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III./3.6.: Differential diagnosis
III./3.6.1.: Spermatocele
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Develops in the epidymis. It is visible as a well circumsribed, also cystic structure (anechoic on US image).
III./3.6.2.: Varicocele
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It might be idiopathic, if the venous valves or the venous walls are congenitally insufficient. Left sided dominancy has an anatomic reason. In a secondary form, abdominal mass (extraperitoneal tumor) obstructing the venous drainage or retroperitoneal lymphoma aggravating the lymphatic drainage should be suspected. Underlying reason of the drainage blockage must be searched. US images the substantial dilatation of the pampiniform venous plexus (over 2 mm), which are anechoic tubular structures adjacent to the testis, in which slow flow is detectable by color Doppler technique. US examination must be performed both in supine and standing positions and also with Valsalva maneuvre since the veins will be filled. Minimal invasive solution is served by the interventional radiology: testicular phlebography with embolisation can be carried out.
III./3.6.3.: Idiopathic form of scrotal edema
Occurs in infancy, incidental to mild pain, skin of the scrotum is swollen, edematous and has an inflammatory surface. US: testes are located in the scrotum, neither the testis nor the epididymides show any discrepancy in morphology/echogeneicity. Doppler examination indicates hyperperfusion.
III./3.6.4.: Testicular torsion
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The onset can be rapid, severe, possibly abdominal pain can be accompanied without fever. The torsion can be total or partial, developing outside the tunica vaginalis (extravaginal) or inside (intravaginal). The former form befalls rather in infancy, the latter form befalls rather in adolescence. The direction of the torsion is usually characteristic for the sidedness of the testis: whilst the direction is clockwise in the right testis, it is counterclockwise in the left testis. US: the image is dependent on the duration of the torsion. Enlarged testis can be observed, whose structure is hypoechogenic, and mixed, hyperechogenic and hypoechogenic areas might vary. Reactive hydrocele can develop around the testis often.
In early cases, Doppler examination is of a great help: no vascularisation can be seen centrally, neither arterial nor venous flow is detectable. If signs of arterial but no venous flow can be observed centrally, the torsion is partial. Central hyperperfusion indicates a spontaneous detorquation or an intermittantly appearing torquation. Testicular torsion must be distinguished from epididymitis: perfusion is increased in epididymitis in contrast to the torsion. MRI: enlargement of the testis can be observed, there is no contrast enhancement both in testis and in epididymis. Furthermore, hemorrhagic transformation can develop in both of them, with signal changes characteristic to the bleeding.
III./3.6.5.: Hydatid torsion
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A Morgagni-type tiny cyst, an embryonic remnant, which is called hydatid, is located on the superior pole of the testes. Torquation can also develop and its symptoms are very similar to ones of testicular torsion. Hydatid torsion occures in early adolescence, it is less painful compared to the testicular torsion and no abdominal symptoms are accompanied. During inspection, hemorrhage can be observed under the scrotal skin: „blue dot sign”. US has a diagnostic value: small hyperechoic lesion can be seen between the superior pole of the intact testis of normal echogeneicity and the intact epididymis. Doppler imaging indicates a hypoperfusion.
III./3.6.6.: Orchitis
Unilateral or bilateral. The most frequent inflammation of viral origin which might accompany the mumps disease of young adult males, however, separate occurance can is also possible without the swelling of salivary glands. It can be caused by other viruses as well, and bacterial origin is also possible. Painful testicular swelling with fever can also develop in gonorrhoea and extrapulmonary tuberculosis infection. US: testicular enlargement can be observed, which can be hypo- or hyperechogenic. This finding is reasonably aspecific (tumor, metastasis, infarction and torsion might show similar image). The víral form does form an abscess. Especially the differentiation from the torsion might be difficult using B-mode examination. Doppler examination can help, which images the increased vascularization characterised for inflammation.
III./3.6.7.: Epididymitis
It is the disease of adolescence, but occurence in adults is also possible following gonorrheal urethritis, cystitis, urological intervention (e.g. bladder catheterisation, cystoscopy), and through prostate hypertrophy and urine retention because of other cases. The disorder accompanies with fever, swelling, and also into the lower abdominal quandrants emanating pain. US: the epididymis, which follows the testis in longitudinal aspect, is thickened, its echogeneicity is inhomogeneous. The internal hypoechogeneous areas indicate abscedation. If the inflammatory process involves also the testis, similar echogenic pattern develops there as well because of the inflammation. Color Doppler technique images increased perfusion (in contrast to the testicular torsion).
III./3.6.8.: Scrotal trauma
The obscure trauma to the scrotal area might fracture the testis, the epididymis and other scrotal contents. Regarding the testis, this trauma can be laceration, hemorrhage, contusion. US image of testicular contusion: inhomogeneous echotexture, the contour can be irregular, furthermore, the burst line can be also visible. Trauma can cause also torsion, whose sign are (also) visible (e.g. decreased flow). The image of the bleeding is dependent on its age (with MRI as well), often only the Color Doppler examination can help in the differentiation from the tumor (since there is no Doppler sign in the hematoma, whileas the flow is increased in the tumor).
III./3.6.9.: Scrotal hernia
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As US is the primary investigation method of the scrotum/testis, content of the hernia is demonstrated also primarily by this method. If the hernia contains bowel loops, those are well visible by US. Sometimes passage examination (gastrointestinal application of positive contrast agent + X-ray) detects the cause of the enlarged scrotum and the content of the hernia.
III./3.6.10.: Testicular tumors
It is the disease of the youth, in which age group testicular tumor is one of the most frequent malignant tumor type. In testis, the most common ones are the seminomatous and non seminomatous (such as e.g. embryonal carcinoma, choriocarcinoma, teratoma, etc.) germinal cell tumors; the latter ones are characteristically so-called collisious (indicating that it consists of the mixture of multiple tumor types) tumors. Primary testicular lymphomas develop in latter age, but metastases can also eventuate. Testicular tumors are not painful, rather „heavy” feeling is present.
US: US-image of seminomas is homogeneously hypoechogenic, whileas non seminomas are rather inhomogeneously hyperechogenic. MRI: invasively growing seminoma usually involves the entire testis. T1-weighting shows almost identical signal intensity as the normal testicular tissue, but the tumor is a bit more hypointensive on T2, contrast enhancement is only poor. Non seminomas grow rather nodularly-expansively, the entire testis is not involved. The tumor is hypointense on both T1 and T2 weighted images, and poor contrast enhancement is observed. Lymphomas infiltrate the testis and epididymis equally.
III./3.6.11.: Cryptorchismus
Non scrotal topographic disorder of the testis. The late descent of the testis or the surgically corrected descended testicular cryptorchismus – due to the increased frequency of primary testicular tumors – can play a subsequent role in the ethiology of scrotal swelling. It can be unilateral or bilateral. The investigational possibilities are highlighted here, among which US has the primary role. US is effective if the testis (in 3/4 of the cases) is located in the inguinal canal, under the superior ingiunal ring. MRI examination, which has a good tissue contrast and provides multiplanar images, can demonstrate the intraabdominally sticked testes with high confidence (high signal on T2-weighted images, especially fat suppression technique can visualize them unequivocally).
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