Testicular microlithiasis (TM) is a relatively common condition that represents the deposition of multiple tiny calcifications throughout both testes.
The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In the majority of cases testicular microlithiasis is bilateral.
Testicular microlithiasis is seen in up to 0.6% of patients undergoing scrotal ultrasound. Some reports suggest that it may present in up to 5.6% of the general population between 17 and 35 years of age 3. Although testicular microlithiasis is present in ~50% of men with a germ cell tumour, it is very common in patients without cancer, and a direct relationship between the two has been debated.
The microcalcifications are likely a marker of tubular degeneration, but not a risk factor for tubular degeneration 10.
Testicular microlithiasis per se is asymptomatic and is usually found incidentally when the scrotal content is examined with ultrasound, or found in association with symptomatic conditions.
Known associations include:
- testicular germ cell tumour
- Klinefelter syndrome
- testicular infarct
- Down syndrome
- alveolar microlithiasis
Ultrasound is the modality of choice for examining the testes. Microlithiasis appears as small non-shadowing hyperechoic foci ranging in diameter from 1-3 mm. These foci occur within the testicular parenchyma and although usually distributed uniformly, may be distributed peripherally or segmentally 2.
One grading system used on ultrasound is 13:
- grade I: 5-10 microcalcifications
- grade II: 11 to 20 microcalcifications
- grade III: 21 to 30 microcalcifications
- grade IV: >30 microcalcifications
It is unclear if a grading system adds prognostic value.
Treatment and prognosis
Testicular microlithiasis is in itself asymptomatic and benign. A relationship with testicular tumours, in particular germ cell tumours (GCT) is controversial. An ~8 fold increased risk of GCT in symptomatic testicles with microlithiasis has been reported (with microlithiasis found in approximately 50% of GCT cases), however, no increased risk has been found in asymptomatic testicles. It is also unclear whether early detection confers any benefit over self-exam. As such, screening is unlikely to be beneficial 1.
Some publications advise routine self-examination rather than sonographic surveillance 5 while others recommend annual ultrasound follow up when it is accompanied by other premalignant factors 6.
The European Society of Urogenital Radiology (ESUR) advises annual ultrasound follow-up until age 55, only if a risk factor is present 12 which include:
- personal or family history of germ cell tumour
- testicular atrophy
- 1. Tan IB, Ang KK, Ching BC et-al. Testicular microlithiasis predicts concurrent testicular germ cell tumors and intratubular germ cell neoplasia of unclassified type in adults: a meta-analysis and systematic review. 2010;doi:10.1002/cncr.25231 - Pubmed citation
- 2. Cast JE, Nelson WM, Early AS et-al. Testicular microlithiasis: prevalence and tumor risk in a population referred for scrotal sonography. AJR Am J Roentgenol. 2000;175 (6): 1703-6. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Costabile RA. How worrisome is testicular microlithiasis?. Curr Opin Urol. 2007;17 (6): 419-23. doi:10.1097/MOU.0b013e3282f0ffea - Pubmed citation
- 4. Shanmugasundaram R, Singh JC, Kekre NS. Testicular microlithiasis: Is there an agreed protocol?. Indian J Urol. 2007;23 (3): 234-9. doi:10.4103/0970-1591.33442 - Free text at pubmed - Pubmed citation
- 5. DeCastro BJ, Peterson AC, Costabile RA. A 5-year followup study of asymptomatic men with testicular microlithiasis. J. Urol. 2008;179 (4): 1420-3. doi:10.1016/j.juro.2007.11.080 - Pubmed citation
- 6. Dagash H, Mackinnon EA. Testicular microlithiasis: what does it mean clinically?. BJU Int. 2007;99 (1): 157-60. doi:10.1111/j.1464-410X.2006.06546.x - Pubmed citation
- 7. Otite U, Webb JA, Oliver RT et-al. Testicular microlithiasis: is it a benign condition with malignant potential?. Eur. Urol. 2002;40 (5): 538-42. Pubmed citation
- 8. Dell'Acqua A, Tomà P, Oddone M et-al. Testicular microlithiasis: US findings in six pediatric cases and literature review. Eur Radiol. 1999;9 (5): 940-4. Pubmed citation
- 9. Miller FN, Sidhu PS. Does testicular microlithiasis matter? A review. Clin Radiol. 2002;57 (10): 883-90. Pubmed citation
- 10. Winter TC, Kim B, Lowrance WT, Middleton WD. Testicular Microlithiasis: What Should You Recommend?. AJR. American journal of roentgenology. 206 (6): 1164-9. doi:10.2214/AJR.15.15226 - Pubmed
- 11. de Gouveia Brazao CA, Pierik FH, Oosterhuis JW et-al. Bilateral testicular microlithiasis predicts the presence of the precursor of testicular germ cell tumors in subfertile men. J. Urol. 2004;171 (1): 158-60. doi:10.1097/01.ju.0000093440.47816.88 - Pubmed citation
- 12. Richenberg J, Belfield J, Ramchandani P et-al. Testicular microlithiasis imaging and follow-up: guidelines of the ESUR scrotal imaging subcommittee. Eur Radiol. 2015;25 (2): 323-30. doi:10.1007/s00330-014-3437-x - Pubmed citation
- 13. Richenberg J, Brejt N. Testicular microlithiasis: is there a need for surveillance in the absence of other risk factors?. European radiology. 22 (11): 2540-6. doi:10.1007/s00330-012-2520-4 - Pubmed
Ultrasound - testicular and scrotal
- ultrasound (introduction)
testicular and scrotal ultrasound
unilateral testicular lesion
- testicular torsion
- testicular rupture
- germ cell tumours of the testis
- sex cord / stromal tumours of the testis
- bilateral testicular lesion
- paratesticular lesions
- tubular ectasia of the rete testis
- cystadenoma of the rete testis
- testicular sarcoidosis
- testicular tuberculosis
- spermatic cord
- fibrous pseudotumour of the scrotum
- scrotal leiomyosarcoma
- testicular adrenal rest tumours (TARTs)
- tunica vaginalis testis mesothelioma
- splenogonadal fusion
- unilateral testicular lesion