Sonography of the Scrotum: Case-Based Review

AJR Integrative Imaging LIFELONG LEARNING FOR RADIOLOGY Sonography of the Scrotum: Case-Based Review Joseph W. Stengel 1,2 and Erick M. Remer 1 ABSTRACT Objective We discuss five scenarios in which sonography is useful for diagnosing scrotal abnormalities, including painful scrotal disorders, an incidental disorder, and scrotal masses. Practice questions are included for your review. Sonography is the primary diagnostic tool for diagnosing disorders in the scrotum. INTRODUCTION Sonography is the primary imaging modality used to diagnose disorders of the scrotum and its contents. It is advocated as the most appropriate study in the setting of acute scrotal pain in patients without trauma [1]. Neoplastic, in flam matory, congenital, and vascular abnormalities are detected with high sensitivity and sonographic findings are key to guiding clinical management. EDUCATIONAL OBJECTIVES By completing this educational activity, the participant will: A. Exercise, self-assess, and improve his or her understanding of the sonographic features of diseases of the scrotum. B. Exercise, self-assess, and improve his or her understanding of the clinical features of diseases of the scrotum. Scenario 1 A 17-year-old boy presents with acute onset of left scrotal pain approximately 10 hours earlier. On physical examination, the left scrotum is diffusely tender and mildly ery thematous. Gray-scale sonography shows markedly heterogeneous echotexture of the left testis (Fig. 1A). By comparison, the echogenicity of the right testis is normal (Fig. 1B). Color Doppler sonography shows no intratesticular flow and minimal flow surrounding the left testis (Fig. 2). QUESTION 1 What is your preferred diagnosis? A. Acute epididymoorchitis. B. Acute testicular torsion. C. Segmental testicular infarction. D. Infiltrating mass. QUESTION 2 Which sonographic feature is most specific for acute testicular torsion? A. Heterogeneous echotexture. B. Absence of flow. C. Diffuse enlargement of the affected testis. D. Hydrocele. QUESTION 3 Which of the following is TRUE regarding segmental testicular infarction? A. It usually involves the inferior portion of the testis. B. It can be easily distinguished from testicular tumor on color Doppler sonography. C. Embolic disease is the proposed mechanism. D. It has been linked to sickle cell disease and hypersensitivity angiitis. Solution to Practice Question 1 Acute epididymitis is usually the result of descending infection often caused by urinary tract pathogens. In young men, it most commonly results from gonococcus or Chlamydia organisms. If epididymitis involves the testis (epididymoorchitis), sonography will frequently show an Keywords: infection, neoplasm, sonography, testicle, torsion DOI:10.2214/AJR.07.7000 Received March 15, 2007; accepted after revision May 25, 2007. 1 Section of Abdominal Imaging, Imaging Institute, Cleveland Clinic, 9500 Euclid Ave. A21, Cleveland, OH 44195. Address correspondence to E. M. Remer (remere1@ccf.org). 2 Present address: Department of Radiology, University of California San Francisco, San Francisco, CA 94143. AJR 2008;190:S35 S41 0361 803X/08/1906 S35 American Roentgen Ray Society S35

Stengel and Remer Fig. 1 17-year-old boy with acute scrotal pain. A, Gray-scale transverse sonogram scrotum shows markedly heterogeneous echotexture of left testis. B, Sagittal color Doppler sonogram of left testis shows markedly heterogeneous echotexture and lack of flow within the testis. Fig. 2 51-year-old man with acute left scrotal pain after bowel surgery. Color Doppler sonogram shows focal rounded hypoechoic avascular lesion in superior pole of left testis. Segmental infarction is diagnosis at orchiectomy. enlarged, heterogeneous, predominantly hypoechoic testis with increased color flow. Option A is not the best response. The absence of flow in the affected testis shown on color and spectral Doppler sonography is a highly sensitive and specific finding in acute testicular torsion. Option B is the best response. Although patients with segmental testicular infarction usually present with an acute scrotum, sonography typically shows a wedge-shaped, hypoechoic region of absent flow with otherwise normal testicular parenchyma. Option C is not the best response. Although tumors can be difficult to distinguish from benign entities, testicular tumors are an uncommon cause of acute scrotal pain. Most A large and infiltrative tumors are hypervascular. Option D is not the best response. Solution to Practice Question 2 In torsion, the testis becomes enlarged and heterogeneous within the first 6 hours. Heterogeneous echotexture, however, is a common finding in sonograms for evaluation of acute scrotal pain regardless of cause. Option A is not the best response. Testicular enlargement (option C) and hydrocele (option D) are frequent, but nonspecific, findings in patients with testicular torsion. Unilateral absent flow is the most accurate sign of acute testicular torsion. Keep in mind, however, that intermittent or incomplete torsion may result in false-negative studies. Option B is the best response. Solution to Practice Question 3 Segmental testicular infarction is an ischemic process observed on sonography as a focal, rounded, or wedge-shaped avascular area, most often in the upper or middle portion of the testis (Fig. 2). Option A is not the best response. Differentiation from a small, hypovascular, intratesticular tumor on sonography is difficult, and in many cases the diagnosis is made after orchiectomy. Option B is not the best response. MRI may prove helpful to make a more specific preoperative diagnosis [2]. Although no clear cause has been determined, the proposed mechanism is torsion and detorsion of the testis producing ischemia in the upper pole of the testis, a region with an inconstant collateral arterial supply. Option C is not the best response. The list of conditions associated with segmental testicular infarction is long and includes acute epididymoorchitis, polycythemia, sickle cell disease, hypersensitivity angiitis, Wegener s granulomatosis, and pelvic surgery, especially herniorrhaphy. Option D is the best response [3]. B S36

Sonography of the Scrotum: Review The diagnosis in this patient is acute testicular torsion. Color Doppler sonography is instrumental in differentiating torsion from other causes of acute scrotal pain. Unilateral absent or diminished flow is the most accurate sign of torsion. Although some peripheral blood flow can be seen in the torsed testis, the presence of central flow is a strong negative predictor. The gray-scale sonographic appearance of torsion varies with time. The testis becomes enlarged and inhomogeneous within the first 6 hours, and heterogeneity worsens in the subacute phase (6 hours 5 days). Worsening degree of heterogeneity appears Scenario 2 A 61-year-old man presents with scrotal swelling and pain of 2 days duration. Onset of the pain followed heavy lifting. Gray-scale sonography and Doppler sonography of the scrotum are performed. Gray-scale sonography shows marked epididymal enlargement (Fig. 3A), hypoechogenicity, and hydrocele (Fig. 3B). Color Doppler sonography shows increased color flow (hyperemia) in the epididymis and testis (Fig. 3C). QUESTION 4 Which sonographic feature is most sensitive for scrotal inflammation? A. Scrotal skin thickening. B. Hydrocele. C. Hyperechoic epididymal echotexture. D. Scrotal or epididymal hyperemia. E. Enlargement of the epididymis or scrotum. QUESTION 5 In the United States, what is the most common causative organism in acute epididymoorchitis in men older than 50 years? A. Mycobacterium tuberculosis. B. Escherichia coli. C. Neisseria gonorrhoeae. D. Chlamydia organisms. E. Klebsiella organisms. to correspond to loss of viability [4]. Hydrocele and scrotal skin thickening are usually present but are nonspecific. The degree of torsion can be variable, ranging from 180 to 720. Lesser degrees of torsion may produce incomplete occlusion of blood flow and lead to chronic ischemia. Torsion of the testicular appendages (appendix testis or appendix epididymis) occurs predominantly in boys 7 14 years old and can mimic testicular torsion clinically. The torsed appendix is seen on sonography as a round extratesticular mass with high or mixed echogenicity and no Doppler flow. Blood flow in the testes, however, is normal, although paratesticular hyperemia may be seen. Solution to Practice Question 4 The hallmark of scrotal inflammation is hyperemia of the epididymis, testis, or both on color Doppler sonography. The sensitivity of color Doppler sonography for scrotal inflammation is close to 100%. Furthermore, in 20% of patients with epididymitis and 40% of patients with orchitis, gray-scale sonography is normal and hyperemia may be the only finding [5]. Option D is the best response. Scrotal skin thickening, reactive hydrocele, and increased epididymal echotexture are frequent, but nonspecific, findings in patients with acute scrotal pain. Options A, B, and C are not the best responses. Epididymal enlargement can be seen in torsion, trauma, epididymitis, and infiltrative processes such as leukemia and lymphoma. Option E is not the best response. Solution to Practice Question 5 Approximately 2 4% of tuberculous infections involve the genitals; however, epididymal tuberculosis is uncommon in the United States [6]. Option A is not the best response. Infectious epididymoorchitis is usually the result of descending infection caused by urinary tract pathogens, most commonly Escherichia coli. Option B is the best response. In young adults, scrotal infection usually results from sexually transmitted diseases. Options C and D are not the best responses. Pseudomonas organisms, Proteus mirabilis, and Klebsiella organisms are less common urinary tract pathogens and less common causes of epididymitis. Option E is not the best response. The diagnosis in this patient is acute epididymo-orchitis. Infectious epididymitis commonly involves the epididymal head but may involve the entire epididymis in up to 50% of cases. Involvement of the adjacent testis occurs in 20 40% of cases and can be focal or diffuse. Although hyperemia allows differentiation from complete torsion, trauma can cause enlargement and hyperemia in the absence of infection. Granulomatous diseases such as tuberculosis, brucellosis, and sarcoidosis are less common causes of epididymitis and orchitis. Orchitis without epididymitis is typical of infection by the paramyxovirus causing mumps. Mumps orchitis may be bilateral S37

Stengel and Remer in up to 35% of cases. Lymphoma involving the testis can be difficult to distinguish from epididymoorchitis on the basis of sonographic features alone. Like epididymoorchitis, lymphoma Scenario 3 A 37-year-old man presents with scrotal pain after testicular trauma. Multiple punctate, nonshadowing, echogenic foci are noted on sonography of the right testis (Fig. 4). No intratesticular mass is seen. Solution to Practice Question 6 The typical distribution of this entity is diffuse and bilateral. Option A is not the best response. Several reports have shown concomitant intratubular germ cell neoplasia and microcalcifications in the same testis [7]. However, the calcifica- A C Fig. 3 61-year-old man with scrotal swelling and pain for 2 days. A and B, Sagittal (A) and transverse (B) gray-scale sonograms of epididymis show marked epididymal enlargement (A) as well as hypoechogenicity and hydrocele (B). Epididymal enlargement, hypoechogenicity, and hydrocele are seen in both A and B. C, Color Doppler sonogram shows increased color flow (hyperemia) in epididymis and testis. causes hypoechoic enlargement of the testis and epididymis with hyperemia; however, lymphoma is typically painless and will not resolve with interval antibiotic treatment. QUESTION 6 In the entity demonstrated in Scenario 3, the punctate, echogenic foci in the testes are: A. Usually unilateral. B. Intratubular germ cell neoplasia. C. Often painful. D. The result of trauma. E. Laminated calcium deposits in the seminiferous tubules. B S38

Sonography of the Scrotum: Review QUESTION 7 Which of the following is NOT a current management recommendation for patients with testicular microlithiasis? A. Physical examination at least annually. B. Annual sonographic examinations. C. Consideration of biopsy to detect intratubular germ cell neoplasia. D. Screening CT of the chest, abdomen, and pelvis. E. Prophylactic orchiectomy. tions themselves are not germ cell neoplasia. Although there is direct evidence of an increased risk of concurrent malignancy in the setting of intratubular germ cell neoplasia, the subsequent development of germ cell neoplasm in patients with isolated testicular microlithiasis is less well established [8]. Option B is not the best response. Microlithiasis is often discovered incidentally on sonography obtained for scrotal pain or trauma; however, the condition is neither painful nor associated with trauma. Options C and D are not the best responses. Histologically, the punctate bright echoes in testicular microlithiasis are laminated calcium deposits in the lumen of the seminiferous tubules [9]. Option A is the best response. Scenario 4 A 28-year-old man presents with a nontender, palpable right testicular mass. Gray-scale sonography shows a well-circumscribed mass in the testis with hyperechogenic rim and heterogeneous, predominantly sonolucent center (Fig. 5). Some acoustic shadowing is observed. No laminations are identified. Solution to Practice Question 8 Seminoma is the most common type of testicular tumor. They are usually well-circumscribed, hypoechoic lesions containing low-level echoes, but not calcifications. Option A Fig. 4 37-year-old man with scrotal pain after trauma. Transverse gray-scale sonogram of right testis shows multiple punctate, nonshadowing, echogenic foci but no intratesticular mass. Solution to Practice Question 7 A lack of consensus exists regarding the preferred followup of microlithiasis in patients without a concurrent neoplasm, and thus many differing recommendations can be found in the literature and in practice [10]. Most authors agree that at least an annual physical examination and scrotal sonography are prudent. Options A and B are not the best responses. Others have gone further, advocating testicular biopsy to detect concurrent premalignant intratubular germ cell neoplasia. Option C is not the best response. Because the relative risk of concurrent neoplasm in a patient with testicular microlithiasis has been reported to be as high as 21.6-fold [11], some experts recommend screening CT of the chest, abdomen, and pelvis when microlithiasis is detected. Option D is not the best response. The latter two recommendations remain controversial. Unlike prophylactic mastectomy in highrisk women, prophylactic orchiectomy has not been advocated in the literature. Option E is the best response. The diagnosis in this patient is testicular microlithiasis, which is defined as five or more punctuate echogenic foci in a single transducer field. A wide variation is seen in the reported prevalence of testicular microlithiasis, ranging from 0.68% to 18.1%. Although testicular microlithiasis is clearly associated with concurrent neoplasm, significant controversy exists about the risk that it leads to the subsequent development of neoplasm [8, 12]. No real differential exists for microcalcifications. Clustered intratesticular macrocalcifications (>3 mm) can be seen in so-called burned-out germ cell tumors or Sertoli cell tumors and may be seen after trauma. QUESTION 8 Sonography of a nontender, palpable testicular mass in a young adult man shows a wellcircumscribed mass in the testis with alternating hyperechoic and hypoechoic rings. Which of the following is the most likely diagnosis? A. Seminoma. B. Lymphoma. C. Epidermoid cyst. D. Adenomatoid tumor. E. Lipoma. S39

Stengel and Remer is not the best response. Lymphoma typically presents as either focal or more diffuse hypoechoic regions with increased Doppler flow and occasional involvement of the adjacent epididymis. Option B is not the best response. Alternating bands of increased and decreased echogenicity, the so-called onion-ring appearance, is characteristic of an epidermoid cyst; however, the sonographic appearance is variable [13]. Epidermoid cysts with a target appearance, a sharply defined mass with a rim of calcium, and a solid mass with an echogenic rim, as in this patient, have been described [14]. Option C is the best response. Adenomatoid tumors are mixed-echogenicity tumors of the epididymis. Option D is not the best response. Lipomas typically arise in the spermatic cord. Option E is not the best response. Fig. 5 28-year-old man with nontender, palpable right testicular mass. Sagittal gray-scale sonogram shows well-circumscribed mass in testis with hyperechogenic rim and heterogeneous, predominantly sonolucent center. Some acoustic shadowing is seen. No laminations are identified. Scenario 5 A 37-year-old man presents with a painless, firm lump adjacent to the left testis. Gray-scale sonography shows a mixed-echogenicity mass adjacent to the left testis in the expected position of the epididymis (Fig. 6). QUESTION 9 Which of the following is TRUE regarding extratesticular scrotal masses? A. Cystic masses are usually malignant. B. Epididymal papillary cystadenomas are associated with von Hippel-Lindau syndrome. C. Most supernumerary testes are intraperitoneal. D. Adenomatoid tumors are the most common. QUESTION 10 Which of the following is the most common tumor involving the spermatic cord? A. Leiomyoma. B. Rhabdomyosarcoma. C. Primary lymphoma. D. Lipoma. E. Adenomatoid tumor. The diagnosis in this patient is intratesticular epidermoid cyst. Several embryologic origins of this lesion have been postulated, including squamous metaplasia of the rete testis, epidermal inclusion, or monodermal development of a teratoma [15]. The main internal component of the epidermoid cyst is keratin. The variable sonographic appearance probably reflects the evolution of the lesion, with successive layers of keratin and desquamated epithelium creating the laminated appearance. In masses without classic sonographic findings, epidermoid cysts may be mistaken for malignancy. Treatment has been controversial, but most sources now agree that excisional biopsy and biopsy of the adjacent parenchyma to rule out intratubular germ cell neoplasia can be undertaken in men with negative tumor markers and characteristic sonographic findings. Other benign testicular masses include tunica albuginea cysts, tubular ectasia of the rete testis, abscess, hematoma, adrenal rests, and segmental infarction. Solution to Practice Question 9 In contrast to testicular masses, most extratesticular scrotal masses are benign [16]. Cystic scrotal masses are especially likely to be benign. Option A is not the best response. Supernumerary testes are rare, usually presenting as a painless, scrotal mass. Twenty percent of supernumerary testes are inguinal. Option B is not the best response. Papillary cystadenoma, a benign tumor of the epididymis, has a strong association with von Hippel-Lindau (VHL) disease. Bilateral epididymal cystadenomas are virtually pathognomonic for VHL. Option B is the best response. Adenomatoid tumor is the most common epididymal tumor; however, lipomas, which usually occur in the spermatic cord, are the most common extratesticular scrotal tumor [16]. Option D is not the best response. Solution to Practice Question 10 Lipomas are the most common extratesticular scrotal tumor, arising most often in the spermatic cord. Option D is the best response. They account for approximately half of all QUESTION 11 Which of the following is TRUE regarding adenomatoid tumors of the scrotum? A. They are usually malignant. B. They usually involve the epididymal head. C. They may be intratesticular. D. They occur mostly in older men. S40

Sonography of the Scrotum: Review Fig. 6 37-year-old man with painless, firm lump adjacent to left testis. Grayscale sonogram shows mixed-echogenicity mass adjacent to left testis in expected position of epididymis. cord tumors. Other benign tumors of the cord include leiomyoma, lymphangioma, and dermoid, but these are much less common. Option A is not the best response. Rhabdomyosarcoma and liposarcoma are the most common sarcomas of the scrotum, usually arising from the mesoderm of the spermatic cord [16]. Rhabdomyosarcomas occur predominantly in children and often present with retroperitoneal adenopathy and distant metastasis. Option B is not the best response. Lymphoma involving the epididymis or spermatic cord without testicular involvement is extremely rare. Option C is not the best response. Adenomatoid tumors involve the epididymis. Option E is not the best response. Solution to Practice Question 11 Adenomatoid tumors of the epididymis account for approximately 30% of paratesticular neoplasms. They are invariably benign. Option A is not the best response. Although adenomatoid tumors can occur anywhere in the epididymis, they most often arise in the epididymal tail. Option B is not the best response. Intratesticular extension can be seen, in which case it can be indistinguishable from germ cell tumor. Option C is the best response. Most adenomatoid tumors are diagnosed in men between the ages of 20 and 50 years. Option D is not the best response. Adenomatoid tumors are benign neoplasms of mesothelial origin that account for nearly 30% of all paratesticular tumors; they are commonly found near the lower pole of the testis [17]. The sonographic appearance of adenomatoid tumor of the epididymis is extremely variable, although they are typically homogeneously hyperechoic. Tumors predomi- nantly arise in the epididymis, where they can be characterized as extratesticular. About 14% arise from the testicular tunica. Origin from the deep layer of the tunica vaginalis testis or the tunica albuginea may lead to intratesticular growth that may make differentiation from germ cell tumor impossible. MRI findings are useful in suggesting that the mass arises from the tunical surface of the testis rather than from the peripheral seminiferous tubules [18]. Other benign tumors of the epididymis include leiomyomas and papillary cystadenomas. Lipomas, hematomas, and hernias are common benign masses of the spermatic cord. References 1. Remer EM, Francis IR, Baumgarten DA, et al. Acute onset of scrotal pain without trauma, without antecedent mass. ACR Appropriateness Criteria 2007. www.arrs.org. Last accessed 4/11/2008 2. Kodama K, Yotsuyanagi S, Fuse H, Hirano S, Kitagawa K, Masuda S. Magnetic resonance imaging to diagnose segmental testicular infarction. 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