Simple testicular cyst is a rare benign cystic lesion of the testis, generally detected incidentally. It is a unilocular cystic structure lined by thin, smooth epithelial wall containing serous fluid. On ultrasonography, it appears as a completely anechoic, thin-walled, well-defined cystic lesion with posterior acoustic enhancement and is completely avascular on Doppler. Tumor markers are always normal. It has no clinical significance and requires no treatment — ultrasonographic follow-up is sufficient. Distinguished from tunica albuginea cysts by intratesticular location.
Age Range
40-70
Peak Age
55
Gender
Male predominant
Prevalence
Common
Simple testicular cyst is a benign cystic lesion of rete testis or seminiferous tubule epithelial origin. The cyst wall is lined by single-layer cuboidal or flat epithelium and contains serous fluid. Although pathogenesis is not fully understood, it is thought to develop from focal dilation of seminiferous tubules, cystic expansion of rete testis, or obstruction of efferent ductules. The completely anechoic appearance on ultrasonography reflects the cyst content being homogeneous serous fluid — as no particles, cells, or debris are present in the fluid, ultrasound waves transmit unimpeded and posterior acoustic enhancement occurs. Simple cyst is not neoplastic, not associated with GCNIS, and has no malignant transformation potential. Prevalence increases with age and is more commonly detected in men over 40 years.
A completely anechoic, thin and smooth-walled intratesticular cystic lesion with posterior acoustic enhancement on ultrasonography and completely avascular structure on Doppler is pathognomonic for simple testicular cyst. When all four criteria are met together, the diagnosis is definitive and no further investigation is needed.
Simple testicular cyst appears as a completely anechoic (black), thin-walled, round-oval, well-defined intratesticular lesion on ultrasonography. Posterior (dorsal) acoustic enhancement is characteristic with signal increase behind the cyst. Cyst wall is thin (<1 mm), smooth, and sharp without mural nodule, papillary projection, or septa. No echoes within the internal structure — no debris, hemorrhage, or solid component. Size is usually small (<2 cm).
Report Sentence
A completely anechoic, thin-walled cystic lesion with posterior acoustic enhancement is seen in the testicular parenchyma, consistent with simple cyst.
Simple testicular cyst is completely avascular on color and power Doppler. No vascular flow detected in cyst wall or content. This finding is critically important in distinguishing from cystic neoplasms (cystic teratoma, cystic seminoma). Normal vascularity preserved in surrounding testicular parenchyma.
Report Sentence
The cystic lesion is completely avascular on color and power Doppler examination; neoplastic lesion is not considered.
On T2-weighted MRI, simple cyst shows homogeneous high signal — serous fluid produces bright signal with long T2 relaxation time. Cyst wall is seen as thin, hypointense linear structure. No heterogeneity, solid component, or debris in internal structure. This homogeneous T2 hyperintensity indicates the cyst content is pure fluid.
Report Sentence
A homogeneous high-signal, thin-walled cystic lesion is seen on T2-weighted sequences, consistent with simple cyst.
On T1-weighted MRI, simple cyst shows homogeneous low signal. No enhancement on contrast-enhanced series. No signal change on fat-suppressed sequences. These findings together confirm simple serous fluid content and provide distinction from complicated cyst or neoplastic lesion.
Report Sentence
The cystic lesion shows homogeneous low signal on T1-weighted sequences with no enhancement on contrast-enhanced series.
Simple cyst shows no diffusion restriction on DWI. Signal decreases at high b-values and high ADC values (>2.0 × 10⁻³ mm²/s) are seen on the ADC map. This finding reflects free water diffusion and is important in distinguishing from cellular tumors and keratinous lesions (epidermoid cyst).
Report Sentence
The cystic lesion shows no diffusion restriction on DWI with high ADC values on the ADC map, consistent with free fluid content.
On CT, simple cyst appears as a well-defined, low-density intratesticular lesion at water density (0-20 HU). No enhancement on contrast-enhanced CT. CT is not the primary modality for simple cyst diagnosis and ultrasonography is sufficient.
Report Sentence
A well-defined cystic lesion at water density is seen in the testicular parenchyma on CT.
Criteria
Single, well-defined cyst. Most common type. Usually <2 cm. Asymptomatic.
Distinct Features
Classic simple cyst criteria on US (anechoic, thin-walled, posterior enhancement, avascular). Follow-up sufficient.
Criteria
More than one simple cyst. More common in older men. May be bilateral. Each meets separate simple cyst criteria.
Distinct Features
Multiple cysts should not be confused with cystic dysplasia. Each cyst meeting simple cyst criteria separately is important.
Criteria
Cyst of tunica albuginea origin, localized on the peripheral surface of testis. Not intratesticular. Compatible with simple cyst criteria but different location.
Distinct Features
Localized peripherally on testis, associated with tunica albuginea. True intratesticular cyst is within parenchyma. Clinical significance and management same — follow-up sufficient.
Distinguishing Feature
Epidermoid cyst is not anechoic — shows concentric ring ('onion ring') pattern. Simple cyst is completely anechoic. Epidermoid cyst shows restriction on DWI due to keratin, simple cyst does not.
Distinguishing Feature
Seminoma appears as solid hypoechoic mass with marked hypervascularity. Simple cyst appears as anechoic cystic lesion and is completely avascular. No posterior acoustic enhancement in seminoma.
Distinguishing Feature
Teratoma shows cystic + solid + calcification triad. Simple cyst is purely cystic without solid component or calcification. Teratoma shows fat and calcification on MRI.
Distinguishing Feature
Abscess shows thick, irregular wall and internal echoes/debris with peripheral vascularity. Simple cyst is thin, smooth-walled and anechoic. Abscess is clinically accompanied by fever and pain.
Urgency
noneManagement
No treatment needed. Ultrasonographic follow-up at 6-12 months to confirm stability is reasonable. Aspiration or surgery NOT indicated for simple cyst. If cyst does not meet all simple cyst criteria, further evaluation with MRI recommended.Biopsy
Not NeededFollow-up
Single follow-up US at 6-12 months to confirm stability. If stable, no further imaging needed. Annual US only if patient anxious. Size increase, internal echoes, or wall thickening warrants MRI evaluation.Simple testicular cyst is a benign lesion of no clinical significance. No treatment is needed and ultrasonographic follow-up is sufficient. Surgery or aspiration is not indicated. Diagnostic reliability depends on meeting all four criteria together: completely anechoic, thin-walled, posterior enhancement, and avascular. If any of these criteria are not met (internal echoes, thick wall, septa, vascularity), simple cyst diagnosis cannot be made and further evaluation (MRI) is needed.
Simple testicular cyst is clinically insignificant and requires no treatment. US findings (anechoic, thin wall, posterior acoustic enhancement, avascular) allow definitive diagnosis. Follow-up is not necessary. Complicated cysts (internal echoes, thick wall, septation) may require additional evaluation. In older men, it may be confused with cystic ectasia of rete testis (tubular ectasia of rete testis) — which is also benign but shows a different appearance with multiple tubular anechoic structures.