Clinical importance and prevalence of testicular microlithiasis in pediatric patients 1 Importância clínica e prevalência de microlititíase testicular em pacientes pediátricos

PuRPOsE: To evaluate the prevalence of testicular microlithiasis among pediatric patients with inguinoscrotal affections. METHOds: Between January 2005 and January 2010, we evaluated, prospectively 1504 children ranging from 1 to 15 years with inguinoscrotal affections with a high-frequency ultrasound system, which employs a 10-MHz transducer. REsuLTs: Testicular microlithiasis was identified in 20 testes of eleven children (0.71% of 1504 patients evaluated), through an ultrasound scan. Testicular microlithiasis was found in 5 children with cryptorchidism (3.93% of 127 patients), 4 children with retractile testes (14.8% of 27 patients), 1 child with a hypotrophic testis (100% of 1 patient), and 1 child with inguinal hernia (0.07% of 1349 patients). The children with testicular microlithiasis were submitted to annual physical examinations and ultrasound evaluations. CONCLusIONs: Testicular microlithiasis was a rare condition and occurred in 0.7% of the subjects studied. The association with cryptorchidism, retractile and hypotrophic testis was significant.


Introduction
Testicular microlithiasis (TM) is rare.However, it has come to be encountered more frequently due to the increased number of situations in which high-resolution ultrasound is used in the inguinoscrotal region to investigate testicular size in cryptorchidism or patency of the peritoneal-vaginal duct.The typical presentation of TM is diffuse calcification (consisting of hydroxyapatite crystals surrounded by layers of collagen fibers) in the seminiferous tubules.There is evidence that TM is a precursor of testicular germ cell tumors 1,2 and that it is associated with infertility 3 .However, it remains unknown whether these are true cause-and-effect relationships or just incidental findings.The incidence of TM is from 0.6 to 5.6% in the general population, from 0.6 to 9% in the population reporting to experts, and from 0.8 to 20% among individuals with fertility problems 4 .The incidence of TM concomitant with testicular germ cell tumors ranges from 8 to 46% 4 .The aim of the study was to evaluate the prevalence of TM among pediatric patients with inguinoscrotal affections.

Methods
Between January 2005 and January 2010, we evaluated, prospectively 1504 children ranging from 1 to 15 years (mean age: 7, 5).The children with cryptorchidism, retractile testis, hypotrophy of the testis, and inguinal hernia were submitted to ultrasound scans of the testis.The follow-up period ranged from 6 months to 5 years.

Research Ethics Committee of Triangulo Mineiro Federal
University approval was obtained.An experienced specialist operated the high-frequency ultrasound system (Power Vision 6000, Toshiba), which employs a 10-MHz transducer.TM was characterized as distributed hyperechogenic microliths measuring less than 3 mm in diameter and seen in a single ultrasound scan.
The distribution of the calcifications was diffuse or focal, uni or bilateral (Figure 1).The co-occurrence of TM with testicular tumors was not found in this study of pediatric patients.(Table 1) that cast an acoustic shadow are therefore not considered characteristic of TM 5,6 , which is defined as five or more randomly distributed hyperechogenic microliths measuring less than 3 mm in diameter and seen in a single ultrasound scan.The distribution of the calcifications can be diffuse or focal, and the TM can be unilateral or bilateral.The most common form of presentation is tiny specks of echogenic foci distributed diffusely, bilaterally, and symmetrically within the testicular parenchyma 1,7 .This pattern of presentation was found in our study.The disease was diffusely distributed and bilateral in 9 of 11 children.
Although there is no known cause of TM, it is thought to result from a degenerative process in the seminiferous tubule epithelium.This process produces cellular debris that migrates to the lumen of the seminiferous tubules and seeds the calcification 8 .
A review of the literature showed that the true incidence of TM ranges from 00.4% in autopsies to 18.1% in ultrasound examinations 9 .In our study, we found the prevalence of TM among pediatric patients with inguinoscrotal affections to be 0.71%.
There is no consensus regarding the predictive value of TM for the appearance of testicular germ cell tumors.It has been reported that 45% of patients diagnosed with TM also have testicular germ cell tumors 10 .In addition, one group of authors identified TM in 15% of patients who underwent orchiectomy for testicular cancer 11 .
TM has been shown to be correlated with conditions such as atrophic testis; varicocele; testicular torsion; sympathetic nervous system calcifications; cerebral calcifications; pseudohermaphroditism; Down's syndrome; Klinefelter's syndrome; cystic fibrosis; germ cell tumors; and carcinoma in situ 9 .
Höbarth et al. 1 found testicular tumors in 5 (44%) of 11 cases of TM.Otite et al. 12 conducted a retrospective evaluation of 3,026 patients who underwent inguinoscrotal ultrasound investigation of pain, edema, or infertility.The authors found that 54 (1.77%) presented TM, and that 16 (30%) of those were diagnosed with testicular tumors.
Up to 10% of children with cryptorchidism also present TM, which is double the TM incidence reported in children with descended testes 13 .Cryptorchidism is also a risk factor for testicular cancer, as perhaps evidenced by variations in the incidence of TM: 1% in inguinal testes; 5% in abdominal testes; and up to 25% in bilateral cryptorchid testis.Long-term follow-up evaluation of such children is therefore a priority 14 .
In the present study with pediatric patients, the undescended testes were all located at the inguinal region.
We found that 3.93% of these undescended testes had TM.We observed a significant association between retractile testes and TM

FIGuRE 1 -
FIGuRE 1 -Testicular ultrasound scan: microlithis (arrows) without acoustic shadows observed in the left testis of a 10 years old boy.
testicular microlithiasis in 1504 children with inguinoescrotal affections.discussion High-resolution inguinoscrotal ultrasound is a sensitive diagnostic tool, especially when high-frequency linear transducers are used.It has come to be more widely used in recent years due to improvements in the quality of ultrasound equipment.Inguinoscrotal ultrasound can identify scrotal calcifications, which can be either intratesticular or extratesticular.Extratesticular scrotal calcifications are more common and are associated with inflammation of the epididymis and tunica albuginea.Smaller intratesticular scrotal calcifications can be characterized as TM, whereas larger ones are typically to phlebolith, spermatic granulomas, vascular calcification, or tumors.Those