Diagnostic Ultrasound - Abdomen and Pelvis

Adenomatoid Tumor
TERMINOLOGY
Definitions
• Benign solid paratesticular tumor of mesenchymal origin
IMAGING
General Features
• Best diagnostic clue
○ Solid intrascrotal mass, usually extratesticular
• Location
○ Epididymis: Most common location overall
– Most commonly in tail
○ Tunica albuginea
○ Rarely intratesticular or other locations such as spermatic
cord and prostate
• Size
○ 5 mm to 5 cm
• Morphology
○ Rounded or ovoid
○ Well circumscribed
Imaging Recommendations
• Best imaging tool
○ US
• Protocol advice
○ Grayscale US with color Doppler imaging
Ultrasonographic Findings
• Solid mass within epididymis or tunica, varying echogenicity
○ Gentle transducer pressure may show mass can move
independently of testis
• Hypovascular or avascular on color Doppler US
• Refractive edge shadows on grayscale US
DIFFERENTIAL DIAGNOSIS
Leiomyoma
• Solid or cystic, may contain calcifications
• Most often located in epididymal head
Lipoma
• 45% of all paratesticular masses
• Composed of mature fat cells
○ Homogeneous and hyperechoic on US
○ High signal on T1-weighted MR
Cystadenoma
• Reported in 60% of men with von Hippel-Lindau disease
• May occur sporadically, typically in middle age
• May be primarily cystic, or mixed solid and cystic on US
PATHOLOGY
General Features
• Etiology
○ Unknown
○ Believed to be mesothelial in origin
Gross Pathologic & Surgical Features
• Solid, homogeneous, yellowish nodule with smooth surface
○ Most common location is tail of epididymis
• Rarely may occur in tunica, testis, or spermatic cord
• Generally not encapsulated
Microscopic Features
• Lesion composed of irregular tubules lined with flattened
and cuboid epithelial or endothelial cells
• Keratin positive on immunoperoxidase stains
• Cells are positive for mesothelial related markers (calretinin,
HMBE1)
• Increasing recognition that FNA can provide accurate
diagnosis
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Many patients are asymptomatic
○ Slowly growing palpable mass
• Other signs/symptoms
○ 5% of patients present with pain
Demographics
• Age
○ 20 years and older: Mean age 36
○ Rarely seen in boys
• Gender
○ Masses of similar histology may arise in female genital
tract as well
• Epidemiology
○ Most common solid mass in epididymis
○ 36% of all paratesticular tumors
Natural History & Prognosis
• Slowly enlarges over years
Treatment
• Most are surgically excised to confirm diagnosis, usually
testis-sparing
• Some urologists and patients elect surveillance
• Emerging role for FNA
DIAGNOSTIC CHECKLIST
Consider
• Leiomyoma
Image Interpretation Pearls
• Solid paratesticular mass
• Hypovascular or avascular on color Doppler US
SELECTED REFERENCES
1. Makkar M et al: Adenomatoid tumor of testis: A rare cytological diagnosis. J
Cytol. 30(1):65-7, 2013
2. Gupta S et al: Aspiration cytology of adenomatoid tumor of epididymis: An
important diagnostic tool. J Surg Case Rep. 2012(4):11, 2012
3. Wasnik AP et al: Scrotal pearls and pitfalls: ultrasound findings of benign
scrotal lesions. Ultrasound Q. 28(4):281-91, 2012
4. Park SB et al: Imaging features of benign solid testicular and paratesticular
lesions. Eur Radiol. 21(10):2226-34, 2011
5. Evans K: Rapidly growing adenomatoid tumor extending into testicular
parenchyma mimics testicular carcinoma. Urology. 64(3):589, 2004
6. Williams SB et al: Adenomatoid tumor of the testes. Urology. 63(4):779-81,
2004
Diagnoses: Scrotum
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