A 25-Year-Old Male with Intermittent Right Inguinal Pain, Testicular Microlithiasis

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 Testicular Microlithiasis (TM)

1. Cause and Etiology

Testicular microlithiasis (TM) is a benign condition characterized by the presence of multiple tiny calcifications within the seminiferous tubules of the testis. The exact cause is unknown, but several theories have been proposed:

  • Degeneration of the seminiferous epithelium: Intratubular debris may calcify over time.
  • Abnormal phagocytosis by Sertoli cells leads to the accumulation of laminated calcifications.
  • Involution or scarring of testicular tissue due to trauma, infection, cryptorchidism, or other insults.

Associated conditions include:

  • Testicular germ cell tumors (e.g., seminoma, embryonal carcinoma)
  • Infertility
  • Cryptorchidism
  • Klinefelter syndrome
  • Testicular atrophy

2. Pathophysiology

Microliths are composed of concentric layers of calcium phosphate that form within the lumina of seminiferous tubules. These structures are typically non-mobile and non-shadowing on imaging due to their microscopic size.

  • The process begins with degeneration or sloughing of germ cells or other intratubular material.
  • These remnants become calcified, often forming multiple deposits in each testis.
  • The presence of microliths itself does not lead to symptoms but may reflect underlying testicular pathology or altered testicular function.

3. Epidemiology

  • Prevalence: Varies widely based on population and diagnostic criteria; reported in 0.6% to 9% of asymptomatic men undergoing scrotal ultrasound.
  • Age: Most commonly detected in young adult men (20–40 years).
  • Bilateral in ~80% of cases.
  • TM is found more frequently in:
    • Infertile men
    • Men with testicular cancer (up to 40% in some series)
    • Those with a history of cryptorchidism or testicular atrophy

4. Clinical Presentation

  • Asymptomatic in most cases.
  • Usually discovered incidentally during scrotal ultrasound performed for other reasons (e.g., pain, swelling, infertility).
  • No physical signs or palpable abnormalities are typically associated with TM.
  • When associated with germ cell tumors, patients may present with:
    • Painless testicular mass
    • Scrotal heaviness or swelling
    • Gynecomastia (in hormonally active tumors)
    • Metastatic symptoms (rare in early disease)

5. Imaging Features

Ultrasound is the modality of choice.

Ultrasound Characteristics:

  • Numerous tiny hyperechoic foci (<3 mm in size) are scattered throughout the testicular parenchyma.
  • No acoustic shadowing due to their microscopic size.
  • Typically bilateral.
  • May coexist with other abnormalities such as:
    • Testicular masses
    • Atrophy
    • Heterogeneous echotexture

Grading (Non-standardized but often used):

  • Classic TM: ≥5 microliths per transducer field
  • Limited TM: <5 microliths per field
  • Diffuse TM: Widespread involvement of the entire testis

6. Treatment

No treatment is required for isolated, asymptomatic testicular microlithiasis.

Management depends on associated risk factors:

  • No risk factors (e.g., no history of cancer, normal testes):
    • Reassurance
    • Annual self-examination
    • No routine follow-up imaging is recommended by most guidelines
  • With risk factors (e.g., personal or family history of testicular cancer, infertility, undescended testis):
    • Annual or biannual scrotal ultrasound
    • Clinical testicular exams
    • Serum tumor markers (AFP, β-hCG, LDH) only if suspicion of malignancy
  • Presence of testicular mass or suspicious features:
    • Further diagnostic work-up (MRI, tumor markers, surgical exploration if indicated)

7. Prognosis

  • Excellent for isolated TM without other risk factors.
  • TM itself does not increase mortality or cause symptoms.
  • However, increased vigilance is warranted in patients with associated conditions (e.g., cryptorchidism, infertility, testicular atrophy), as they may have an elevated risk of developing germ cell tumors.

Testicular Cancer Risk:

  • Absolute risk remains low (~1–2% in asymptomatic patients without risk factors).
  • Risk is significantly higher in patients with:
    • Personal history of testicular cancer
    • Cryptorchidism
    • Testicular atrophy

Key Points Summary

Aspect

Description

Cause

Unknown; associated with degeneration of seminiferous tubules and testicular pathologies

Etiology

Idiopathic or secondary to underlying testicular conditions (e.g., cancer, trauma, cryptorchidism)

Pathophysiology

Intratubular calcification due to sloughed cellular debris or defective phagocytosis

Epidemiology

0.6–9% prevalence; common in young men; more common in infertility and testicular cancer

Clinical Presentation

Asymptomatic; incidentally found; no palpable mass unless associated with tumor

Imaging

Hyperechoic, non-shadowing foci on scrotal ultrasound; typically bilateral

Treatment

None required for isolated TM; surveillance for high-risk patients

Prognosis

Benign; good prognosis if unassociated with malignancy; monitor if risk factors present

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Case Study: A 25-Year-Old Male with Intermittent Right Inguinal Pain
Testicular Microlithiasis

History and Images

  1. A 25-year-old male presented with intermittent right inguinal pain.

  2. A scrotal ultrasound examination with color Doppler was performed.

Quiz

1. What does the hyperechoic focus seen on the ultrasound represent?

(1) Microcalcifications
(2) Fatty deposits
(3) Primary malignancy
(4) Metastatic disease

Explanation: Hyperechoic foci without posterior acoustic shadowing are characteristic of microcalcifications.

2. In which anatomical structure are these abnormalities confined?

(1) Seminiferous tubules
(2) Tunica albuginea
(3) Testicular vein

Explanation: Testicular microlithiasis is located within the testicular parenchyma, particularly in the seminiferous tubules, not in the tunica albuginea or vascular structures.

3. What is the most likely diagnosis?

(1) Testicular microlithiasis
(2) Scrotoliths
(3) Sperm granuloma
(4) Testicular vascular calcifications

Explanation: The ultrasound findings are consistent with testicular microlithiasis. Scrotoliths are benign extratesticular calcifications, usually larger. Sperm granulomas generally occur in the epididymis, and vascular calcifications typically present as linear echoes along vascular courses.

4. How many echogenic foci per ultrasound field are required to establish the diagnosis?

(1) 5
(2) 2
(3) 10
(4) 15

Explanation: The diagnostic criterion for testicular microlithiasis is the presence of at least five microcalcifications per ultrasound image.

5. What conditions are associated with this diagnosis?

(1) Cryptorchidism
(2) Male infertility
(3) Testicular cancer
(4) All of the above

Explanation: Testicular microlithiasis is associated with an increased risk of cryptorchidism, male infertility, and testicular cancer.

Findings and Diagnosis

Ultrasound Findings:

Scrotal ultrasound revealed numerous hyperechoic foci less than 3 mm in diameter in the bilateral testicular parenchyma. Color Doppler imaging showed normal vascular flow.

Differential Diagnosis:

  • Testicular microlithiasis

  • Scrotoliths

  • Sperm granuloma

  • Testicular vascular calcifications

Final Diagnosis:

Testicular microlithiasis

Discussion

Pathophysiology:

Testicular microlithiasis results from calcifications within the seminiferous tubules. The exact cause remains unclear. Genetic associations have been suggested, particularly in connection with pulmonary and central nervous system microlithiasis. Notably, patients with alveolar microlithiasis caused by mutations in the SLC34A2 gene have demonstrated concurrent testicular microlithiasis.

Epidemiology:

Testicular microlithiasis is observed in 0.6% to 9% of symptomatic adult men and 2.4% to 5.6% of asymptomatic men. Among asymptomatic males aged 0 to 19 years, it occurs in approximately 2.4%. It has been linked to male infertility, cryptorchidism, and testicular malignancy.

Clinical Features:

Most cases are asymptomatic and discovered incidentally on scrotal ultrasound. However, pain may occur in some cases due to distension of the seminiferous tubules.

Imaging Features:

The diagnosis is based on ultrasonographic identification of at least five echogenic foci, each measuring less than 3 mm in diameter, within the testicular parenchyma.

Management:

Testicular microlithiasis itself does not require treatment. However, because it may be associated with intratubular germ cell neoplasia—a precursor to testicular cancer—further evaluation may be necessary.

High-risk individuals, including those with a history of cryptorchidism, infertility, or a personal/family history of testicular cancer, should undergo annual scrotal ultrasound and regular follow-up.

Low-risk individuals are typically advised to perform monthly testicular self-examinations, with no need for routine imaging.

References

  1. Peterson AC, Bauman JM, Light DE, McMann LP, Costabile RA. Testicular microlithiasis: association with testicular pathology. J Urol. 2001;166(6):2064–2067. doi:10.1016/S0022-5347(05)65519-6

  2. DeCastro BJ, Peterson AC, Costabile RA. A diagnostic algorithm for the evaluation of testicular microlithiasis. J Urol. 2008;179(5):1424–1427. doi:10.1016/j.juro.2007.11.101

  3. Tanrikut C, McKinlay JB, Feldman HA, et al. The prevalence and predictors of testicular microlithiasis in a population-based sample of men. J Clin Ultrasound. 2010;38(5):232–237. doi:10.1002/jcu.20662

  4. Goede J, Hack WW, van der Voort-Doedens LM, Sijstermans K. Testicular microlithiasis and its association with testicular cancer: a meta-analysis. BJU Int. 2009;103(4):510–514. doi:10.1111/j.1464-410X.2008.08052.x

  5. Sharmeen S, Katz DS, Lalani T. Testicular microlithiasis: what radiologists need to know. Clin Imaging. 2015;39(3):475–480. doi:10.1016/j.clinimag.2014.11.017


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