Cryptorchidism and Male Infertility

Cryptorchidism

Undescended testis, arrest along descent path. ~0.2% adult males. Location: 70% inguinal ring, 25% abdominal, 5% elsewhere.

Etiology (mostly unknown): mechanical (short cord, narrow canal, adhesions), genetic (trisomy 13, scrotal/cremaster maldevelopment), hormonal (deficient androgen).

Morphology: 80% unilateral, 20% bilateral. Gross: small, firm, fibrotic.

Micro (atrophy begins ~AGE 2, contrary to old belief):

Seminiferous tubules: progressive germ cell loss (only spermatogonia/spermatids; spermatogenesis persists in only 10%), thickened BM. Advanced: hyalinised tubules, Sertoli cells only, prominent BM
Interstitial stroma: ↑fibrovascular stroma, conspicuous Leydig cells (relative prominence from tubular atrophy, not true Leydig proliferation)

Clinical: asymptomatic, found on exam only. Untreated beyond ~2yr/puberty:

Sterility (bilateral)/infertility (unilateral)
Inguinal hernia — frequently coexists
Malignancy — 30-50x ↑risk (mostly seminoma, embryonal carcinoma). Intra-abdominal > inguinal risk — NOT necessarily more oncogenic, just detected LATER (not palpable)

Male infertility (3-tier classification)

Same atrophy pattern as cryptorchidism, various causes:

A. Pre-testicular: hypopituitarism (tumour/trauma/infarction/cyst); oestrogen excess (cirrhosis, adrenal tumour, Sertoli/Leydig tumour, or exogenous — prostate Ca treatment); glucocorticoid excess (Cushing’s, or exogenous — UC/asthma/RA treatment); hypothyroidism, diabetes (hypospermatogenesis)

B. Testicular: agonadism, cryptorchidism, maturation arrest, hypospermatogenesis, Sertoli cell-only syndrome, Klinefelter syndrome (XXY — hypogonadism, azoospermia, gynaecomastia, eunuchoid build, ↓IQ), mumps orchitis, irradiation damage

C. Post-testicular: congenital block (vas deferens absence/atresia), acquired block (gonorrhoea, surgery), impaired motility with normal count (immotile cilia syndrome)

Clinical relevance

3-tier classification (pre-testicular/testicular/post-testicular) mirrors same anatomic-level reasoning as other endocrine/obstructive disorders — directs workup toward hormone axis, biopsy, or ductal imaging by tier, not “infertility” as one problem. Intra-abdominal>inguinal malignancy risk = DETECTION TIMING not different oncogenic environment — reminder that apparent risk differences between anatomic variants of same condition can reflect surveillance bias, not true biology. Conspicuous Leydig cells = RELATIVE finding (tubular atrophy makes them stand out), not true proliferation — why hormone production/secondary sexual characteristics preserved despite lost fertility. Orchiopexy timing (~age 2) determines whether malignancy/infertility risk reducible — why cryptorchidism treated as near-emergency paediatric surgery, not elective/deferrable.

Cryptorchidism

Cryptorchidism (undescended testis) is arrest of testicular descent at some point along its normal path. Incidence ~0.2% of adult males. Location: 70% inguinal ring, 25% abdominal, 5% elsewhere along the descent path.

Etiology

Mostly unknown, but implicated factors:

Mechanical — short spermatic cord, narrow inguinal canal, peritoneal adhesions.
Genetic — trisomy 13, scrotal/cremaster muscle maldevelopment.
Hormonal — deficient androgen secretion.

Morphology

Unilateral in 80%, bilateral in 20%. Gross: small, firm, fibrotic testis.

Micro — contrary to older belief, atrophic changes begin by ~age 2:

Seminiferous tubules: progressive germ cell loss (tubules lined only by spermatogonia/spermatids; spermatogenesis foci persist in only 10%); thickened tubular basement membrane; advanced cases show hyalinised tubules with only Sertoli cells and a prominent surrounding basement membrane.
Interstitial stroma: increased fibrovascular stroma with conspicuous Leydig cells (single or small clusters) — a relative prominence that reflects the disproportionate loss of tubular tissue rather than true Leydig cell hyperplasia.

Clinical Features

Asymptomatic — found only on examination. Untreated beyond ~age 2 (or certainly beyond puberty), significant risks follow:

Sterility/infertility — bilateral disease → sterility; unilateral → infertility.
Inguinal hernia — frequently coexists.
Malignancy — 30–50× increased risk of testicular cancer (most commonly seminoma and embryonal carcinoma) compared to normally descended testes. Risk is higher for intra-abdominal than inguinal-canal testes — not necessarily because the intra-abdominal position is more oncogenic per se, but because an inguinal-canal tumour is detected earlier (palpable), while an intra-abdominal one grows silently longer before diagnosis.

Male Infertility

The same testicular atrophy pattern seen in cryptorchidism can result from a range of causes, classified by anatomic level:

A. Pre-Testicular Causes

Hypopituitarism — tumour, trauma, infarction, cyst.
Oestrogen excess — endogenous (hepatic cirrhosis, adrenal tumour, Sertoli/Leydig cell tumour) or exogenous (prostate cancer treatment).
Glucocorticoid excess — endogenous (Cushing’s syndrome) or exogenous (treatment of ulcerative colitis, asthma, RA).
Other endocrine disorders — hypothyroidism, diabetes mellitus (both associated with hypospermatogenesis).

B. Testicular Causes

Agonadism — total testicular absence.
Cryptorchidism (as above).
Maturation arrest — spermatogenesis fails beyond an immature stage.
Hypospermatogenesis — all maturation stages present, but in reduced numbers.
Sertoli cell-only syndrome — congenital/acquired absence of all germ cells; tubules lined by Sertoli cells alone.
Klinefelter syndrome — XXY intersex state: primary hypogonadism, azoospermia, gynaecomastia, eunuchoid build, subnormal intelligence.
Mumps orchitis — complicating parotitis.
Irradiation damage — permanent germ cell destruction.

C. Post-Testicular Causes

Congenital block — vas deferens absence/atresia.
Acquired block — gonorrhoea, surgical injury.
Impaired sperm motility with normal counts — e.g. immotile cilia syndrome.

Clinical Relevance

The three-tier classification of male infertility (pre-testicular/testicular/post-testicular) mirrors the same anatomic-level reasoning used for other endocrine and obstructive disorders elsewhere in pathology — it directs the diagnostic workup toward hormone axis testing, testicular biopsy, or anatomic/ductal imaging depending on which tier is suspected, rather than treating “infertility” as one undifferentiated problem.
The greater malignancy risk in intra-abdominal versus inguinal cryptorchid testes being explained by detection timing rather than a fundamentally different oncogenic environment is a useful reminder that apparent differences in “risk” between anatomic variants of the same underlying condition can sometimes reflect surveillance/detection bias rather than true biological differences — worth holding as a genuine possibility whenever comparing risk across anatomically distinct but pathogenetically similar presentations.
The conspicuous Leydig cells seen in cryptorchid testis histology are a relative, not absolute, finding — they stand out because the surrounding tubular tissue has atrophied, not because Leydig cells have genuinely proliferated, which is why hormone production (testosterone, secondary sexual characteristics) is typically preserved in cryptorchidism even as fertility is lost.
Recognising that orchiopexy timing (by ~age 2) is what determines whether malignancy and infertility risk can be meaningfully reduced explains why cryptorchidism is treated as a paediatric surgical emergency of sorts rather than an elective, deferrable procedure — the testicular atrophy process is already underway by the time a delayed correction would occur.