Scrotal Mass and Scrotal Pain



Scrotal Mass and Scrotal Pain


Duane Meixner



Objectives



• Describe the sonographic appearance of the normal scrotal contents.


• Identify the clinical signs and symptoms of benign processes in the scrotum.


• Describe the sonographic appearance of benign findings in the scrotum.


• Identify the clinical signs and symptoms of clinically significant processes in the scrotum.


• Describe the sonographic appearance of common clinically significant pathologies of the scrotum.



CLINICAL SCENARIO


A previously healthy, 29-year-old man reports 12 days of fatigue and malaise with occasional nausea. On physical examination, a small tender palpable nodule is discovered on the lower pole of the right testis. Sonographic evaluation demonstrates a small cystic mass in the area of the palpable abnormality and a mostly solid complex mass occupying most of the right testicle (Fig. 28-1; see Color Plate 37). Discuss possible causes for the sonographic findings.


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FIGURE 28-1 (A), Small tunical cyst (calipers) represents the palpable abnormality. A mostly hypoechoic mass (arrows) occupies most of the testis. (B), Transverse view shows cystic components and internal blood flow (see Color Plate 37).


Sonography can display the scrotal contents in exquisite detail and is the imaging method of choice for evaluating the scrotum. When a patient presents with scrotal pain, or a scrotal mass is discovered or suspected clinically, a sonogram should be the first imaging test ordered. Not only are abnormalities within the testicle easily seen with ultrasound imaging, but also other conditions of the scrotum can be characterized, such as epididymal masses, fluid collections, and infectious processes. Along with clinical and laboratory findings, sonography can provide valuable information for the diagnosis and treatment planning of abnormalities in the scrotum.



Scrotum


The scrotum is an outpouching of the lower abdominal wall, with layers derived from the muscles and connective tissues. The structures contained within the scrotum are the testicles, the epididymides, and the proximal spermatic cords (Fig. 28-2). The testicles are two ovoid spermatogenic endocrine glands separated from each other within the scrotum by the scrotal septum. Each testicle has a capsule of fibrous connective tissue called the tunica albuginea. At the posterior aspect of the testicle, the tissue of the tunica albuginea enters the testicle to form the mediastinum testis and then extends toward the outer capsule as numerous septa, which create lobules that house the spermatogenic seminiferous tubules. The seminiferous tubules converge at the mediastinum to form the rete testis, a network of microtubules, which gives off several efferent ductules. The epididymal head comprises the convoluted efferent ductules that transport spermatozoa out of the testis into the epididymis. The ductules of the head converge to become a single coiled duct, the epididymal body and tail, passing next to the testis from the upper pole toward the lower pole. Near or at the inferior pole of the testis, the duct turns back toward the upper pole, deconvolutes, and enlarges slightly to become the ductus deferens, which exits the scrotum as part of the spermatic cord. Each scrotal compartment, or hemiscrotum, is lined by tunica vaginalis, a serous membrane that also covers the testicle and epididymis and encloses the potential peritesticular space.


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FIGURE 28-2 Anatomy of testis and epididymis.


Sonographic Findings


Normal testicles are homogeneous and mildly echogenic except for the mediastinum testis, which is hyperechoic, is of variable thickness, and runs along the posterolateral side of the testicle in a craniocaudal orientation (Fig. 28-3, A). Each testicle is approximately 5 cm × 3 cm × 2 cm in size. The peritesticular spaces normally contain small amounts of serous fluid. The normal epididymis may have a perceptible tubular appearance and has an echogenicity that is less than the testicle, although the head may be more echogenic than the rest of the epididymis (Fig. 28-3, B).


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FIGURE 28-3 (A), Transverse view of the testis shows the echogenic mediastinum (arrow) with septa radiating toward the capsule. (B), Dual, longitudinal image of normal scrotal contents. The epididymal head (white arrow), body (black arrow), and tail (open black arrow) lie adjacent to the homogeneous testis.


Extratesticular Mass


Many abnormalities that occur in the scrotum do not involve the testes. Any scrotal abnormality discovered by the patient or his physician may precipitate sonographic evaluation. Extratesticular masses are nearly always benign.



Cysts and Fluid


Epididymal Cysts and Spermatoceles


Epididymal cysts are serous fluid–filled cysts that occur anywhere in the epididymis. Spermatoceles are cystic dilations of the epididymal ductules containing spermatozoa and other debris and usually occur in the head. Both lesions are common. If large enough to be palpable, cysts and spermatoceles are discernible as a nodule separate from the testis, although larger lesions may manifest as generalized painless scrotal enlargement.



Sonographic Findings

Epididymal cysts and spermatoceles are indistinguishable sonographically. Both may appear as anechoic simple cysts (Fig. 28-4) or may contain fine low-level echoes, sometimes with precipitative layering. Scrotal cysts can be several centimeters in diameter and can be mistaken for a large hydrocele. Neither epididymal cyst nor spermatocele is of clinical significance unless large enough to be symptomatic. Spermatoceles tend to be solitary, whereas epididymal cysts are often multiple.


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FIGURE 28-4 (A), Palpable upper pole abnormality is an epididymal cyst or spermatocele. (B), Large epididymal cyst displaces testis inferiorly. (B, Courtesy Cindy Rapp, Radiology Imaging Associates, Greenwood Village, Colorado.)


Hydrocele


A hydrocele is an abnormal amount of serous fluid in the peritesticular space. Hydroceles may be unilateral or bilateral and can occur at any age. Congenital hydroceles are common in newborn boys because the processus vaginalis, the passage between the abdomen and scrotum, may not obliterate for some time after delivery. Acquired hydroceles can occur at any age and have many causes, including trauma, infection, infarction, torsion, and testicular neoplasms. The patient usually has unilateral painless scrotal enlargement, from minimal to large enough to alter gait. Most hydroceles transilluminate on clinical examination.



Sonographic Findings

A hydrocele appears as a fluid collection next to or around the testis, sometimes with septations. It might be seen as a relatively small amount of free paratesticular fluid, or it might be massive, enlarging the hemiscrotum greatly and compressing the testis against the inner scrotal wall. Large hydroceles are better demonstrated with dual imaging or an extended field of view (Fig. 28-5). In chronic hydroceles, echoes may be seen within the fluid; documenting acoustic streaming within such a hydrocele confirms the diagnosis. A very large hydrocele can be confused with a massive extratesticular cyst.


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FIGURE 28-5 (A), Extended field of view image of a massive hydrocele (calipers). The testis (arrow) is compressed at its attachment to the inner scrotal wall. It is unusually hyperechoic because of acoustic enhancement. (B), Moderate to large hydrocele with internal echoes.


Varicocele


A varicocele is a network of veins, the pampiniform plexus, dilated owing to increased venous pressure. It may be palpated as a sometimes painful cluster of tubular structures next to or superior to the testis. Varicoceles are predominantly found on the left because the left testicular vein is longer and enters the left renal vein at a right angle creating greater resistance to flow. Most varicoceles are extratesticular, but they can also extend into the testicular parenchyma. Varicoceles can be primary, caused by incompetent valves in the internal spermatic veins, or secondary, caused by compression of the testicular vein by an extrinsic process such as a retroperitoneal mass. Primary varicocele can occur at any age and is a correctable cause of male infertility.



Sonographic Findings

Varicoceles appear as dilated fluid-filled tubular structures in the posterolateral aspect of the scrotum measuring greater than 2 mm.1 Echogenic blood may be seen moving slowly through the veins, but color Doppler is essential in the diagnosis of a varicocele (Fig. 28-6; see Color Plate 38). Increased flow is identified within the prominent veins when the patient performs the Valsalva maneuver and is scanned while the patient is standing. Measuring the vein diameter should be done during the Valsalva maneuver also. If a large or unilateral right-sided varicocele is discovered, the right upper and lower quadrants should be investigated for external compression of the right testicular vein.


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FIGURE 28-6 (A), Gray-scale image of the spermatic cord shows a vein of the pampiniform plexus dilated to 4.1 mm. (B), Longitudinal color Doppler image shows minimal blood flow with normal respiration (see Color Plate 38). (C), Increased flow with Valsalva maneuver (see Color Plate 38).



Pyocele


A pyocele is a collection of peritesticular pus in patients with an inflammatory scrotal condition or who have sustained scrotal trauma. A patient with pyocele presents with an enlarged scrotum of varying degrees and may exhibit pain, redness, and localized warmth. If the patient has an active infection, he is likely to have an elevated white blood cell count and low-grade fever.



Sonographic Findings

A pyocele appears as a complex, sometimes septate fluid collection surrounding the testis (Fig. 28-7; see Color Plate 39). Unusual presentations include relatively homogeneous and echogenic material around the testis or a discrete mass near the testis. Gentle transducer pressure sometimes creates visible movement of the pyocele echoes. Similar to other peritesticular fluid collections, they can be of any size but rarely achieve several centimeters in greatest dimension.


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FIGURE 28-7 Complex septate paratesticular collection in a man 13 days after vasectomy, which was a pyocele at surgical exploration (see Color Plate 39).


Solid Lesions


Scrotal Pearls


Scrotal pearls are calcifications within the peritesticular space. They are thought to be caused by epididymitis, testicular torsion, torsion of the appendix testis or appendix epididymis, inflammation, or a chronic hydrocele. They are usually silent but can sometimes be palpated.






Scrotal Hernia


Scrotal hernias are inguinal hernias that enter the scrotum. These may contain serous fluid contained by peritoneum, small bowel, colon, mesentery, or omentum. The abdominal contents are able to enter the scrotum because the processus vaginalis persists after birth or recanalizes later. There are two types of hernias—indirect and direct. Indirect hernias are more common than direct hernias, but in either case the patient has a swollen scrotum of variable size that contains a palpable mass. Incarceration occurs when the abdominal structures are no longer able to pass between the abdomen and scrotum, potentially causing the blood supply of the herniated tissue to be compromised. An incarcerated hernia is likely to be painful, and if timely surgery is not performed, the incarcerated tissue becomes ischemic, then infarcted, and finally necrotic and gangrenous.



Sonographic Findings

Sonography reveals a mass of greatly variable echogenicity and echotexture depending on what structures are herniated to the scrotum (Fig. 28-10). There may be variably echogenic fluid with or without a visible hernia sac or a solid mass of varying complexity. Shadowing from air may be identified. If peristaltic motion is identified, the diagnosis of scrotal hernia is confirmed. Gentle transducer pressure may demonstrate reduction of a hernia in the proximal scrotal space, and a Valsalva maneuver may force a hernia deeper into the hemiscrotum; both can aid in the diagnosis. Sonography is not dependable for differentiating indirect from direct hernias.


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FIGURE 28-10 (A), Deep to the testis (seen at the top of the image) lie herniated loops of bowel, some fluid-filled. Active peristalsis was noted in real time. (B), Dual image of a large mesenteric hernia (arrows) superior to the testis. On Valsalva, the mass protruded farther into the scrotum.


Cystic Testicular Mass


Every solid intratesticular mass must be considered malignant until proven otherwise. Scrotal sonography approaches 100% accuracy in distinguishing a solid mass from a cystic mass, but it is poor for distinguishing whether a solid intratesticular mass is malignant or benign.






Epidermoid Cyst


Epidermoid cysts account for only about 1% of testicular neoplasms. They are benign keratin-containing cysts with an “onion-skin” lamellar architecture. They most commonly are discovered as a well-circumscribed, painless testicular mass in postpubertal boys and men 40 years old or younger.1



Sonographic Findings


Epidermoid cysts manifest as well-defined hypoechoic round or oval masses, and although they are cysts, acoustic enhancement is absent (Fig. 28-12). The concentric laminar architecture within these lesions sometimes generates a whorled appearance that is suggestive of the diagnosis. Also suggestive is the absence of internal vascularity on Doppler examination. If these characteristics are seen in a testicular mass, it must be reported so that surgical planning can allow for the possibility of a testis-sparing enucleation.


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FIGURE 28-12 Epidermoid cyst demonstrating whorled “onion-skin” lamellar appearance.

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Aug 27, 2016 | Posted by in ULTRASONOGRAPHY | Comments Off on Scrotal Mass and Scrotal Pain

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