4.3 Testes and Penis

Question 1

Testis anatomy

Answer 1

Covered with tunica albuginea
250 pyramidal lobules, each containing 1-4 seminiferous tubules 30-70 cm long, converging at rete testis (at mediastinum)
Mediastinum testis: invagination of fibrous capsule on posterosuperior testis at insertion point of spermatic cord; corresponds to coalescence of seminiferous tubules from each testicular lobule, emerging as 12-20 efferent ductules

Question 2

Epididymis anatomy

Answer 2

Continuation of ductules at head (7-8 mm diameter) posterolaterally to testis, with body and tail continuing inferiorly to become vas

Question 3

MR signal of testis

Answer 3

Homogeneously intermediate on T1W and high on T2W

Question 4

Spermatic cord contents

Answer 4

Vas deferens, vessels, lymphatics (drain to lateral and preaortic nodes) and nerves

Question 5

Vas deferens course

Answer 5

Posterior aspect spermatic cord, diverges at deep inguinal ring, passing anterior to internal iliac artery, forming ejaculatory duct with seminal vesicle at prostatic base

Question 6

Neurovascular bundle in spermatic cord

Answer 6

Internal spermatic (tesicular - aorta), external spermatic (cremasteric - inferior epigastric) and differential arteries (to epididymis and vas - vesicular branch of internal iliac)
Pampiniform plexus drains to ipsilateral testicular vein
Nerves: cremasteric nerve, genital branch of genitofemoral nerve and testicular sympathetic plexus

Question 7

Scrotum anatomy

Answer 7

Wall derived from abdominal wall layers
Tunica vaginalis in continuity with peritoneal processus vaginalis; forms visceral and parietal layer
Dartos = vascular muscular wall of scrotum

Question 8

Embryological origin and path of testes

Answer 8

Genital ridges extend from T6 to S2
Coelomic epithelial cells form primitive sex cords, which become seminiferous tubules in presence of Y chromosome
Migrated germ cells from yolk sac walls via hindgut & dorsal mesenteric root form spermatogonia
Mesenchyme between seminferous tubules forms Leydig cells (begin to secrete testosterone at 8 weeks)
Mesonephric ducts form epididymis, vas deferens, seminal vesicles and ejaculatory ducts, while paramesonephric ducts regress
At 7-8 weeks, testes descend to pelvis, staying at deep inguinal ring until seventh month, then descend to scrotum

Question 9

Epididymitis - cause, imaging features

Answer 9

Commonest postpubertal acute scrotal pathology, likely ascending infection (gonococcal, E Coli, pseudomonas, TB); 20% develop orchitis
Acute US: Swollen hyperaemic (only sign in 20%) hypoechoic epididymis (>5 mm thick); Thickened scrotal skin ± hydrocoele (if complex suggests pyocoele)
Chronic US: Swollen epididymis ± hyperechoic

Question 10

Orchitis - cause, imaging, complication

Answer 10

Commonest complication of mumps infection in postpubertal males (in which case usually unilateral); causes unilateral atrophy in one third, bilateral in 10%; atrophy detectable by 6 months
US: Enlarged, hypoechoic (usually), hyperaemic testis; Focal orchitis does not distort testicular contour (unlike cancer)

Question 11

Varicocoele - definition, cause, location

Answer 11

Commonest treatable cause of male subfertility, L (95%) > R, 25% bilateral; if solitary on right - concern for RP malignancy
Abnormal dilatation pampiniform plexus, causing compressible scrotal veins > 2 mm diameter, more prominent on valsalva or standing
Due to incompetent valves of internal testicular vein, rarely due to obstruction

Question 12

Types of germ cell testicular cancer

Answer 12

[SpECT] - 95%; metastases may have different histology from original tumour
Seminomas (40%) - do not cause elevated AFP; homogenously hypoechoic, usually focal but may be diffuse, sharp interface with normal parenchyma; radiosensitive
Mixed (40%) - teratocarcinoma is commonest
Non-seminomatous GCT (more aggressive)
Embryonal Cell Carcinoma (10%) - cystic, heterogenous, ‘wild’
Teratoma (10%)
Choriocarcinoma (1%, aggressive, early haematogenous metastasis, frequently to brain)
Yolk sac carcinoma

Question 13

Types of Non-germ cell testicular cancer

Answer 13

5%; ‘sex cord’; usually benign
Leydig cell (can produce testosterone, 30% cause virilisation / feminisation)
Sertoli cell (can produce oestrogen and present with gynaecomastia)
Lymphoma (most common tumour in older men, may be bilateral) - less distinct margin
Metastases: Prostate, lung, kidney, GIT, myeloma, leukaemia

Question 14

Sentinel LNs of testicular cancer

Answer 14

Left - left renal perihilar group (just below left renal vein)
Right - paracaval LNs at or below right renal vein
Iliac and inguinal LN’s involved if spread to epididymis or scrotum
Lymphatic (initially) and then haematogenous spread
Haematogenous spread is most commonly to lungs; then liver, bone and brain

Question 15

Epidemiology, imaging, biochemical markers of testicular cancer

Answer 15

1% of male cancers, commonest malignancy in 15-30 y/o males; can be painful if infarction / haemorrhage
AFP elevated in 60%, beta-hCG in 50%
US - hypoechoic, with small hydrocoele in 10%

Question 16

Staging of testicular cancer

Answer 16

Low: confined to testis / epididymis / spermatic cord (T1-3), mild / moderate LNs (N1-2)
Advanced: invades scrotal wall (T4), RP LNs (N3), visceral metastases (M1)

Question 17

Testicular Microlithiasis - prevalence and associations

Answer 17

0.6% males, in 50% with germ cell tumours; 1-2 mm calcifications in seminiferous tubules; Associations with cryptorchidism, Kleinfelter’s, Down Syndrome

Question 18

Large Testicular calcifications - types and associations

Answer 18

Tumours - teratocarcinoma, seminoma, embryonal cell, Serrtoli and Leydig cell
Teratoma - large, irregular calcifications
Miscellaneous - treated cancers, old infections, haematomas, infarcts

Question 19

Testicular cysts - benign and malignant types, CFs

Answer 19

Simple cysts - 2 mm to 2 cm, >40 y/o, usually near mediastinum testis, single and non-palpable
Epidermoid cysts (keratocysts) - germ cell origin, usually palpable and non-tender, 1-3 cm, 20-40 y/o
Tunica albuginea cyst - 2-5 mm, 40 y/o, upper anterolateral testis, firm if palpable
Tubular ectasia, intratesticular varicocoele, abscess, haemorrhage
Malignant: Teratoma

Question 20

Locations of undescended testis

Answer 20

Occurs in 0.3% adult males; higher risk of torsion and malignancy (x30 risk)
Root of scrotum (50%)
Inguinal canal (20%)
Abdominal (10%) - anywhere between lower pole of kidney and internal ring
10% bilateral

Question 21

Management of testicular trauma

Answer 21

Intratesticular - surgical

Extratesticular - conservative

Question 22

Torsion - definition, bilaterality, imaging

Answer 22

Extravaginal (fetus / neonatal): twisting of testis, epididymis and tunica vaginalis in spermatic cord
Intravaginal (usually peripubertal): associated with bell clapper deformity (tunica surrounds testis - 12% males)
10% bilateral, difficult to palpate testis; Doppler approaches 100% Sn; at > 4 hours enlarged and heterogenous on greyscale, usually nonsalvagable at > 24 hours.

Question 23

Seminal vesicle cysts - size, association

Answer 23

10-20 y/o, Usually less than 3cm

Associated with ipsilateral renal agenesis; bilateral in 40-60% ADPKD

Question 24

Seminal vesicle agenesis - cause, association

Answer 24

Unilateral SV agenesis: usually due to insult before 7th week in utero, thus associated renal abnormalities: Ipsilateral renal agenesis (80%), Other renal abnormality (10%), Normal kidney (10%)
Bilateral SV agenesis: CFTR mutation in 60%, associated with bilateral vas agenesis, usually normal kidneys

Question 25

Causes of haematospermia

Answer 25

Usually cysts / calculi in any location, or local inflammation
Seminal vesicle: Amyloidosis, SV tumours
Prostate: Amyloidosis, BPH, Biopsy / TURP, Irradiation
Urethra: Stricture, Polyp

Question 26

Scrotal pearl

Answer 26

Calcified loose body between layers of tunica vaginalis

Question 27

Peyronie’s Disease - location

Answer 27

Calcified plaques in corpora cavernosa, usually peripheral

Question 28

Penile fracture - definition, imaging

Answer 28

Fracture of corpus cavernosa with tear in tunica albuginea
US: hypoechoic defect of echogenic envelope around corpora
MR: high signal defect in T1 and T2 hypointense tunica ± haemorrhage

Question 29

Penile cancer - association, histology

Answer 29

Higher risk if uncircumcised (3/1), phimosis (25%), chronic balanitis, UVA treatment, HPV
Usually SCC (95%), sarcoma (including Kaposi), melanoma, BCC, lymphoma
Rarely metastatic, usually from a urogenital source
MR Gd+ for local staging