS: testicular atrophy is a frequent autopsy finding. The etiology is multifactorial - fever, chronic illness, cachexia, cytokine activation, and direct cytotoxic effects of HIV. Patients with BMI <20 are 3.5x more likely to develop atrophy. Disseminated CMV infection is associated with a fivefold increased incidence. - Campbell-Walsh Urology, p. 2891

4. Endocrine / Genetic

• Klinefelter syndrome (47,XXY): the prototype primary testicular failure. Testicular atrophy with hyalinisation of seminiferous tubules and hypergonadotropic hypogonadism are the hallmarks. - Forensic Medicine & Toxicology; Robbins & Kumar Basic Pathology
• Hypopituitarism: loss of LH/FSH support leads to secondary atrophy
• Exhaustion atrophy: paradoxically, persistent stimulation by high levels of FSH can exhaust the tubular epithelium

5. Toxic / Iatrogenic

• Irradiation: highly toxic to spermatogonia; dose-dependent
• Antiandrogen therapy (e.g., for prostate carcinoma): suppression of testosterone leads to atrophy
• Cirrhosis and alcohol:
  • Cirrhosis elevates sex hormone-binding globulin, shifting the hormone balance toward estrogens ("feminization syndrome")
  • Alcohol has direct toxic effects on Leydig cells and suppresses the hypothalamic-pituitary-gonadal axis (decreased LH, decreased responsiveness to GnRH)
  • Spironolactone (commonly used in cirrhosis) displaces androgen from receptors and increases estradiol production
  • Sleisenger & Fordtran's GI & Liver Disease, p. 1825

6. Varicocele

7. Surgical Injury

• Inguinal herniorrhaphy: ischemic orchitis occurs in ~1% of primary hernioplasties but is significantly more common after re-do repairs. Damage to the pampiniform plexus (rather than the testicular artery itself) is the most common mechanism. Deliberate testicular artery ligation carries a ~14% risk of frank atrophy. - Schwartz's Principles of Surgery; Mulholland & Greenfield's Surgery

8. General / Systemic

• Generalized malnutrition or cachexia - any cause
• Aging - part of the normal aging process (physiological atrophy)

Concise Summary of Causes (Robbins Classification)

Histopathology

• Thickening and hyalinisation of the tubular basement membrane
• Loss of spermatogonia and other germ cells
• Increased interstitial (peritubular) fibrosis and stroma
• Relative prominence of Leydig cells (which are usually spared unless severe)
• In extreme cases: complete "vanishing testis" syndrome
• Robbins Pathologic Basis of Disease

Clinical Consequences

1. Infertility - loss of spermatogonia impairs or eliminates spermatogenesis
2. Hypogonadism - if Leydig cells are also affected, testosterone deficiency leads to decreased libido, erectile dysfunction, fatigue, loss of muscle mass, and osteoporosis
3. Increased cancer risk - atrophic and cryptorchid testes carry a significantly elevated risk of germ cell tumors (seminoma is the most common); this risk persists even in the contralateral testis and is not fully reversed by orchiopexy
4. Psychological impact - body image concerns

Imaging

Management Principles

• Treat the underlying cause where possible (e.g., early orchiopexy for cryptorchidism, prompt detorsion within 6 hours, varicocelectomy in adolescents with volume loss)
• Monitor for malignancy - regular self-examination; ultrasound surveillance in high-risk atrophic testes
• Hormone replacement - testosterone replacement therapy for symptomatic hypogonadism
• Fertility preservation - sperm banking before gonadotoxic therapy; microdissection testicular sperm extraction (micro-TESE) for azoospermia (notably, severe testicular atrophy does not preclude successful micro-TESE) - Campbell-Walsh Urology
• Post-torsion follow-up - close surveillance for atrophy after orchiopexy, especially with long duration of symptoms