Diagnostic Ultrasound - Abdomen and Pelvis

Testicular Microlithiasis
TERMINOLOGY
Definitions
• Testicular microlithiasis (TML): Presence of 5 or more
microliths or microcalcifications in whole testis or 5 or more
microliths per FOV
IMAGING
General Features
• Best diagnostic clue
○ Discrete, punctate, nonshadowing echogenic foci
scattered within testicular parenchyma
• Location
○ Either unilateral or bilateral
• Size
○ 1-3 mm
• Morphology
○ Asymmetrically distributed, peripheral predominance,
impalpable
○ Microcalcifications, composed of hydroxyapatite, formed
within spermatic tubule lumina
○ Multilayered envelope, composed of stratified collagen
fibers, is considered to be responsible for absence of
acoustic shadowing
○ Majority are idiopathic; previous infection or trauma may
also be responsible
Ultrasonographic Findings
• Grayscale ultrasound
○ Small hyperechoic foci diffusely scattered throughout
testicular parenchyma
– 1-3 mm echogenic foci, no shadowing
– May occasionally see "comet-tail" artifact
– May be peripheral or segmental in distribution
– Clusters of microliths may represent testicular tumor
(carcinoma in situ) without soft tissue mass
□ Clusters of microliths adjacent to solid mass
suggests germ cell tumor (GCT)
Imaging Recommendations
• Best imaging tool
○ High resolution US (≥ 7.5 MHz) is modality of choice
○ Microliths are not visible on MR
DIFFERENTIAL DIAGNOSIS
Scrotal Pearls (Scrotoliths)
• Extratesticular calcified bodies within scrotum with no
clinical significance; result from inflammation of tunica
vaginalis or torsion of appendix testis
Large Cell Calcifying Sertoli Cell Tumor
• Gonadal stromal tumor, often bilateral and multifocal
• Most commoncause of intratesticular macrolithiasis, mass
may be almost completely calcified
Testicular Granuloma
• TB epididymoorchitis may produce intrascrotal
calcifications and scrotal sinus tract
PATHOLOGY
General Features
• Etiology
○ Exact cause is unknown
– Defect in phagocytic activity of Sertoli cells leads to
degenerated intratubular debris, genetic mutation, or
sequela of testicular tubular degeneration
○ Debris accumulates as glycoprotein and calcium layers
• Genetics
○ Associated with Klinefelter syndrome, Down syndrome,
male pseudohermaphroditism, cryptorchidism, McCune-
Albright syndrome, Peutz Jeghers syndrome
• Associated abnormalities
○ Testicular neoplasia in 18-75%, intratubular germ cell
neoplasia (IGCN)
○ Testicular microlithiasis rarely associated with
extratesticular tumors, such as epididymal or abdominal
neoplasms in absence of testicular tumor
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Asymptomatic, incidentally seen on US for other scrotal
abnormalities
Demographics
• Age
○ Usually seen in older boys and adolescents
○ Rare in boys younger than 2 years
• Epidemiology
○ 0.6%, increased detection due to frequent use of highfrequency
ultrasonography
Natural History & Prognosis
• Concurrent germ cell tumor in up to 40%
• Follow-up US recommended in patients with risk factors
○ Personal/ family history of GCT, maldescent or
undescended testes, orchidopexy, testicular atrophy
Treatment
• No treatment or follow-up or biopsy in absence of risk
factors of testicular malignancy
• If associated with hypoechoic mass, surgical biopsy, or
orchiectomy
SELECTED REFERENCES
1. Richenberg J et al: Testicular microlithiasis imaging and follow-up: guidelines
of the ESUR scrotal imaging subcommittee. Eur Radiol. 25(2):323-30, 2015
2. Cooper ML et al: Testicular microlithiasis in children and associated testicular
cancer. Radiology. 270(3):857-63, 2014
3. Chiang LW et al: Implications of incidental finding of testicular microlithiasis
in paediatric patients. J Pediatr Urol. 8(2):162-5, 2012
4. Richenberg J et al: Testicular microlithiasis: is there a need for surveillance in
the absence of other risk factors? Eur Radiol. 22(11):2540-6, 2012
5. Silveri M et al: Management and follow-up of pediatric asymptomatic
testicular microlithiasis: are we doing it well? Urol J. 8(4):287-90, 2011
6. Tan IB 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. Cancer. 116(19):4520-32, 2010
7. Dagash H et al: Testicular microlithiasis: what does it mean clinically? BJU Int.
99(1):157-60, 2007
Diagnoses: Scrotum
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