Question 1: Testicular Torsion
Stem: A 16-year-old boy presents to the emergency department with a 3-hour history of acute, severe, left-sided testicular pain and nausea. A colour Doppler ultrasound of the scrotum is performed. It shows an enlarged, oedematous left testis with a complete absence of internal arterial and venous flow. Flow is normal on the asymptomatic right side.
Question: What is the most likely diagnosis?
(A) Acute Epididymo-orchitis (B) Testicular Torsion (C) Strangulated Inguinal Hernia (D) Torsion of the Appendix Testis (E) Testicular Tumour
Correct Answer: (B) Testicular Torsion.
Explanation:
- Why (B) is correct: The combination of acute, severe pain in an adolescent and the total absence of blood flow on colour Doppler is the classic and definitive sign of testicular torsion. This is a surgical emergency requiring immediate exploration, as the testis is non-viable after 6-12 hours.
- Why (A) is wrong: Acute epididymo-orchitis is an infection and would show increased blood flow (hyperaemia) to the epididymis and testis, not absent flow.
- Why (C) is wrong: A strangulated hernia would show bowel loops in the scrotum, and the testis itself would still have blood flow (unless the strangulation was very large and compressed the cord, which is less likely).
- Why (D) is wrong: Torsion of the appendix testis (a small remnant) is also a cause of acute pain, but it presents as a small, avascular nodule, and the testis itself retains normal blood flow. This is the key differentiator.
- Why (E) is wrong: A tumour is a chronic process and would present as a palpable mass, not acute pain. It would have abnormal internal flow, not absent flow.
Key Points: Testicular Torsion
- Definition: Twisting of the spermatic cord, cutting off the testicular blood supply.
- Clinical: Acute, severe pain (often with high-riding testis). A surgical emergency.
- Ultrasound (Key Sign): Absence of arterial and venous flow on colour Doppler.
- Appearance: Testis may be enlarged and hypoechoic (oedema/infarction). The “whirlpool sign” (twisted cord) may be seen.
Question 2: Acute Epididymo-orchitis
Stem: A 30-year-old sexually active man presents with a 3-day history of gradually worsening right scrotal pain, swelling, and fever. A Doppler ultrasound shows an enlarged, hypoechoic epididymal head with markedly increased blood flow (hyperaemia). The adjacent testis also appears hyperaemic.
Question: What is the most likely diagnosis?
(A) Testicular Torsion (B) Acute Epididymo-orchitis (C) Testicular Abscess (D) Varicocele (E) Testicular Tumour
Correct Answer: (B) Acute Epididymo-orchitis.
Explanation:
- Why (B) is correct: This is the classic ultrasound appearance of an infection. The key finding is increased blood flow (hyperaemia), which is the opposite of torsion. The inflammation typically starts in the epididymis (epididymitis) and then spreads to the testis (orchitis).
- Why (A) is wrong: Torsion would show absent blood flow.
- Why (C) is wrong: An abscess is a complication of epididymo-orchitis and would appear as a focal, avascular, fluid-filled collection with a thick, enhancing rim.
- Why (D) is wrong: A varicocele is a collection of dilated veins, not an inflamed epididymis.
- Why (E) is wrong: A tumour is a solid mass with internal (often abnormal) vascularity, not diffuse hyperaemia of the entire epididymis and testis.
Key Points: Acute Epididymo-orchitis
- Definition: Inflammation/infection of the epididymis and testis.
- Causes: <35 years old (STI – Chlamydia, Gonorrhoea); >35 years old (UTI – E. coli).
- Ultrasound (Key Sign): Increased blood flow (hyperaemia) on colour Doppler.
- Appearance: Enlarged, hypoechoic epididymis (usually the head first) and/or testis. A reactive hydrocele is common.
Question 3: Testicular Tumour (Seminoma)
Stem: A 35-year-old man presents with a painless, heavy sensation in his right testis. An ultrasound reveals a 3 cm, solid, well-defined, homogeneous, hypoechoic mass within the testicular parenchyma, without calcification or cystic change.
Question: This appearance is most characteristic of which testicular tumour?
(A) Seminoma (B) Teratoma (C) Choriocarcinoma (D) Yolk Sac Tumour (E) Epidermoid Cyst
Correct Answer: (A) Seminoma.
Explanation:
- Why (A) is correct: Seminoma is the most common primary testicular tumour. It is classic for its homogeneous, hypoechoic appearance on ultrasound. It is typically well-defined and lacks the cysts and calcifications seen in non-seminomatous tumours.
- Why (B) is wrong: Teratoma (a non-seminomatous germ cell tumour, NSGCT) is classically heterogeneous, containing cystic areas and calcifications (representing cartilage, bone, etc.).
- Why (C) & (D) are wrong: Choriocarcinoma and Yolk Sac Tumour are also NSGCTs, which are typically heterogeneous and aggressive.
- Why (E) is wrong: An epidermoid cyst is a benign “tumour” that classically has a well-defined, “onion-skin” or “target” appearance, and is avascular.
Key Points: Seminoma
- Most common primary testicular germ cell tumour.
- Ultrasound (Classic): Homogeneous, hypoechoic, well-defined solid mass.
- Tumour Markers: Typically normal AFP. May have mildly elevated beta-hCG (~15%).
- Prognosis: Excellent; very radiosensitive and chemosensitive.
Question 4: Testicular Tumour (Non-Seminoma)
Stem: A 25-year-old man presents with a hard, irregular testicular mass. An ultrasound shows a large, infiltrative, heterogeneous solid mass containing multiple cystic spaces and coarse, punctate calcifications. Serum tumour markers show a markedly elevated Alpha-fetoprotein (AFP).
Question: This appearance and the elevated AFP are most characteristic of:
(A) Seminoma (B) Non-Seminomatous Germ Cell Tumour (NSGCT) (C) Lymphoma (D) Epidermoid Cyst (E) Testicular Abscess
Correct Answer: (B) Non-Seminomatous Germ Cell Tumour (NSGCT).
Explanation:
- Why (B) is correct: This is the classic picture of an NSGCT (e.g., mixed germ cell tumour, teratoma, yolk sac tumour). They are defined by their heterogeneous appearance, often containing cystic change, haemorrhage, and calcification. A markedly elevated AFP is a specific marker for non-seminomatous components (especially yolk sac tumour) and rules out a pure seminoma.
- Why (A) is wrong: A pure seminoma is homogeneous, hypoechoic, and never produces AFP.
- Why (C) is wrong: Lymphoma is the most common bilateral tumour in older men (>60) and is typically hypoechoic and homogeneous, mimicking seminoma.
- Why (D) is wrong: An epidermoid cyst has an “onion-skin” appearance and is benign.
- Why (E) is wrong: An abscess is a complex fluid collection with clinical signs of infection.
Key Points: Non-Seminomatous GCT (NSGCT)
- Includes: Teratoma, Yolk Sac Tumour, Choriocarcinoma, Embryonal Carcinoma, or mixed.
- Ultrasound (Classic): Heterogeneous, infiltrative mass with cystic areas, haemorrhage, and calcifications.
- Tumour Markers: Often elevated AFP and/or beta-hCG.
Question 5: Varicocele
Stem: A 32-year-old man is being investigated for infertility. A scrotal ultrasound demonstrates a collection of multiple, dilated, serpiginous, anechoic tubules, each measuring > 3 mm in diameter, located in the pampiniform plexus, superior and posterior to the left testis. These tubules show increased flow on colour Doppler and augment with the Valsalva manoeuvre.
Question: What is the most likely diagnosis?
(A) Hydrocele (B) Spermatocele (C) Epididymo-orchitis (D) Varicocele (E) Tubular Ectasia of the Rete Testis
Correct Answer: (D) Varicocele.
Explanation:
- Why (D) is correct: This is the classic ultrasound description of a varicocele, which is a dilatation of the pampiniform plexus veins. The key findings are dilated, serpiginous tubules > 2-3 mm, which augment with Valsalva. They are much more common on the left (due to the left testicular vein’s drainage into the left renal vein).
- Why (A) is wrong: A hydrocele is a simple, anechoic fluid collection surrounding the testis, between the layers of the tunica vaginalis.
- Why (B) is wrong: A spermatocele is a simple cyst in the epididymal head containing sperm.
- Why (C) is wrong: Epididymo-orchitis is an inflammatory process with hyperaemia of the epididymis/testis.
- Why (E) is wrong: Tubular ectasia is a benign, non-vascular dilatation of the rete testis (at the testicular hilum), usually seen in older men.
Key Points: Varicocele
- Definition: Dilatation of the pampiniform plexus veins.
- Location: ~90% are left-sided. (A new, solitary right-sided varicocele is suspicious for retroperitoneal pathology, e.g., RCC with renal vein thrombosis).
- Clinical: A “bag of worms” on palpation. Associated with infertility and testicular atrophy.
- Ultrasound: Dilated (> 2-3 mm) veins, which show reflux and augmentation with Valsalva.
Question 6: Prostate Cancer (Staging)
Stem: A 68-year-old man with a PSA of 15 ng/mL and a positive biopsy for prostate adenocarcinoma undergoes a multiparametric MRI for staging. The T2-weighted images show a large, hypointense (dark) lesion in the peripheral zone of the right prostate, which bulges the prostatic capsule and extends into the periprostatic fat.
Question: This finding of extension into the periprostatic fat classifies this tumour as at least:
(A) T1 (B) T2 (C) T3a (D) T3b (E) T4
Correct Answer: (C) T3a.
Explanation:
- Why (C) is correct: The TNM staging for prostate cancer is based on the tumour’s extent.
- T1 = Non-palpable, non-visible on imaging.
- T2 = Tumour confined within the prostate capsule.
- T3a = Tumour extends through the capsule (Extraprostatic Extension – EPE), as described in the stem.
- T3b = Tumour invades the seminal vesicles.
- T4 = Tumour invades adjacent organs (e.g., bladder, rectum).
- This patient has EPE, making the stage at least T3a.
Key Points: Prostate Cancer (MRI Staging)
- Location: ~70-80% arise in the Peripheral Zone (PZ).
- mpMRI Appearance (PIRADS):
- T2: Hypointense (dark) nodule in the bright peripheral zone.
- DWI: Restricted diffusion (bright on high b-value, dark on ADC map).
- DCE: Early, avid enhancement and washout.
- Staging: Look for:
- T3a (EPE): Bulging/irregularity of the capsule, stranding in periprostatic fat.
- T3b: Invasion of the seminal vesicles.
- T4: Invasion of the bladder neck or rectum.
Question 7: Benign Prostatic Hyperplasia (BPH)
Stem: A 75-year-old man presents with a weak urinary stream, nocturia, and incomplete emptying. A pelvic MRI is performed. It demonstrates symmetric, nodular enlargement of the transitional zone of the prostate, which is compressing the urethra. The bladder wall appears thickened and trabeculated.
Question: What is the most likely diagnosis?
(A) Benign Prostatic Hyperplasia (BPH) (B) Prostate Adenocarcinoma (Peripheral Zone) (C) Prostatic Abscess (D) Prostatitis (E) Seminal Vesicle Invasion
Correct Answer: (A) Benign Prostatic Hyperplasia (BPH).
Explanation:
- Why (A) is correct: BPH is a benign proliferation of glandular and stromal tissue, and it exclusively arises in the transitional zone (and periurethral glands). This enlargement compresses the urethra (causing the symptoms) and the peripheral zone. The secondary signs of bladder outlet obstruction (trabeculation, diverticula) are also classic.
- Why (B) is wrong: Prostate cancer typically arises in the peripheral zone and appears as a dark, infiltrative lesion.
- Why (C) is wrong: An abscess is a rim-enhancing fluid collection, associated with fever.
- Why (D) is wrong: Prostatitis is an inflammatory condition, often appearing as diffuse enhancement or a low-T2 signal in the peripheral zone, but not nodular enlargement of the transitional zone.
- Why (E) is wrong: This is a sign of advanced cancer, not BPH.
Key Points: Benign Prostatic Hyperplasia (BPH)
- Definition: Benign nodular enlargement of the prostate.
- Location: Arises from the Transitional Zone (TZ).
- Clinical: Lower urinary tract symptoms (LUTS) – weak stream, frequency, urgency, nocturia.
- Imaging:
- Nodular enlargement of the TZ (often heterogeneous “mixed” signal on T2).
- Compression of the peripheral zone into a “surgical capsule.”
- Secondary bladder changes (wall trabeculation, diverticula, post-void residual).
Question 8: Fournier’s Gangrene
Stem: A 60-year-old diabetic man presents with acute, severe pain, swelling, and crepitus of the scrotum and perineum. He is febrile and in septic shock. A CT scan of the pelvis is performed.
Question: What is the most critical and life-threatening finding to look for on the CT scan?
(A) Subcutaneous gas (emphysema) in the scrotal wall and perineum. (B) A complex hydrocele. (C) Testicular abscesses. (D) A strangulated inguinal hernia. (E) Prostatic abscess.
Correct Answer: (A) Subcutaneous gas (emphysema) in the scrotal wall and perineum.
Explanation:
- Why (A) is correct: This is the clinical and radiological presentation of Fournier’s gangrene, a life-threatening, necrotising fasciitis of the perineum/genitalia. It is caused by gas-forming organisms. The pathognomonic finding on CT is subcutaneous gas (emphysema), which tracks along the fascial planes (Colles’, Scarpa’s) of the scrotum, perineum, and anterior abdominal wall.
- Why (B) is wrong: A hydrocele is simple fluid, not a life-threatening infection.
- Why (C) is wrong: Testicular abscesses may be present, but the spreading subcutaneous gas is the defining feature of Fournier’s.
- Why (D) is wrong: A hernia is a different pathology.
- Why (E) is wrong: A prostatic abscess is a deep infection, not a superficial necrotising fasciitis.
Key Points: Fournier’s Gangrene
- Definition: A life-threatening, necrotising fasciitis of the perineum.
- Risk Factors: Diabetes, alcoholism, immunocompromise.
- Clinical: Acute pain, swelling, crepitus, systemic sepsis.
- CT Finding (Pathognomonic): Subcutaneous gas (emphysema) in the scrotum, perineum, and inguinal regions, often tracking up the anterior abdominal wall.
- Note: This is a surgical emergency requiring immediate, wide debridement.
Question 9: Penile Fracture
Stem: A 30-year-old man presents to the ED after hearing an “audible snap” with immediate pain and detumescence during sexual intercourse. He has a large, “eggplant” deformity of his penis. An ultrasound is performed.
Question: What is the specific anatomical structure that is torn in this injury?
(A) Tunica albuginea of the corpus cavernosum. (B) Tunica albuginea of the corpus spongiosum. (C) The urethra. (D) The dorsal artery of the penis. (E) The suspensory ligament.
Correct Answer: (A) Tunica albuginea of the corpus cavernosum.
Explanation:
- Why (A) is correct: A penile fracture is a traumatic rupture of the tunica albuginea (the fibrous sheath) surrounding one or both corpora cavernosa. This occurs during forced bending of the erect penis, leading to an audible “snap,” immediate detumescence, pain, and a large haematoma (the “eggplant deformity”).
- Why (B) is wrong: The corpus spongiosum (which contains the urethra) is less commonly injured.
- Why (C) is wrong: A urethral injury is an associated injury in 10-20% of cases, but the primary “fracture” is of the corpus cavernosum’s tunic.
- Why (D) & (E) are wrong: These are different structures and not involved in a “penile fracture.”
Key Points: Penile Fracture
- Definition: Traumatic rupture of the tunica albuginea of the corpora cavernosa.
- Mechanism: Blunt trauma to the erect penis (e.g., intercourse, rolling over).
- Clinical: Audible “snap,” rapid detumescence, pain, haematoma (“eggplant deformity”).
- Imaging (Ultrasound or MRI): Look for a focal defect (tear) in the echogenic/dark tunica albuginea, with an overlying haematoma.
- Associated Injury: Urethral injury (10-20%) – a retrograde urethrogram (RUG) is often performed.
Question 10: Spermatocele / Epididymal Cyst
Stem: A 50-year-old man has an incidental finding on a scrotal ultrasound. There is a 1.5 cm, simple, anechoic, thin-walled cyst with posterior acoustic enhancement, located in the head of the epididymis.
Question: What is the most likely diagnosis?
(A) Spermatocele / Epididymal Cyst (B) Hydrocele (C) Varicocele (D) Testicular Cyst (E) Cystic Teratoma
Correct Answer: (A) Spermatocele / Epididymal Cyst.
Explanation:
- Why (A) is correct: This is the classic appearance and location. Spermatoceles and epididymal cysts are both benign cysts that arise from the epididymis, most commonly in the epididymal head. They are sonographically identical (simple, anechoic cysts). (A spermatocele technically contains sperm, but this cannot be differentiated on US).
- Why (B) is wrong: A hydrocele is a fluid collection surrounding the entire testis, between the layers of the tunica vaginalis.
- Why (C) is wrong: A varicocele is a collection of dilated veins (tubular, not cystic).
- Why (D) is wrong: A testicular cyst arises from within the testicular parenchyma, not the epididymis.
- Why (E) is wrong: A cystic teratoma is a complex mass (solid and cystic), not a simple cyst.
Key Points: Epididymal Cyst / Spermatocele
- Definition: Extremely common, benign cysts.
- Location: Arise from the epididymis, most commonly the epididymal head.
- Ultrasound: Simple, thin-walled, anechoic cyst with posterior acoustic enhancement, located outside the testis.
Question 11: Undescended Testis (Cryptorchidism)
Stem: A 3-year-old boy is referred for an “empty scrotum.” An MRI of the pelvis is performed, which locates the undescended right testis as a small, ovoid soft-tissue structure within the superficial inguinal pouch.
Question: This patient is at a significantly increased risk of developing which of the following in the undescended testis?
(A) Testicular Malignancy (Seminoma) (B) Epididymo-orchitis (C) Testicular Torsion (D) Infertility (E) All of the above
Correct Answer: (E) All of the above.
Explanation:
- Why (E) is correct: An undescended testis (cryptorchidism) carries several significant long-term risks:
- Malignancy: A 4-10x increased risk of testicular cancer (most commonly seminoma) in both the undescended and the normally-descended testis.
- Infertility: The higher temperature of the abdomen/groin impairs spermatogenesis.
- Torsion: The testis is not “fixed” in the scrotum, making it more mobile and prone to torsion.
- Trauma/Hernia: The testis is in an abnormal location and often associated with an inguinal hernia.
- Since A, B, C, and D are all well-known complications, (E) is the most complete answer.
Key Points: Undescended Testis (Cryptorchidism)
- Definition: Failure of the testis to descend into the scrotum.
- Most Common Location: Inguinal canal or superficial inguinal pouch.
- Imaging: Ultrasound is the first-line investigation. MRI is used if the testis is non-palpable and not seen on US.
- Complications: Infertility and Malignancy (Seminoma) are the two major long-term risks. Also, torsion and hernia.
Question 12: Testicular Trauma (Rupture)
Stem: A 25-year-old man is struck in the scrotum by a baseball. A scrotal ultrasound reveals a large, complex haematocele (blood collection). The underlying testis is heterogeneous, and there is a focal, visible disruption of the echogenic tunica albuginea, with extrusion of testicular parenchyma.
Question: What is the diagnosis?
(A) Testicular Rupture (B) Testicular Haematoma (C) Testicular Torsion (D) Acute Epididymitis (E) Penile Fracture
Correct Answer: (A) Testicular Rupture.
Explanation:
- Why (A) is correct: This is the definition of a testicular rupture. The key finding is the disruption (tear) of the tunica albuginea (the white, echogenic capsule). This is often associated with a large haematocele and extrusion of the testicular contents. This is a surgical emergency.
- Why (B) is wrong: A testicular haematoma (or “contusion”) implies bleeding within the testis, but the tunica albuginea is intact.
- Why (C) is wrong: Torsion is a vascular event, not a traumatic one.
- Why (D) is wrong: This is an inflammatory process.
- Why (E) is wrong: This involves the penis, not the testis.
Key Points: Testicular Trauma
- Ultrasound is the imaging modality of choice.
- Haematocele: Blood collection outside the testis (between the tunica vaginalis layers).
- Haematoma: Blood collection inside the testis.
- Testicular Rupture (Surgical Emergency):
- Disruption of the tunica albuginea.
- Extrusion of testicular parenchyma.
- Large, complex haematocele is common.
Question 13: Prostatic Abscess
Stem: A 58-year-old diabetic man presents with high fever, dysuria, and pelvic pain. A transrectal ultrasound (TRUS) reveals a 3 cm, complex, thick-walled, hypoechoic collection with internal debris, located within the peripheral zone of the prostate.
Question: What is the most likely diagnosis?
(A) Prostatic Abscess (B) Benign Prostatic Hyperplasia (BPH) (C) Prostatic Adenocarcinoma (D) Haemorrhagic Prostatic Cyst (E) Seminal Vesiculitis
Correct Answer: (A) Prostatic Abscess.
Explanation:
- Why (A) is correct: The clinical context (fever, dysuria, diabetes) and the imaging findings (a complex, thick-walled fluid collection with debris) are classic for a prostatic abscess. This is a complication of acute bacterial prostatitis.
- Why (B) is wrong: BPH is a benign nodular enlargement of the transitional zone, not a cystic, inflammatory collection.
- Why (C) is wrong: Adenocarcinoma is a solid, hypoechoic tumour in the peripheral zone, not a fluid collection.
- Why (D) is wrong: A simple or haemorrhagic cyst would not have a thick, irregular wall or be associated with high fever.
- Why (E) is wrong: This is inflammation of the seminal vesicles, which would appear dilated and inflamed, separate from the prostate.
Key Points: Prostatic Abscess
- Definition: A focal, purulent collection within the prostate gland.
- Risk Factors: Diabetes, recent instrumentation, chronic catheter, acute prostatitis.
- Clinical: High fever, pelvic pain, dysuria, urinary retention.
- Imaging (TRUS/MRI/CT):
- Thick-walled, rim-enhancing, complex fluid collection within the prostate (often peripheral zone).
- May show internal debris or gas.
Question 14: Testicular Microlithiasis
Stem: A 30-year-old man has a scrotal ultrasound for infertility. The scan is otherwise normal, but both testes demonstrate multiple, tiny (1-2 mm), non-shadowing, echogenic foci scattered throughout the parenchyma, described as a “starry sky” appearance.
Question: What is this finding, and what is its main clinical significance?
(A) Testicular Microlithiasis; associated with increased risk of malignancy. (B) Healed Granulomatous Disease; no significance. (C) Punctate Calcifications (Teratoma); diagnostic of malignancy. (D) Dystrophic Calcification; associated with prior trauma. (E) Arterial Calcifications; associated with diabetes.
Correct Answer: (A) Testicular Microlithiasis; associated with increased risk of malignancy.
Explanation:
- Why (A) is correct: This is the definition of testicular microlithiasis (>5 microcalcifications per view). The “starry sky” appearance is classic. While often benign and incidental, it is associated with an increased risk of developing testicular germ cell tumours, especially seminoma. It is also linked to infertility.
- Why (B) is wrong: Healed granulomas (e.g., from TB) are typically larger, coarser, and shadowing calcifications.
- Why (C) is wrong: The calcifications in a teratoma are coarse, part of a heterogeneous mass, not diffuse, tiny, non-shadowing specks.
- Why (D) & (E) are wrong: These are different types of calcification. The non-shadowing, “starry sky” appearance is specific to microlithiasis.
Key Points: Testicular Microlithiasis
- Definition: Multiple, tiny, non-shadowing echogenic foci within the testicular parenchyma.
- Appearance: “Starry sky” on ultrasound.
- Significance: Considered a risk factor for testicular germ cell tumours (though the absolute risk is still low). Also associated with infertility.
- Management: Often leads to a recommendation for regular testicular self-examination.
Question 15: Epidermoid Cyst (Testis)
Stem: A 28-year-old man has an incidental finding of a non-tender, 1.5 cm testicular nodule. An ultrasound shows a well-defined, avascular, intratesticular mass. The mass has a distinct laminated, “onion-skin” appearance, with alternating concentric rings of hyperechogenicity and hypoechogenicity.
Question: This “onion-skin” appearance is pathognomonic for:
(A) Epidermoid Cyst (B) Seminoma (C) Teratoma (D) Testicular Abscess (E) Haematoma (Chronic)
Correct Answer: (A) Epidermoid Cyst.
Explanation:
- Why (A) is correct: The “onion-skin” (or laminated/target) appearance is pathognomonic for a testicular epidermoid cyst. This is a benign, non-neoplastic cyst containing lamellated keratin. It is avascular, which helps differentiate it from a malignant tumour.
- Why (B) is wrong: A seminoma is a solid, homogeneous, hypoechoic, vascular mass.
- Why (C) is wrong: A teratoma is a heterogeneous, vascular, solid-and-cystic mass.
- Why (D) is wrong: An abscess is a complex fluid collection with a thick, hyperaemic rim.
- Why (E) is wrong: A chronic haematoma would be a hypoechoic or anechoic collection, not a well-organised “onion-skin” mass.
Key Points: Epidermoid Cyst (Testis)
- Definition: A benign, keratin-filled cyst of the testis (not a germ cell tumour).
- Imaging (Pathognomonic):
- “Onion-Skin” Sign: Concentric, alternating hyper- and hypoechoic rings.
- “Target” Sign (whorled appearance) is also described.
- Well-defined, no internal vascularity.
- Management: It is benign; testicular-sparing surgery (enucleation) is performed rather than orchiectomy.
