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Testicular Microlithiasis

Definition and Etiology

Testicular microlithiasis is a common condition in patients undergoing testicular ultrasound imaging. The calcifications are caused by dead cellular material, forming calcified nuclei with concentric organic matrix layers. The microliths are 1–3 mm in size and are located in the lumen of seminiferous tubules. When more than five calcifications are visible in a sectional image, it is called classic testicular microlithiasis [fig. testicular microlithiasis]. Only single microliths are the criteria for limited testicular microlithiasis.

Epidemiology of Testicular Microlithiasis

The prevalence of classic testicular microlithiasis in patients with an indication for testicular ultrasound (e.g., pain, male infertility, or testicular tumor) is 2–4%, and limited testicular microlithiasis is detectable in 14%. Testicular microlithiasis is also associated with benign conditions: infertility, orchitis, trauma, or testicular torsion. Classic testicular microlithiasis is also a risk factor for germ cell neoplasia in situ (GCNIS) or germ cell tumors; the extent of the risk is controversial. In patients with testicular microlithiasisi and additional infertility, the risk of testicular tumor is 10–40-fold (Barbonetti et al., 2019). Other tumor risk factors in patients with microlithiasis include bilateral manifestation, atrophic testis, cryptorchidism, or germ cell tumors of the opposite side.

Diagnosis of Testicular Microlithiasis

High-resolution sonography of the testicular parenchyma shows 1–3 mm large, strongly echogenic, non-shadowing lesions.

Ultrasound imaging of classic testicular microlithiasis. With kind permission, J. Menzinger, München.

Treatment of Testicular Microlithiasis

Patients should be instructed for self-examination of the testes to enable an early detection of testicular tumors. Additional serial ultrasound examinations every 1–2 years should be offered to patients with additional risk factors (see above). Testicular biopsy is an option in patients with significantly increased risk (EAU Guideline).

References

A. Barbonetti et al., “Testicular Cancer in Infertile Men With and Without Testicular Microlithiasis: A Systematic Review and Meta-Analysis of Case-Control Studies.,” Front Endocrinol, vol. 10, p. 164, 2019, doi: 10.3389/fendo.2019.00164.

Middleton, W. D.; Teefey, S. A. & Santillan, C. S. Testicular microlithiasis: prospective analysis of prevalence and associated tumor.
Radiology 2002, 224, 425-428.

Otite, U.; Webb, J. A.; Oliver, R. T.; Badenoch, D. F. & Nargund, V. H. Testicular microlithiasis: is it a benign condition with malignant potential?
Eur Urol 2001, 40, 538-542.

A. Salonia, S. Minhas, and C. Bettocchi, “EAU Guidelines: Sexual and Reproductive Health,” 2022. [Online]. Available: https://uroweb.org/guidelines/sexual-and-reproductive-health/.

  Deutsche Version: Testikuläre Mikrolithiasis oder Sternenhimmel-Phänomen des Hodens